Comparison of Outcomes Following Anterior vs Posterior Fusion Surgery for Patients With Degenerative Cervical Myelopathy: An Analysis From Quality Outcomes Database

Comparison of Outcomes Following Anterior vs Posterior Fusion Surgery for Patients With... Abstract BACKGROUND The choice of anterior vs posterior approach for degenerative cervical myelopathy that spans multiple segments remains controversial. OBJECTIVE To compare the outcomes following the 2 approaches using multicenter prospectively collected data. METHODS Quality Outcomes Database (QOD) for patients undergoing surgery for 3 to 5 level degenerative cervical myelopathy was analyzed. The anterior group (anterior cervical discectomy [ACDF] or corpectomy [ACCF] with fusion) was compared with posterior cervical fusion. Outcomes included: patient reported outcomes (PROs): neck disability index (NDI), numeric rating scale (NRS) of neck pain and arm pain, EQ-5D, modified Japanese Orthopedic Association score for myelopathy (mJOA), and NASS satisfaction questionnaire; hospital length of stay (LOS), 90-d readmission, and return to work (RTW). Multivariable regression models were fitted for outcomes. RESULTS Of total 245 patients analyzed, 163 patients underwent anterior surgery (ACDF-116, ACCF-47) and 82 underwent posterior surgery. Patients undergoing an anterior approach had lower odds of having higher LOS (P < .001, odds ratio 0.16, 95% confidence interval 0.08-0.30). The 12-mo NDI, EQ-5D, NRS, mJOA, and satisfaction scores as well as 90-d readmission and RTW did not differ significantly between anterior and posterior groups. CONCLUSION Patients undergoing anterior approaches for 3 to 5 level degenerative cervical myelopathy had shorter hospital LOS compared to those undergoing posterior decompression and fusion. Also, patients in both groups exhibited similar long-term PROs, readmission, and RTW rates. Further investigations are needed to compare the differences in longer term reoperation rates and functional outcomes before the clinical superiority of one approach over the other can be established. Cervical myelopathy, Anterior discectomy and fusion, Posterior cervical fusion, Quality outcomes database, Neurosurgical registry ABBREVIATIONS ABBREVIATIONS ACCF anterior cervical corpectomy and fusion ACDF anterior cervical discectomy and fusion ASA American Society of Anesthesiologists BMI body mass index CAD coronary artery disease CI confidence interval CSM cervical spondylotic myelopathy EQ-5D EuroQol-5D HR hazard ratio LOS length of stay mJOA modified Japanese Orthopedic Association NDI Neck Disability Index NRS numeric rating scale OR odds ratio PROs patient-reported outcomes QOD Quality Outcomes Database RTW return to work US United States Degenerative cervical myelopathy is the most common cause of acquired neurological disability in people older than 50 yr of age.1 It may be attributed to an array of degenerative changes occurring in the aging spine, including degenerative disc disease, facet joint arthritis, ligamentum flavum hypertrophy, and ossification of the posterior longitudinal ligament.2 According to a report published in 2009, degenerative cervical myelopathy is the most common primary diagnosis (36%) among elderly patients admitted to a hospital between 1992 and 2005 in the United States (US) to undergo surgical treatment for degenerative cervical spine disease.3 Surgical management is the treatment of choice in cases of progressive or severe neurological deficits. However, the optimal approach, ie anterior vs posterior, still remains an area of contention among surgeons.4-7 Anterior decompressive approaches typically involve anterior cervical discectomy and fusion (ACDF) or anterior cervical corpectomy and fusion (ACCF), whereas posterior approaches comprise laminoplasty or laminectomy with or without arthrodesis. In general, an anterior approach is preferred in cases of ventral compression occupying few levels while attempting to restore cervical lordosis.4 Previous studies have reported up to 90% fusion rates and significant clinical improvement following ACDF for single-level cervical myelopathy;8,9 however, for the multisegments (≥3) cervical myelopathy the evidence on the relative efficacy of different treatment modalities is still unclear.10-12 To address this gap in current knowledge, we conducted an analysis of prospectively collected data from a multicenter spine registry to determine the outcomes following anterior and posterior approach for patients undergoing multilevel fusion for degenerative cervical myelopathy. METHODS We queried the Quality Outcomes Database (QOD) registry for patients undergoing 3 to 5 level cervical spine surgery for primary indication of degenerative cervical myelopathy. An approval for the study and waiver of informed consent was obtained from the institutional review board. The QOD is a prospective registry, enrolling patients since 2012, and is designed to evaluate risk-adjusted expected morbidity and 12-mo outcomes with the aim of improving efficiency and quality of care for the most commonly performed spinal surgical procedures.13,14 The cervical spine module was developed in 2013, enrolling patients undergoing surgery for degenerative cervical spine disease. Inclusion and Exclusion Criteria The general inclusion and exclusion criteria for the QOD spine modules are described previously.13-15 For this analysis, patients presenting with myelopathy and undergoing equal to or more than 3-levels surgery with at least 12 mo of follow-up were eligible for inclusion in the study. The clinical variables and outcomes were compared between those undergoing anterior or posterior approach. Anterior approaches consisted of ACDF with and without corpectomy, whereas posterior approaches consisted of posterior cervical decompression with instrumented fusion. Outcomes of Interest Baseline and postoperative patient-reported outcomes (PROs) including disability, pain, and quality of life are captured at baseline, 3-mo and 12-mo after surgery via self-administration or phone interview. For this study, the outcomes of interest were 12 mo Neck Disability Index (NDI),16 numeric rating scale (NRS) for neck and arm pain,17 EuroQol-5D (EQ-5D),18 modified Japanese Orthopedic Association scale (mJOA),10 and NASS satisfaction questionnaire.19 Other outcomes of interest included hospital length of stay (LOS), 90-d readmission, and return to work (RTW). The occurrence of postoperative complications, including deep venous thrombosis, pulmonary embolism, myocardial infarction, urinary tract infection, surgical site infection, hematoma, dysphagia, vocal cord paralysis, CSF leak, wound dehiscence, cerebrovascular accident within 30 d, and new motor deficit were also compared between the anterior and posterior approach. Statistical Analysis Descriptive statistics (mean, standard deviation, median, and interquartile range for continuous variables; frequency and proportion for categorical variables) were used for patient demographic and comorbidity information as well as baseline symptoms, diagnosis, PRO scores, LOS, readmission, RTW, and complications. Between the 2 surgical approach groups, continuous variables were compared using Wilcoxon Rank Sum test, whereas categorical variables were compared using Pearson's Chi-square. Responder/nonresponder analysis was also performed in order to investigate to compare the baseline profile of patients who completed the 12-mo follow-up evaluation vs those who did not. Multivariable proportional odds ordinal logistic regression models were fitted for NDI, NRS-neck pain, NRS-arm pain, EQ5D, mJOA satisfaction, and LOS; logistic regression model was fitted for readmission, and Cox proportional hazards model was fitted for RTW. The variables included in the models were age, gender, race, body mass index (BMI), American Society of Anesthesiologists (ASA) grades, insurance status, smoking, diabetes, coronary artery disease (CAD), depression, principal diagnosis, presence of motor deficit or numbness, ambulation, duration of symptoms, education level, worker's compensation, employment liability claim, principal symptom, and baseline functional outcome score. The confidence intervals (CI) for the adjusted odds ratio (OR) or hazard ratio (HR) of surgical procedure were computed using profile likelihood method. The analysis was performed using R 3.1.2 and rms package.20,21 RESULTS A total of 363 patients met the inclusion criteria for the study. Of those, 245 patients (anterior-163, posterior-82) had 12-mo follow-up (70.8% follow-up rate) and were further analyzed. In the anterior approach group, 116 patients underwent ACDF and 47 patients underwent corpectomy. On responder analysis, no significant differences were found between patients with and without complete 12-mo follow-up data, except for diabetes (17% vs 29%, P = .012) and number of surgical levels (overall P = .008; Table, Supplemental Digital Content). Patients undergoing anterior surgery were slightly younger (median age 61 vs 66 yr, P < .001); no differences were observed with regards to gender (male: 47% vs 52%, P = .62), BMI distribution (median: 31 vs 30, P = .43), smoking status (22% vs 21%, P = .81), CAD (11% vs 10%, P = .76), diabetes (17% vs 17%, P = .92), and ASA classification (overall P = .68; Table 1). Baseline symptoms, diagnoses, and PROs are presented in Table 2. Patients undergoing anterior surgery were more often diagnosed with intervertebral disc herniation (15% vs 4%) whereas those undergoing posterior surgery had more often central canal stenosis (77% vs 62%; overall P = .014). There was no significant difference in the baseline PROs between the anterior approach and posterior approach group, (median NDI [38 vs 37, P = .19], EQ-5D [0.69 vs 0.6, P = .77], median NRS-neck pain [6 vs 5, P = .16], median NRS-arm pain [5 vs 5, P = .24]), except for mJOA (13 vs 12, P = .02). In terms of number of level fused, patients undergoing anterior surgery were more likely to receive 3-level surgery (74% vs 35%), whereas patients undergoing posterior surgery were more likely to receive 4-level (49% vs 25%) or 5-level fusion (16% vs 2%; overall P < .001). Finally, an anterior approach was associated with relatively lower intraoperative blood loss (100 vs 200 ml, P < .001); operative time was not different between the 2 groups though (166 vs 146 min, P = .06). TABLE 1. Patient Demographics and Comorbidities by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Age, median (IQR) 245 61 (54-69) 66 (57-72) <.001 Male gender, n (%) 245 76 (47) 41 (52) .62 BMI, median (IQR) 245 31 (26-34) 30 (26-33) .43 Race, n (%) 245 .32  White 138 (85) 63 (77)  Other 25 (15) 19 (20) Education, n (%) 241 <.001  Less than high school 6 (4) 13 (16)  High school diploma 78 (49) 31 (38)  Two-year college degree 42 (26) 10 (12)  Four-year college degree 21 (13) 10 (12)  Postcollege 13 (8) 17 (21) Smoking, n (%) 242 36 (22) 17 (21) .81 CAD, n (%) 245 18 (11) 8 (10) .76 Diabetes, n (%) 245 27 (17) 14 (17) .92 Depression, n (%) 245 .031  Moderate 58 (36) 41 (50)  Extreme 25 (15) 5 (6) ASA, n (%) 245 .68  1/2 75 (46) 40 (49)  3/4 88 (54) 42 (51) Employment, n (%) 245 .12  Sedentary 12 (7) 11 (13)  Light 24 (15) 8 (10)  Medium 21 (13) 5 (6)  Heavy 14 (9) 4 (5)  Unemployed/attending school 92 (56) 54 (66) Worker's Compensation, n (%) 242 3 (2) 1 (1) .72 Liability, n (%) 242 9 (6) 2 (2) .26 Insurance, n (%) 245 .045  Uninsured 2 (1) 1 (1)  Medicare 64 (40) 40 (49)  Medicaid 3 (2) 3 (4)  VA/Government 4 (2) 7 (9)  Private 90 (55) 31 (38) Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Age, median (IQR) 245 61 (54-69) 66 (57-72) <.001 Male gender, n (%) 245 76 (47) 41 (52) .62 BMI, median (IQR) 245 31 (26-34) 30 (26-33) .43 Race, n (%) 245 .32  White 138 (85) 63 (77)  Other 25 (15) 19 (20) Education, n (%) 241 <.001  Less than high school 6 (4) 13 (16)  High school diploma 78 (49) 31 (38)  Two-year college degree 42 (26) 10 (12)  Four-year college degree 21 (13) 10 (12)  Postcollege 13 (8) 17 (21) Smoking, n (%) 242 36 (22) 17 (21) .81 CAD, n (%) 245 18 (11) 8 (10) .76 Diabetes, n (%) 245 27 (17) 14 (17) .92 Depression, n (%) 245 .031  Moderate 58 (36) 41 (50)  Extreme 25 (15) 5 (6) ASA, n (%) 245 .68  1/2 75 (46) 40 (49)  3/4 88 (54) 42 (51) Employment, n (%) 245 .12  Sedentary 12 (7) 11 (13)  Light 24 (15) 8 (10)  Medium 21 (13) 5 (6)  Heavy 14 (9) 4 (5)  Unemployed/attending school 92 (56) 54 (66) Worker's Compensation, n (%) 242 3 (2) 1 (1) .72 Liability, n (%) 242 9 (6) 2 (2) .26 Insurance, n (%) 245 .045  Uninsured 2 (1) 1 (1)  Medicare 64 (40) 40 (49)  Medicaid 3 (2) 3 (4)  VA/Government 4 (2) 7 (9)  Private 90 (55) 31 (38) ASA, american society of anesthesiologists; BMI, body mass index; CAD, coronary artery disease; VA, Veteran's affairs. Bold denotes statistical significance. View Large TABLE 1. Patient Demographics and Comorbidities by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Age, median (IQR) 245 61 (54-69) 66 (57-72) <.001 Male gender, n (%) 245 76 (47) 41 (52) .62 BMI, median (IQR) 245 31 (26-34) 30 (26-33) .43 Race, n (%) 245 .32  White 138 (85) 63 (77)  Other 25 (15) 19 (20) Education, n (%) 241 <.001  Less than high school 6 (4) 13 (16)  High school diploma 78 (49) 31 (38)  Two-year college degree 42 (26) 10 (12)  Four-year college degree 21 (13) 10 (12)  Postcollege 13 (8) 17 (21) Smoking, n (%) 242 36 (22) 17 (21) .81 CAD, n (%) 245 18 (11) 8 (10) .76 Diabetes, n (%) 245 27 (17) 14 (17) .92 Depression, n (%) 245 .031  Moderate 58 (36) 41 (50)  Extreme 25 (15) 5 (6) ASA, n (%) 245 .68  1/2 75 (46) 40 (49)  3/4 88 (54) 42 (51) Employment, n (%) 245 .12  Sedentary 12 (7) 11 (13)  Light 24 (15) 8 (10)  Medium 21 (13) 5 (6)  Heavy 14 (9) 4 (5)  Unemployed/attending school 92 (56) 54 (66) Worker's Compensation, n (%) 242 3 (2) 1 (1) .72 Liability, n (%) 242 9 (6) 2 (2) .26 Insurance, n (%) 245 .045  Uninsured 2 (1) 1 (1)  Medicare 64 (40) 40 (49)  Medicaid 3 (2) 3 (4)  VA/Government 4 (2) 7 (9)  Private 90 (55) 31 (38) Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Age, median (IQR) 245 61 (54-69) 66 (57-72) <.001 Male gender, n (%) 245 76 (47) 41 (52) .62 BMI, median (IQR) 245 31 (26-34) 30 (26-33) .43 Race, n (%) 245 .32  White 138 (85) 63 (77)  Other 25 (15) 19 (20) Education, n (%) 241 <.001  Less than high school 6 (4) 13 (16)  High school diploma 78 (49) 31 (38)  Two-year college degree 42 (26) 10 (12)  Four-year college degree 21 (13) 10 (12)  Postcollege 13 (8) 17 (21) Smoking, n (%) 242 36 (22) 17 (21) .81 CAD, n (%) 245 18 (11) 8 (10) .76 Diabetes, n (%) 245 27 (17) 14 (17) .92 Depression, n (%) 245 .031  Moderate 58 (36) 41 (50)  Extreme 25 (15) 5 (6) ASA, n (%) 245 .68  1/2 75 (46) 40 (49)  3/4 88 (54) 42 (51) Employment, n (%) 245 .12  Sedentary 12 (7) 11 (13)  Light 24 (15) 8 (10)  Medium 21 (13) 5 (6)  Heavy 14 (9) 4 (5)  Unemployed/attending school 92 (56) 54 (66) Worker's Compensation, n (%) 242 3 (2) 1 (1) .72 Liability, n (%) 242 9 (6) 2 (2) .26 Insurance, n (%) 245 .045  Uninsured 2 (1) 1 (1)  Medicare 64 (40) 40 (49)  Medicaid 3 (2) 3 (4)  VA/Government 4 (2) 7 (9)  Private 90 (55) 31 (38) ASA, american society of anesthesiologists; BMI, body mass index; CAD, coronary artery disease; VA, Veteran's affairs. Bold denotes statistical significance. View Large TABLE 2. Baseline Symptoms, Diagnoses, and PRO Scores by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Symptom duration, n (%) 237 .63  Less than 3 mo 15 (9) 10 (13)  3-12 mo 67 (42) 32 (42)  More than 12 mo 79 (49) 34 (45) Motor deficit present, n (%) 245 86 (53) 49 (60) .30 Numbness present, n (%) 245 87 (53) 4 (51) .75 Independent ambulation, n (%) 245 143 (88) 65 (79) .08 Diagnosis, n (%) 245 .014  Disc herniation 25 (15) 3 (4)  Foraminal stenosis 37 (23) 16 (20)  Central stenosis 101 (62) 63 (77) Baseline PROs, median (IQR)  NDI 245 38 (28-52) 37 (20-50) .19  EQ5D 245 0.69 (0.44-0.78) 0.6 (0.47-0.78) .77  NRS-neck pain 245 6 (3-8) 5 (2-7) .16  NRS-arm pain 245 5 (2-8) 5 (2-7) .24  mJOA 241 13 (11-14) 12 (10-14) .02 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Symptom duration, n (%) 237 .63  Less than 3 mo 15 (9) 10 (13)  3-12 mo 67 (42) 32 (42)  More than 12 mo 79 (49) 34 (45) Motor deficit present, n (%) 245 86 (53) 49 (60) .30 Numbness present, n (%) 245 87 (53) 4 (51) .75 Independent ambulation, n (%) 245 143 (88) 65 (79) .08 Diagnosis, n (%) 245 .014  Disc herniation 25 (15) 3 (4)  Foraminal stenosis 37 (23) 16 (20)  Central stenosis 101 (62) 63 (77) Baseline PROs, median (IQR)  NDI 245 38 (28-52) 37 (20-50) .19  EQ5D 245 0.69 (0.44-0.78) 0.6 (0.47-0.78) .77  NRS-neck pain 245 6 (3-8) 5 (2-7) .16  NRS-arm pain 245 5 (2-8) 5 (2-7) .24  mJOA 241 13 (11-14) 12 (10-14) .02 IQR, interquartile range; NDI, neck disability index; NRS, numeric rating scale; mJOA, modified Japanese Orthopedic Association. Bold denotes statistical significance. View Large TABLE 2. Baseline Symptoms, Diagnoses, and PRO Scores by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Symptom duration, n (%) 237 .63  Less than 3 mo 15 (9) 10 (13)  3-12 mo 67 (42) 32 (42)  More than 12 mo 79 (49) 34 (45) Motor deficit present, n (%) 245 86 (53) 49 (60) .30 Numbness present, n (%) 245 87 (53) 4 (51) .75 Independent ambulation, n (%) 245 143 (88) 65 (79) .08 Diagnosis, n (%) 245 .014  Disc herniation 25 (15) 3 (4)  Foraminal stenosis 37 (23) 16 (20)  Central stenosis 101 (62) 63 (77) Baseline PROs, median (IQR)  NDI 245 38 (28-52) 37 (20-50) .19  EQ5D 245 0.69 (0.44-0.78) 0.6 (0.47-0.78) .77  NRS-neck pain 245 6 (3-8) 5 (2-7) .16  NRS-arm pain 245 5 (2-8) 5 (2-7) .24  mJOA 241 13 (11-14) 12 (10-14) .02 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Symptom duration, n (%) 237 .63  Less than 3 mo 15 (9) 10 (13)  3-12 mo 67 (42) 32 (42)  More than 12 mo 79 (49) 34 (45) Motor deficit present, n (%) 245 86 (53) 49 (60) .30 Numbness present, n (%) 245 87 (53) 4 (51) .75 Independent ambulation, n (%) 245 143 (88) 65 (79) .08 Diagnosis, n (%) 245 .014  Disc herniation 25 (15) 3 (4)  Foraminal stenosis 37 (23) 16 (20)  Central stenosis 101 (62) 63 (77) Baseline PROs, median (IQR)  NDI 245 38 (28-52) 37 (20-50) .19  EQ5D 245 0.69 (0.44-0.78) 0.6 (0.47-0.78) .77  NRS-neck pain 245 6 (3-8) 5 (2-7) .16  NRS-arm pain 245 5 (2-8) 5 (2-7) .24  mJOA 241 13 (11-14) 12 (10-14) .02 IQR, interquartile range; NDI, neck disability index; NRS, numeric rating scale; mJOA, modified Japanese Orthopedic Association. Bold denotes statistical significance. View Large Table 3 summarizes comparison of hospital LOS, complications, 90-d readmission, and 12-mo reoperation rates for anterior and posterior approach for degenerative cervical myelopathy. Patients undergoing posterior surgery had a longer median LOS by 2 d compared to those undergoing anterior surgery (3 vs 1, P < .001). Although not significant, overall complication risk was slightly higher in the anterior group (10% vs 7%, P = .52). There were no statistically significant differences in 90-d readmission (anterior-9% vs posterior-7%, P = .62) and RTW (anterior-66% vs posterior-76%, P = .34) as well as 12-mo reoperation (anterior-1% vs posterior-1%, P > .99). Patients in the posterior cohort were more likely to report worse 12-mo mJOA scores (median: 14 vs 15, P = .002). There were no significant differences in the PROs between the 2 groups (Table 4). TABLE 3. Summary of Operative Variables and Postoperative Outcomes Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Operative variables Estimated blood loss in ml, median (IQR) 221 100 (50-150) 200 (100-300) <.001 Operative time in min, median (IQR) 245 166 (125-216) 143 (112-178) .009 Number of levels, n (%) 245  3 120 (74) 29 (35) <.001  4 40 (25) 40 (49)  5 3 (2) 13 (16) Postoperative variables LOS, days, median (IQR) 245 1 (1-3) 3 (2-4) <.001 Any adverse eventa, n (%) 245 25 (15) 10 (12) .51 Any complication, n (%) 245 16 (10) 6 (7) .52 Deep venous thrombosis, n (%) 245 0 (0) 1 (1) .16 Pulmonary embolism, n (%) 245 0 (0) 1 (1) .16 Myocardial infarction, n (%) 245 0 (0) 0 (0) NA Urinary tract infection, n (%) 245 1 (1) 1 (1) .62 Surgical site infection, n (%) 245 1 (1) 1 (1) .62 Hematoma, n (%) 245 0 (0) 2 (1) .31 Dysphagia requiring nasogastric tube, n (%) 245 2 (1) 0 (0) .31 Dysphagia not requiring nasogastric tube, n (%) 245 8 (5) 1 (1) .15 Vocal cord paralysis, n (%) 245 0 (0) 0 (0) NA CSF leak, n (%) 245 0 (0) 1 (1) .16 Wound dehiscence, n (%) 245 1 (1) 1 (1) .62 CVA within 30 d, n (%) 245 0 (0) 0 (0) NA New motor deficit, n (%) 245 2 (4) 0 (0) .33 Readmission within 90 d, n (%) 245 15 (9) 6 (7) .62 RTW within 90 d, n (%) 103 49 (69) 22 (76) .34 Reoperation within 12 mo, n (%) 245 2 (1) 1 (1) >.99 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Operative variables Estimated blood loss in ml, median (IQR) 221 100 (50-150) 200 (100-300) <.001 Operative time in min, median (IQR) 245 166 (125-216) 143 (112-178) .009 Number of levels, n (%) 245  3 120 (74) 29 (35) <.001  4 40 (25) 40 (49)  5 3 (2) 13 (16) Postoperative variables LOS, days, median (IQR) 245 1 (1-3) 3 (2-4) <.001 Any adverse eventa, n (%) 245 25 (15) 10 (12) .51 Any complication, n (%) 245 16 (10) 6 (7) .52 Deep venous thrombosis, n (%) 245 0 (0) 1 (1) .16 Pulmonary embolism, n (%) 245 0 (0) 1 (1) .16 Myocardial infarction, n (%) 245 0 (0) 0 (0) NA Urinary tract infection, n (%) 245 1 (1) 1 (1) .62 Surgical site infection, n (%) 245 1 (1) 1 (1) .62 Hematoma, n (%) 245 0 (0) 2 (1) .31 Dysphagia requiring nasogastric tube, n (%) 245 2 (1) 0 (0) .31 Dysphagia not requiring nasogastric tube, n (%) 245 8 (5) 1 (1) .15 Vocal cord paralysis, n (%) 245 0 (0) 0 (0) NA CSF leak, n (%) 245 0 (0) 1 (1) .16 Wound dehiscence, n (%) 245 1 (1) 1 (1) .62 CVA within 30 d, n (%) 245 0 (0) 0 (0) NA New motor deficit, n (%) 245 2 (4) 0 (0) .33 Readmission within 90 d, n (%) 245 15 (9) 6 (7) .62 RTW within 90 d, n (%) 103 49 (69) 22 (76) .34 Reoperation within 12 mo, n (%) 245 2 (1) 1 (1) >.99 CSF, cerebrospinal fluid leak; CVA, cerebrovascular accident; NDI, neck disability index; NRS, numeric rating scale; mJOA, modified Japanese Orthopedic Association. aAdverse event is defined as the occurrence of any complication, readmission, or reoperation. Bold denotes statistical significance. View Large TABLE 3. Summary of Operative Variables and Postoperative Outcomes Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Operative variables Estimated blood loss in ml, median (IQR) 221 100 (50-150) 200 (100-300) <.001 Operative time in min, median (IQR) 245 166 (125-216) 143 (112-178) .009 Number of levels, n (%) 245  3 120 (74) 29 (35) <.001  4 40 (25) 40 (49)  5 3 (2) 13 (16) Postoperative variables LOS, days, median (IQR) 245 1 (1-3) 3 (2-4) <.001 Any adverse eventa, n (%) 245 25 (15) 10 (12) .51 Any complication, n (%) 245 16 (10) 6 (7) .52 Deep venous thrombosis, n (%) 245 0 (0) 1 (1) .16 Pulmonary embolism, n (%) 245 0 (0) 1 (1) .16 Myocardial infarction, n (%) 245 0 (0) 0 (0) NA Urinary tract infection, n (%) 245 1 (1) 1 (1) .62 Surgical site infection, n (%) 245 1 (1) 1 (1) .62 Hematoma, n (%) 245 0 (0) 2 (1) .31 Dysphagia requiring nasogastric tube, n (%) 245 2 (1) 0 (0) .31 Dysphagia not requiring nasogastric tube, n (%) 245 8 (5) 1 (1) .15 Vocal cord paralysis, n (%) 245 0 (0) 0 (0) NA CSF leak, n (%) 245 0 (0) 1 (1) .16 Wound dehiscence, n (%) 245 1 (1) 1 (1) .62 CVA within 30 d, n (%) 245 0 (0) 0 (0) NA New motor deficit, n (%) 245 2 (4) 0 (0) .33 Readmission within 90 d, n (%) 245 15 (9) 6 (7) .62 RTW within 90 d, n (%) 103 49 (69) 22 (76) .34 Reoperation within 12 mo, n (%) 245 2 (1) 1 (1) >.99 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Operative variables Estimated blood loss in ml, median (IQR) 221 100 (50-150) 200 (100-300) <.001 Operative time in min, median (IQR) 245 166 (125-216) 143 (112-178) .009 Number of levels, n (%) 245  3 120 (74) 29 (35) <.001  4 40 (25) 40 (49)  5 3 (2) 13 (16) Postoperative variables LOS, days, median (IQR) 245 1 (1-3) 3 (2-4) <.001 Any adverse eventa, n (%) 245 25 (15) 10 (12) .51 Any complication, n (%) 245 16 (10) 6 (7) .52 Deep venous thrombosis, n (%) 245 0 (0) 1 (1) .16 Pulmonary embolism, n (%) 245 0 (0) 1 (1) .16 Myocardial infarction, n (%) 245 0 (0) 0 (0) NA Urinary tract infection, n (%) 245 1 (1) 1 (1) .62 Surgical site infection, n (%) 245 1 (1) 1 (1) .62 Hematoma, n (%) 245 0 (0) 2 (1) .31 Dysphagia requiring nasogastric tube, n (%) 245 2 (1) 0 (0) .31 Dysphagia not requiring nasogastric tube, n (%) 245 8 (5) 1 (1) .15 Vocal cord paralysis, n (%) 245 0 (0) 0 (0) NA CSF leak, n (%) 245 0 (0) 1 (1) .16 Wound dehiscence, n (%) 245 1 (1) 1 (1) .62 CVA within 30 d, n (%) 245 0 (0) 0 (0) NA New motor deficit, n (%) 245 2 (4) 0 (0) .33 Readmission within 90 d, n (%) 245 15 (9) 6 (7) .62 RTW within 90 d, n (%) 103 49 (69) 22 (76) .34 Reoperation within 12 mo, n (%) 245 2 (1) 1 (1) >.99 CSF, cerebrospinal fluid leak; CVA, cerebrovascular accident; NDI, neck disability index; NRS, numeric rating scale; mJOA, modified Japanese Orthopedic Association. aAdverse event is defined as the occurrence of any complication, readmission, or reoperation. Bold denotes statistical significance. View Large TABLE 4. Summary of 12-mo Patient-Reported Outcomes by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value NASS satisfaction 245 .70  1 98 (60) 50 (62)  2 39 (24) 15 (19)  3 15 (9) 9 (11)  4 10 (6) 7 (9) NDI, median (IQR) 245 16 (6-29) 17 (8-28) .41 EQ-5D, median (IQR) 245 0.82 (0.69-0.86) 0.78 (0.69-0.83) .25 NRS-neck pain, median (IQR) 245 2 (0-4) 2 (1-4) .31 NRS-arm pain, median (IQR) 245 1 (0-4) 0.5 (0-5) .87 mJOA, median (IQR) 253 15 (13-17) 14 (12-16) .002 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value NASS satisfaction 245 .70  1 98 (60) 50 (62)  2 39 (24) 15 (19)  3 15 (9) 9 (11)  4 10 (6) 7 (9) NDI, median (IQR) 245 16 (6-29) 17 (8-28) .41 EQ-5D, median (IQR) 245 0.82 (0.69-0.86) 0.78 (0.69-0.83) .25 NRS-neck pain, median (IQR) 245 2 (0-4) 2 (1-4) .31 NRS-arm pain, median (IQR) 245 1 (0-4) 0.5 (0-5) .87 mJOA, median (IQR) 253 15 (13-17) 14 (12-16) .002 mJOA, modified Japanese Orthopedic Association; NASS, North American Spine Society; NDI, Neck Disability Index; NRS, Numeric rating scale. Bold denotes statistical significance. View Large TABLE 4. Summary of 12-mo Patient-Reported Outcomes by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value NASS satisfaction 245 .70  1 98 (60) 50 (62)  2 39 (24) 15 (19)  3 15 (9) 9 (11)  4 10 (6) 7 (9) NDI, median (IQR) 245 16 (6-29) 17 (8-28) .41 EQ-5D, median (IQR) 245 0.82 (0.69-0.86) 0.78 (0.69-0.83) .25 NRS-neck pain, median (IQR) 245 2 (0-4) 2 (1-4) .31 NRS-arm pain, median (IQR) 245 1 (0-4) 0.5 (0-5) .87 mJOA, median (IQR) 253 15 (13-17) 14 (12-16) .002 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value NASS satisfaction 245 .70  1 98 (60) 50 (62)  2 39 (24) 15 (19)  3 15 (9) 9 (11)  4 10 (6) 7 (9) NDI, median (IQR) 245 16 (6-29) 17 (8-28) .41 EQ-5D, median (IQR) 245 0.82 (0.69-0.86) 0.78 (0.69-0.83) .25 NRS-neck pain, median (IQR) 245 2 (0-4) 2 (1-4) .31 NRS-arm pain, median (IQR) 245 1 (0-4) 0.5 (0-5) .87 mJOA, median (IQR) 253 15 (13-17) 14 (12-16) .002 mJOA, modified Japanese Orthopedic Association; NASS, North American Spine Society; NDI, Neck Disability Index; NRS, Numeric rating scale. Bold denotes statistical significance. View Large In risk-adjusted multivariable analysis, within the limits of baseline variables included in the model, the patients undergoing anterior approach had lower odds of having higher LOS (P < .001, OR 0.16, 95% CI 0.08-0.30; Table 5). The effect of anterior vs posterior approach was not found to be significant for 90-d readmission (P = .17, OR 0.32, 95% CI 0.06-1.66), 90-d RTW (P = .07, HR 0.40, 95% CI 0.1-1.08) or 12-mo NDI (P = .36, OR 0.76, 95% CI 0.42-1.37), EQ-5D (P = .30, OR 1.36, 95% CI 0.76-2.44), NRS-neck (P = .19, OR 0.67, 95% CI 0.37-1.21) and -arm pain scores (P = .96, OR 0.99, 95% CI 0.51-1.93), mJOA scores (P = .08, OR 1.74, 95% CI 0.94-3.24), and satisfaction (P = .43, OR 1.34, 95% CI 0.64-2.85). TABLE 5. Adjusted OR (Hazard Ratio) of Approach on Outcomes Outcome OR/Hazards ratio 95% CI P-value 12m NDI 0.76 0.42 - 1.37 .36 12m EQ5D 1.36 0.76 - 2.44 .30 12m NRS-neck pain 0.67 0.37 - 1.21 .19 12m NRS-arm pain 0.99 0.51 - 1.93 .96 12m mJOA 1.74 0.94 - 3.24 .08 12m patient satisfaction 1.34 0.64 - 2.85 .43 LOS 0.16 0.08 - 0.30 <.001 90-d readmission 0.32 0.06 - 1.66 .17 RTW within 3 mo 0.40 0.16 - 1.08 .07 Outcome OR/Hazards ratio 95% CI P-value 12m NDI 0.76 0.42 - 1.37 .36 12m EQ5D 1.36 0.76 - 2.44 .30 12m NRS-neck pain 0.67 0.37 - 1.21 .19 12m NRS-arm pain 0.99 0.51 - 1.93 .96 12m mJOA 1.74 0.94 - 3.24 .08 12m patient satisfaction 1.34 0.64 - 2.85 .43 LOS 0.16 0.08 - 0.30 <.001 90-d readmission 0.32 0.06 - 1.66 .17 RTW within 3 mo 0.40 0.16 - 1.08 .07 NRS: numeric rating scale; NDI: neck disability index; mJOA: modified Japanese Orthopedic Association. Bold denotes statistical significance. View Large TABLE 5. Adjusted OR (Hazard Ratio) of Approach on Outcomes Outcome OR/Hazards ratio 95% CI P-value 12m NDI 0.76 0.42 - 1.37 .36 12m EQ5D 1.36 0.76 - 2.44 .30 12m NRS-neck pain 0.67 0.37 - 1.21 .19 12m NRS-arm pain 0.99 0.51 - 1.93 .96 12m mJOA 1.74 0.94 - 3.24 .08 12m patient satisfaction 1.34 0.64 - 2.85 .43 LOS 0.16 0.08 - 0.30 <.001 90-d readmission 0.32 0.06 - 1.66 .17 RTW within 3 mo 0.40 0.16 - 1.08 .07 Outcome OR/Hazards ratio 95% CI P-value 12m NDI 0.76 0.42 - 1.37 .36 12m EQ5D 1.36 0.76 - 2.44 .30 12m NRS-neck pain 0.67 0.37 - 1.21 .19 12m NRS-arm pain 0.99 0.51 - 1.93 .96 12m mJOA 1.74 0.94 - 3.24 .08 12m patient satisfaction 1.34 0.64 - 2.85 .43 LOS 0.16 0.08 - 0.30 <.001 90-d readmission 0.32 0.06 - 1.66 .17 RTW within 3 mo 0.40 0.16 - 1.08 .07 NRS: numeric rating scale; NDI: neck disability index; mJOA: modified Japanese Orthopedic Association. Bold denotes statistical significance. View Large DISCUSSION Decision making for the treatment of degenerative cervical myelopathy can be challenging for treating spinal surgeons, as surgical complexity, blood loss, operative time, and the incidence of complications increase significantly with the number of involved surgical segments.22,23 In this study, we performed a retrospective analysis of prospectively collected data from multiple surgical practices across the US. With over 250 patients undergoing 3to 5 level fusion surgery for degenerative cervical myelopathy and employing robust statistical methodology, our study is the largest to report postoperative and functional outcomes in this group of patients. After adjusting for a number of preoperative and operative variables, the patients undergoing ACDF with or without corpectomy had lower odds of having longer LOS compared to those undergoing posterior fusion. The 12-mo PROs, 90-d readmission and RTW were statistically similar between the groups. The literature on PROs following multilevel fusion surgery for degenerative cervical myelopathy is sparse. Similar to our analysis, the AOSpine North America cervical myelopathy study (nonrandomized, prospective study involving 278 patients from 12 US sites) demonstrated that patients with degenerative cervical myelopathy failed to detect any difference with regards to PRO scores at 12 mo between the 2 approaches.4 The authors included patients undergoing single-level as well as multilevel anterior and posterior fusion. Our analysis was focused on patients undergoing fusion at 3 to 5 levels; therefore, allowing to compare the approach in more homogenous population. Kristof and colleagues,22 in a large, single-institutional study of 103 patients, found that patients with multilevel disease treated with laminectomy and fusion compared favorably with patients treated with an anterior approach. Postoperative outcomes, including change in Nurick myelopathy scores, change in Visual Analog neck pain Scale, and satisfaction with treatment did not differ between the 2 groups at last follow-up (at least 1 yr). Finally, a recently published study by Kato and colleagues25 analyzed 435 patients enrolled in 2 international AOSpine cervical spondylotic myelopathy (CSM) studies. Following magnetic resonance imaging-based 1-to-1 propensity score matching analysis, the authors found that anterior and posterior groups did not differ significantly in terms of the postoperative mJOA score, NDI disability Index, and Short Form-36 Physical Component Summary score. In our analysis, patients undergoing a posterior approach spent on average 2 more days in the hospital, an observation that has been reported by previous prospective studies as well.5,26 This is an expected finding given the older age of the patients and the more extensive nature of the procedure, as levels of surgery and intraoperative blood loss were higher in posterior cervical fusion group. Both the anterior and posterior cervical fusions are associated with complications.27-31 A recent systematic review and meta-analysis found the complication and reoperation rates to be significantly higher in the anterior group, with the most common causes being graft nonunion and adjacent segment disease.32 In our cohort, we found that the complications including dysphagia, surgical site hematoma, and new neurological deficit were higher in anterior group, whereas pulmonary embolism, deep venous thrombosis, and cerebrospinal fluid leak were higher in the posterior group. However, there was no significant difference in overall complications, readmission, or 12-mo reoperation rate between the groups. In the study by Kato et al,25 the overall rates of perioperative complications were similar between the 2 groups (16% vs 11%); interestingly, dysphagia, and dysphonia were reported only in the anterior group, whereas surgical site infection and C5 radiculopathy were reported only in the posterior group.25 Although relatively rare, previous studies have found the anterior approaches to be relatively cost-effective compared to the posterior approaches.33,34 Specifically, Whitmore and colleagues33 analyzed 85 patients with CSM, aged 40 to 85 yr, across 7 sites. The authors investigated multiple different carotid endarterectomy methods, including Medicare cost-to-charge ratios and Medicare coding reimbursement, and consistently found ventral approaches to be more cost-effective compared to dorsal approaches (approximately $34 533).33 Similarly, Fehlings and colleagues34 analyzed 70 patients undergoing surgery for CSM at a single institution in Canada and found that the cost-utility ratio for CSM surgeries to be $32 916/ quality-adjusted life years, which is below the national benchmark to be considered highly cost-effective. Ultimately, the surgeon's familiarity and comfort with the surgical technique is a key element to be considered in decision-making. Surgeons generally prefer to treat patients with focal pathology, eg intervertebral disc herniation, using an anterior approach. Similarly, our data revealed that patients in the anterior group had a higher percentage of herniated disc than patients in the posterior group. In such cases, anterior surgery allows for better decompression of the spinal cord and improvement in myelopathy symptoms. It is important to note that arthrodesis-related variables, such as the inclusion of C7 vertebra in the multilevel constructs or development of pseudarthrosis, are not included in QOD, therefore their impact on 12-mo PROs could not be determined. Nevertheless, only 4 patients (2 in the anterior group and 2 in the posterior group) underwent revision surgery within the first 12 mo. Similarly, radiographic parameters, including T1 slope or C2-C7 lordosis, are not being captured in the spine module of QOD. These variables were included in the first version of the module; however, they were subsequently removed and are being redesigned for future versions of the spine module. Finally, given the national attention on opioid utilization and addiction, future prospective cohort studies and RCTs should incorporate postoperative opioid prescription rate as an outcome when evaluating the comparative effectiveness of different surgical approaches. Relevant variables, including opioid type, length of prescription, and dose in oral morphine milligram equivalents are currently being designed and scheduled to be released in a new, pilot version. Overall, as our knowledge on the registry's capabilities and challenges grows, there is increasing recognition of the importance of capturing a broader disease portrait with these additional data elements that can further enhance inference using real-world, observational data. Limitations This study has some limitations. First, it is a nonrandomized study and the type of surgical procedure to be performed is surgeon dependent. Given the risk for selection bias for performing one procedure over the other, future research should also focus on the factors that lead surgeons to perform anterior vs posterior surgery. A previous survey study of 91 spinal surgeons across the US showed that there is a remarkable equipoise in selection of surgical approach in patients with CSM, with the exception of C2-C7 kyphosis >5°, segmental kyphotic deformity, age over 85 yr, ossification of the posterior longitudinal ligament, and congenital canal stenosis.35 Furthermore, the results of this study should be viewed within the context of limitations of adjusting for possible confounding by indication using the baseline variables, ie there could be alternative explanations for the observed differences due to variables not included in the analysis, such as socioeconomic variables, and associated imaging findings, which may be useful in assessing patient disease severity. Second, radiographic parameters, as aforementioned, are not available in the QOD registry. As such, we could not incorporate these variables in the analysis. Nevertheless, the impact of these parameters on postoperative patient-reported outcomes has not yet been fully elucidated. According to previous work, cervical sagittal balance seems to influence only the presentation of pain and the severity of myelopathy.36 In addition, surgical treatment improved pain and mJOA scores regardless of radiographic parameters and baseline sagittal balance. Therefore, the effect of radiographic parameters on the surgical outcomes of interest remains to be determined. Third, we are limited by the 12-mo follow-up duration and the follow-up rate (71%), which is lower than the threshold of 80% that is typically set in prospective studies to ensure that the validity of findings is not threatened. However, this is not an uncommon finding in real-world registries. To address this concern, when we conducted responder/nonresponder analysis, similar patient profiles were found between the 2 groups. More importantly, this is the largest study analyzing the outcomes for patients undergoing 3 to 5 level fusion for degenerative cervical myelopathy. Fourth, given the real-world nature of our registry, standardization of the radiographic evaluations is not feasible. CONCLUSION Patients undergoing anterior approaches for 3 to 5 level degenerative cervical myelopathy had shorter hospital LOS compared to those undergoing posterior decompression and fusion. Also, patients in both groups exhibited similar long term PROs, readmission, and RTW rates. Further investigations are needed to compare the differences in longer term reoperation rates and functional outcomes before the clinical superiority of one approach over the other can be established. Disclosures A portion of this work was supported through a grant from the Neurosurgery Research and Education Foundation. The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. REFERENCES 1. Nurick S . The natural history and the results of surgical treatment of the spinal cord disorder associated with cervical spondylosis . Brain . 1972 ; 95 ( 1 ): 101 - 108 . Google Scholar CrossRef Search ADS PubMed 2. Tetreault L , Goldstein CL , Arnold P et al. Degenerative cervical myelopathy: a spectrum of related disorders affecting the aging spine . Neurosurgery . 2015 ; 77 ( suppl 4 ): S51 - S67 . Google Scholar CrossRef Search ADS PubMed 3. Boogaarts HD , Ronald H M . Prevalence of cervical spondylotic myelopathy . Eur Spine J . 2013 ; 24 ( 2 ): 139 - 141 . Google Scholar PubMed 4. Fehlings MG , Barry S , Kopjar B et al. Anterior versus posterior surgical approaches to treat cervical spondylotic myelopathy: outcomes of the prospective multicenter AOSpine North America CSM study in 264 patients . Spine . 2013 ; 38 ( 26 ): 2247 - 2252 . Google Scholar CrossRef Search ADS PubMed 5. Seng C , Tow BPB , Siddiqui MA et al. Surgically treated cervical myelopathy: a functional outcome comparison study between multilevel anterior cervical decompression fusion with instrumentation and posterior laminoplasty . Spine J . 2013 ; 13 ( 7 ): 723 - 731 . Google Scholar CrossRef Search ADS PubMed 6. Luo J , Cao K , Huang S et al. Comparison of anterior approach versus posterior approach for the treatment of multilevel cervical spondylotic myelopathy . Eur Spine J . 2015 ; 24 ( 8 ): 1621 - 1630 . Google Scholar CrossRef Search ADS PubMed 7. Lin D , Zhai W , Lian K , Kang L , Ding Z . Anterior versus posterior approach for four-level cervical spondylotic myelopathy . Orthopedics . 2013 ; 36 ( 11 ): e1431 - e1436 . Google Scholar CrossRef Search ADS PubMed 8. Zhang ZH , Yin H , Yang K et al. Anterior intervertebral disc excision and bone grafting in cervical spondylotic myelopathy . Spine . 1983 ; 8 ( 1 ): 16 - 19 . Google Scholar CrossRef Search ADS PubMed 9. Emery SE , Bolesta MJ , Banks MA , Jones PK . Robinson anterior cervical fusion comparison of the standard and modified techniques . Spine . 1994 ; 19 ( 6 ): 660 - 663 . Google Scholar CrossRef Search ADS PubMed 10. Benzel EC , Lancon J , Kesterson L , Hadden T . Cervical laminectomy and dentate ligament section for cervical spondylotic myelopathy . J Spinal Disord . 1991 ; 4 ( 3 ): 286 - 295 . Google Scholar CrossRef Search ADS PubMed 11. Carol MP , Ducker TB . Cervical spondylitic myelopathies: surgical treatment . J Spinal Disord . 1988 ; 1 ( 1 ): 59 - 65 . Google Scholar CrossRef Search ADS PubMed 12. Kaminsky SB , Clark CR , Traynelis VC . Operative treatment of cervical spondylotic myelopathy and radiculopathy. A comparison of laminectomy and laminoplasty at five year average follow-up . Iowa Orthop J . 2004 ; 24 : 95 -105. Google Scholar PubMed 13. Asher AL , Speroff T , Dittus RS et al. The National Neurosurgery Quality and Outcomes Database (N2QOD): a collaborative North American outcomes registry to advance value-based spine care . Spine . 2014 ; 39 ( 22 suppl 1 ): S106 - S116 . Google Scholar CrossRef Search ADS PubMed 14. McGirt MJ , Speroff T , Dittus RS , Harrell FE Jr , Asher AL . The national neurosurgery quality and outcomes database (N2QOD): general overview and pilot-year project description . Neurosurg Focus . 2013 ; 34 ( 1 ): 1 - 10 . 15. McGirt MJ , Bydon M , Archer KR et al. An analysis from the Quality Outcomes Database, part 1. Disability, quality of life, and pain outcomes following lumbar spine surgery: predicting likely individual patient outcomes for shared decision-making . J Neurosurg Spine . 2017 ; 27 ( 4 ): 357 - 369 . Google Scholar CrossRef Search ADS PubMed 16. Vernon H , Mior S . The Neck Disability Index: a study of reliability and validity . J Manipulative Physiol Ther . 1991 ; 14 ( 7 ): 409 - 415 . Google Scholar PubMed 17. Langley GB , Sheppeard H . The visual analogue scale: its use in pain measurement . Rheumatol Int . 1985 ; 5 ( 4 ): 145 - 148 . Google Scholar CrossRef Search ADS PubMed 18. EuroQol Group . EuroQol-a new facility for the measurement of health-related quality of life . Health Policy . 1990 ; 16 ( 3 ): 199 - 208 . CrossRef Search ADS PubMed 19. Daltroy LH , Cats-Baril WL , Katz JN , Fossel AH , Liang MH . The North American Spine Society lumbar spine outcome assessment instrument: reliability and validity tests . Spine . 1996 ; 21 ( 6 ): 741 - 748 . Google Scholar CrossRef Search ADS PubMed 20. Harrell FE Jr . Regression Modeling Strategies: With Applications to Linear Models, Logistic and Ordinal Regression, and Survival Analysis . Springer-Verlag , Cham ; 2015 . 21. R Core Team . R: A language and environment for statistical computing. R Foundation for Statistical Computing , Vienna, Austria ; 2013 . 22. Zhu B , Xu Y , Liu X , Liu Z , Dang G . Anterior approach versus posterior approach for the treatment of multilevel cervical spondylotic myelopathy: a systemic review and meta-analysis . Eur Spine J . 2013 ; 22 ( 7 ): 1583 - 1593 . Google Scholar CrossRef Search ADS PubMed 23. Komotar RJ , Mocco J , Kaiser MG . Surgical management of cervical myelopathy: indications and techniques for laminectomy and fusion . Spine J . 2006 ; 6 ( 6 ): S252 - S267 . Google Scholar CrossRef Search ADS 24. Kristof RA , Kiefer T , Thudium M et al. Comparison of ventral corpectomy and plate-screw-instrumented fusion with dorsal laminectomy and rod-screw-instrumented fusion for treatment of at least two vertebral-level spondylotic cervical myelopathy . Eur Spine J . 2009 ; 18 ( 12 ): 1951 - 1956 . Google Scholar CrossRef Search ADS PubMed 25. Kato S , Nouri A , Wu D , Nori S , Tetreault L , Fehlings MG . Comparison of anterior and posterior surgery for degenerative cervical myelopathy: an MRI-based propensity-score-matched analysis using data from the prospective multicenter AOSpine CSM North America and international studies . J Bone Joint Surg Am . 2017 ; 99 ( 12 ): 1013 - 1021 . Google Scholar CrossRef Search ADS PubMed 26. Ghogawala Z , Martin B , Benzel EC et al. Comparative effectiveness of ventral vs dorsal surgery for cervical spondylotic myelopathy . Neurosurgery . 2011 ; 68 ( 3 ): 622 - 631 . Google Scholar CrossRef Search ADS PubMed 27. Bydon M , Xu R , Macki M et al. Adjacent segment disease after anterior cervical discectomy and fusion in a large series . Neurosurgery . 2014 ; 74 ( 2 ): 139 - 146 . Google Scholar CrossRef Search ADS PubMed 28. Hosono N , Yonenobu K , Ono K . Neck and shoulder pain after laminoplasty. A noticeable complication . Spine . 1996 ; 21 ( 17 ): 1969 - 1973 . Google Scholar CrossRef Search ADS PubMed 29. Imagama S , Matsuyama Y , Yukawa Y et al. C5 palsy after cervical laminoplasty: a multicentre study . J Bone Joint Surg Br . 2010 ; 92 ( 3 ): 393 - 400 . Google Scholar CrossRef Search ADS PubMed 30. Yue W-M , Brodner W , Highland TR . Long-term results after anterior cervical discectomy and fusion with allograft and plating: a 5- to 11-year radiologic and clinical follow-up study . Spine . 2005 ; 30 ( 19 ): 2138 - 2144 . Google Scholar CrossRef Search ADS PubMed 31. Yonenobu K , Hosono N , Iwasaki M , Asano M , Ono K . Laminoplasty versus subtotal corpectomy. A comparative study of results in multisegmental cervical spondylotic myelopathy . Spine . 1992 ; 17 ( 11 ): 1281 - 1284 . Google Scholar CrossRef Search ADS PubMed 32. Zhu B , Xu Y , Liu X , Liu Z , Dang G . Anterior approach versus posterior approach for the treatment of multilevel cervical spondylotic myelopathy: a systemic review and meta-analysis . Eur Spine J . 2013 ; 22 ( 7 ): 1583 - 1593 . Google Scholar CrossRef Search ADS PubMed 33. Whitmore RG , Schwartz JS , Simmons S , Stein SC , Ghogawala Z . Performing a cost analysis in spine outcomes research: comparing ventral and dorsal approaches for cervical spondylotic myelopathy . Neurosurgery . 2012 ; 70 ( 4 ): 860 - 867 . Google Scholar CrossRef Search ADS PubMed 34. Fehlings MG , Jha NK , Hewson SM , Massicotte EM , Kopjar B , Kalsi-Ryan S . Is surgery for cervical spondylotic myelopathy cost-effective? A cost-utility analysis based on data from the AOSpine North America prospective CSM study . J Neurosurg Spine . 2012 ; 17 ( 1 suppl ): 89 - 93 . Google Scholar CrossRef Search ADS PubMed 35. Ghogawala Z , Coumans J-V , Benzel EC , Stabile LM , Barker FG , Ventral versus dorsal decompression for cervical spondylotic myelopathy: surgeons? Assessment of eligibility for randomization in a proposed randomized controlled trial: results of a survey of the Cervical Spine Research Society . Spine . 2007 ; 32 ( 4 ): 429 - 436 . Google Scholar CrossRef Search ADS PubMed 36. Nicholson K , Millhouse PW , Pflug E et al. Outcomes of treatment for cervical myelopathy . Spine J . 2016 ; 16 ( 10 ): S113 - S114 . Google Scholar CrossRef Search ADS Supplemental digital content is available for this article at www.operativeneurneuros-online.com. Supplemental Digital Content. Table. Comparison of demographics and clinical characteristics between responders and non-responders COMMENTS Degenerative cervical myelopathy (DCM) is a common condition in the elderly. In today's society, with demographic data reflecting the growing senior population, prompt diagnosis and treatment is crucial for this condition. Current operative treatment for DCM includes mainly anterior cervical discectomy or corpectomy and fusion (ACDF or ACCF) and posterior spinal decompression and fusion (PSF). The authors of this article aimed to compare anterior versus posterior surgery in terms of outcome for 3–5 level DCM. The authors conduct a well-organized analysis of a multicenter, prospectively collected dataset examining a very relevant topic that remains controversial in the field of spine surgery today. While controversial, it is generally accepted that ACDF is preferable for focal disease while PSF is used when multilevel long fusion construct is required. The intermediate levels are where controversies exist. Using the Quality Outcomes Database (QOD), the authors of this article reported their assessment of postoperative functional outcome related to surgical approach for DCM. They demonstrated an advantage of reduced length of stay (LOS) with the anterior procedure for 3 to 5 levels fusion. However, 90-day readmission, 12-month NDI, EQ-5D, NRS-neck, arm pain, mJOA, overall complications, return to work, and patient satisfaction were not significantly different between groups. Furthermore, the authors showed that although overall complication rate between the 2 groups were similar, the types of complications were specific to either the anterior or posterior approach. Finally, we applaud the authors on their contribution to our understanding of DCM. Currently there are some generally accepted indications for anterior surgery including ventral pathology, focal disease, and presence of kyphotic deformity. Conversely, the presence of posterior pathology, ossification of the posterior longitudinal ligament, and multilevel stenosis usually favors a decompression and fusion through a posterior approach.1 Previously, the outcome of anterior versus posterior surgery had been shown to be equivalent in a multicenter, prospective observational study by Fehlings et al 2013.2 Hence, there is still no definitive answer as to the best surgical approach for DCM. Surgical decision making is still largely based on surgeon preference, individual experience, and technical comfort. Thus, we believe with ongoing research in this field, we will continue to resolve the controversies and improve our knowledge in the area of DCM. Fan Jiang Michael G. Fehlings Toronto, Canada 1. Wilson JR , Tetreault LA , Kim J et al. State of the Art in Degenerative Cervical Myelopathy: An Update on Current Clinical Evidence . Neurosurgery 2017 ; 80 : S33 - S45 . Google Scholar CrossRef Search ADS PubMed 2. Fehlings MG , Barry S , Kopjar B et al. Anterior versus posterior surgical approaches to treat cervical spondylotic myelopathy: outcomes of the prospective multicenter AOSpine North America CSM study in 264 patients . Spine (Phila Pa 1976) 2013 ; 38 : 2247 - 52 . Copyright © 2018 by the Congress of Neurological Surgeons This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Neurosurgery Oxford University Press

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Abstract

Abstract BACKGROUND The choice of anterior vs posterior approach for degenerative cervical myelopathy that spans multiple segments remains controversial. OBJECTIVE To compare the outcomes following the 2 approaches using multicenter prospectively collected data. METHODS Quality Outcomes Database (QOD) for patients undergoing surgery for 3 to 5 level degenerative cervical myelopathy was analyzed. The anterior group (anterior cervical discectomy [ACDF] or corpectomy [ACCF] with fusion) was compared with posterior cervical fusion. Outcomes included: patient reported outcomes (PROs): neck disability index (NDI), numeric rating scale (NRS) of neck pain and arm pain, EQ-5D, modified Japanese Orthopedic Association score for myelopathy (mJOA), and NASS satisfaction questionnaire; hospital length of stay (LOS), 90-d readmission, and return to work (RTW). Multivariable regression models were fitted for outcomes. RESULTS Of total 245 patients analyzed, 163 patients underwent anterior surgery (ACDF-116, ACCF-47) and 82 underwent posterior surgery. Patients undergoing an anterior approach had lower odds of having higher LOS (P < .001, odds ratio 0.16, 95% confidence interval 0.08-0.30). The 12-mo NDI, EQ-5D, NRS, mJOA, and satisfaction scores as well as 90-d readmission and RTW did not differ significantly between anterior and posterior groups. CONCLUSION Patients undergoing anterior approaches for 3 to 5 level degenerative cervical myelopathy had shorter hospital LOS compared to those undergoing posterior decompression and fusion. Also, patients in both groups exhibited similar long-term PROs, readmission, and RTW rates. Further investigations are needed to compare the differences in longer term reoperation rates and functional outcomes before the clinical superiority of one approach over the other can be established. Cervical myelopathy, Anterior discectomy and fusion, Posterior cervical fusion, Quality outcomes database, Neurosurgical registry ABBREVIATIONS ABBREVIATIONS ACCF anterior cervical corpectomy and fusion ACDF anterior cervical discectomy and fusion ASA American Society of Anesthesiologists BMI body mass index CAD coronary artery disease CI confidence interval CSM cervical spondylotic myelopathy EQ-5D EuroQol-5D HR hazard ratio LOS length of stay mJOA modified Japanese Orthopedic Association NDI Neck Disability Index NRS numeric rating scale OR odds ratio PROs patient-reported outcomes QOD Quality Outcomes Database RTW return to work US United States Degenerative cervical myelopathy is the most common cause of acquired neurological disability in people older than 50 yr of age.1 It may be attributed to an array of degenerative changes occurring in the aging spine, including degenerative disc disease, facet joint arthritis, ligamentum flavum hypertrophy, and ossification of the posterior longitudinal ligament.2 According to a report published in 2009, degenerative cervical myelopathy is the most common primary diagnosis (36%) among elderly patients admitted to a hospital between 1992 and 2005 in the United States (US) to undergo surgical treatment for degenerative cervical spine disease.3 Surgical management is the treatment of choice in cases of progressive or severe neurological deficits. However, the optimal approach, ie anterior vs posterior, still remains an area of contention among surgeons.4-7 Anterior decompressive approaches typically involve anterior cervical discectomy and fusion (ACDF) or anterior cervical corpectomy and fusion (ACCF), whereas posterior approaches comprise laminoplasty or laminectomy with or without arthrodesis. In general, an anterior approach is preferred in cases of ventral compression occupying few levels while attempting to restore cervical lordosis.4 Previous studies have reported up to 90% fusion rates and significant clinical improvement following ACDF for single-level cervical myelopathy;8,9 however, for the multisegments (≥3) cervical myelopathy the evidence on the relative efficacy of different treatment modalities is still unclear.10-12 To address this gap in current knowledge, we conducted an analysis of prospectively collected data from a multicenter spine registry to determine the outcomes following anterior and posterior approach for patients undergoing multilevel fusion for degenerative cervical myelopathy. METHODS We queried the Quality Outcomes Database (QOD) registry for patients undergoing 3 to 5 level cervical spine surgery for primary indication of degenerative cervical myelopathy. An approval for the study and waiver of informed consent was obtained from the institutional review board. The QOD is a prospective registry, enrolling patients since 2012, and is designed to evaluate risk-adjusted expected morbidity and 12-mo outcomes with the aim of improving efficiency and quality of care for the most commonly performed spinal surgical procedures.13,14 The cervical spine module was developed in 2013, enrolling patients undergoing surgery for degenerative cervical spine disease. Inclusion and Exclusion Criteria The general inclusion and exclusion criteria for the QOD spine modules are described previously.13-15 For this analysis, patients presenting with myelopathy and undergoing equal to or more than 3-levels surgery with at least 12 mo of follow-up were eligible for inclusion in the study. The clinical variables and outcomes were compared between those undergoing anterior or posterior approach. Anterior approaches consisted of ACDF with and without corpectomy, whereas posterior approaches consisted of posterior cervical decompression with instrumented fusion. Outcomes of Interest Baseline and postoperative patient-reported outcomes (PROs) including disability, pain, and quality of life are captured at baseline, 3-mo and 12-mo after surgery via self-administration or phone interview. For this study, the outcomes of interest were 12 mo Neck Disability Index (NDI),16 numeric rating scale (NRS) for neck and arm pain,17 EuroQol-5D (EQ-5D),18 modified Japanese Orthopedic Association scale (mJOA),10 and NASS satisfaction questionnaire.19 Other outcomes of interest included hospital length of stay (LOS), 90-d readmission, and return to work (RTW). The occurrence of postoperative complications, including deep venous thrombosis, pulmonary embolism, myocardial infarction, urinary tract infection, surgical site infection, hematoma, dysphagia, vocal cord paralysis, CSF leak, wound dehiscence, cerebrovascular accident within 30 d, and new motor deficit were also compared between the anterior and posterior approach. Statistical Analysis Descriptive statistics (mean, standard deviation, median, and interquartile range for continuous variables; frequency and proportion for categorical variables) were used for patient demographic and comorbidity information as well as baseline symptoms, diagnosis, PRO scores, LOS, readmission, RTW, and complications. Between the 2 surgical approach groups, continuous variables were compared using Wilcoxon Rank Sum test, whereas categorical variables were compared using Pearson's Chi-square. Responder/nonresponder analysis was also performed in order to investigate to compare the baseline profile of patients who completed the 12-mo follow-up evaluation vs those who did not. Multivariable proportional odds ordinal logistic regression models were fitted for NDI, NRS-neck pain, NRS-arm pain, EQ5D, mJOA satisfaction, and LOS; logistic regression model was fitted for readmission, and Cox proportional hazards model was fitted for RTW. The variables included in the models were age, gender, race, body mass index (BMI), American Society of Anesthesiologists (ASA) grades, insurance status, smoking, diabetes, coronary artery disease (CAD), depression, principal diagnosis, presence of motor deficit or numbness, ambulation, duration of symptoms, education level, worker's compensation, employment liability claim, principal symptom, and baseline functional outcome score. The confidence intervals (CI) for the adjusted odds ratio (OR) or hazard ratio (HR) of surgical procedure were computed using profile likelihood method. The analysis was performed using R 3.1.2 and rms package.20,21 RESULTS A total of 363 patients met the inclusion criteria for the study. Of those, 245 patients (anterior-163, posterior-82) had 12-mo follow-up (70.8% follow-up rate) and were further analyzed. In the anterior approach group, 116 patients underwent ACDF and 47 patients underwent corpectomy. On responder analysis, no significant differences were found between patients with and without complete 12-mo follow-up data, except for diabetes (17% vs 29%, P = .012) and number of surgical levels (overall P = .008; Table, Supplemental Digital Content). Patients undergoing anterior surgery were slightly younger (median age 61 vs 66 yr, P < .001); no differences were observed with regards to gender (male: 47% vs 52%, P = .62), BMI distribution (median: 31 vs 30, P = .43), smoking status (22% vs 21%, P = .81), CAD (11% vs 10%, P = .76), diabetes (17% vs 17%, P = .92), and ASA classification (overall P = .68; Table 1). Baseline symptoms, diagnoses, and PROs are presented in Table 2. Patients undergoing anterior surgery were more often diagnosed with intervertebral disc herniation (15% vs 4%) whereas those undergoing posterior surgery had more often central canal stenosis (77% vs 62%; overall P = .014). There was no significant difference in the baseline PROs between the anterior approach and posterior approach group, (median NDI [38 vs 37, P = .19], EQ-5D [0.69 vs 0.6, P = .77], median NRS-neck pain [6 vs 5, P = .16], median NRS-arm pain [5 vs 5, P = .24]), except for mJOA (13 vs 12, P = .02). In terms of number of level fused, patients undergoing anterior surgery were more likely to receive 3-level surgery (74% vs 35%), whereas patients undergoing posterior surgery were more likely to receive 4-level (49% vs 25%) or 5-level fusion (16% vs 2%; overall P < .001). Finally, an anterior approach was associated with relatively lower intraoperative blood loss (100 vs 200 ml, P < .001); operative time was not different between the 2 groups though (166 vs 146 min, P = .06). TABLE 1. Patient Demographics and Comorbidities by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Age, median (IQR) 245 61 (54-69) 66 (57-72) <.001 Male gender, n (%) 245 76 (47) 41 (52) .62 BMI, median (IQR) 245 31 (26-34) 30 (26-33) .43 Race, n (%) 245 .32  White 138 (85) 63 (77)  Other 25 (15) 19 (20) Education, n (%) 241 <.001  Less than high school 6 (4) 13 (16)  High school diploma 78 (49) 31 (38)  Two-year college degree 42 (26) 10 (12)  Four-year college degree 21 (13) 10 (12)  Postcollege 13 (8) 17 (21) Smoking, n (%) 242 36 (22) 17 (21) .81 CAD, n (%) 245 18 (11) 8 (10) .76 Diabetes, n (%) 245 27 (17) 14 (17) .92 Depression, n (%) 245 .031  Moderate 58 (36) 41 (50)  Extreme 25 (15) 5 (6) ASA, n (%) 245 .68  1/2 75 (46) 40 (49)  3/4 88 (54) 42 (51) Employment, n (%) 245 .12  Sedentary 12 (7) 11 (13)  Light 24 (15) 8 (10)  Medium 21 (13) 5 (6)  Heavy 14 (9) 4 (5)  Unemployed/attending school 92 (56) 54 (66) Worker's Compensation, n (%) 242 3 (2) 1 (1) .72 Liability, n (%) 242 9 (6) 2 (2) .26 Insurance, n (%) 245 .045  Uninsured 2 (1) 1 (1)  Medicare 64 (40) 40 (49)  Medicaid 3 (2) 3 (4)  VA/Government 4 (2) 7 (9)  Private 90 (55) 31 (38) Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Age, median (IQR) 245 61 (54-69) 66 (57-72) <.001 Male gender, n (%) 245 76 (47) 41 (52) .62 BMI, median (IQR) 245 31 (26-34) 30 (26-33) .43 Race, n (%) 245 .32  White 138 (85) 63 (77)  Other 25 (15) 19 (20) Education, n (%) 241 <.001  Less than high school 6 (4) 13 (16)  High school diploma 78 (49) 31 (38)  Two-year college degree 42 (26) 10 (12)  Four-year college degree 21 (13) 10 (12)  Postcollege 13 (8) 17 (21) Smoking, n (%) 242 36 (22) 17 (21) .81 CAD, n (%) 245 18 (11) 8 (10) .76 Diabetes, n (%) 245 27 (17) 14 (17) .92 Depression, n (%) 245 .031  Moderate 58 (36) 41 (50)  Extreme 25 (15) 5 (6) ASA, n (%) 245 .68  1/2 75 (46) 40 (49)  3/4 88 (54) 42 (51) Employment, n (%) 245 .12  Sedentary 12 (7) 11 (13)  Light 24 (15) 8 (10)  Medium 21 (13) 5 (6)  Heavy 14 (9) 4 (5)  Unemployed/attending school 92 (56) 54 (66) Worker's Compensation, n (%) 242 3 (2) 1 (1) .72 Liability, n (%) 242 9 (6) 2 (2) .26 Insurance, n (%) 245 .045  Uninsured 2 (1) 1 (1)  Medicare 64 (40) 40 (49)  Medicaid 3 (2) 3 (4)  VA/Government 4 (2) 7 (9)  Private 90 (55) 31 (38) ASA, american society of anesthesiologists; BMI, body mass index; CAD, coronary artery disease; VA, Veteran's affairs. Bold denotes statistical significance. View Large TABLE 1. Patient Demographics and Comorbidities by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Age, median (IQR) 245 61 (54-69) 66 (57-72) <.001 Male gender, n (%) 245 76 (47) 41 (52) .62 BMI, median (IQR) 245 31 (26-34) 30 (26-33) .43 Race, n (%) 245 .32  White 138 (85) 63 (77)  Other 25 (15) 19 (20) Education, n (%) 241 <.001  Less than high school 6 (4) 13 (16)  High school diploma 78 (49) 31 (38)  Two-year college degree 42 (26) 10 (12)  Four-year college degree 21 (13) 10 (12)  Postcollege 13 (8) 17 (21) Smoking, n (%) 242 36 (22) 17 (21) .81 CAD, n (%) 245 18 (11) 8 (10) .76 Diabetes, n (%) 245 27 (17) 14 (17) .92 Depression, n (%) 245 .031  Moderate 58 (36) 41 (50)  Extreme 25 (15) 5 (6) ASA, n (%) 245 .68  1/2 75 (46) 40 (49)  3/4 88 (54) 42 (51) Employment, n (%) 245 .12  Sedentary 12 (7) 11 (13)  Light 24 (15) 8 (10)  Medium 21 (13) 5 (6)  Heavy 14 (9) 4 (5)  Unemployed/attending school 92 (56) 54 (66) Worker's Compensation, n (%) 242 3 (2) 1 (1) .72 Liability, n (%) 242 9 (6) 2 (2) .26 Insurance, n (%) 245 .045  Uninsured 2 (1) 1 (1)  Medicare 64 (40) 40 (49)  Medicaid 3 (2) 3 (4)  VA/Government 4 (2) 7 (9)  Private 90 (55) 31 (38) Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Age, median (IQR) 245 61 (54-69) 66 (57-72) <.001 Male gender, n (%) 245 76 (47) 41 (52) .62 BMI, median (IQR) 245 31 (26-34) 30 (26-33) .43 Race, n (%) 245 .32  White 138 (85) 63 (77)  Other 25 (15) 19 (20) Education, n (%) 241 <.001  Less than high school 6 (4) 13 (16)  High school diploma 78 (49) 31 (38)  Two-year college degree 42 (26) 10 (12)  Four-year college degree 21 (13) 10 (12)  Postcollege 13 (8) 17 (21) Smoking, n (%) 242 36 (22) 17 (21) .81 CAD, n (%) 245 18 (11) 8 (10) .76 Diabetes, n (%) 245 27 (17) 14 (17) .92 Depression, n (%) 245 .031  Moderate 58 (36) 41 (50)  Extreme 25 (15) 5 (6) ASA, n (%) 245 .68  1/2 75 (46) 40 (49)  3/4 88 (54) 42 (51) Employment, n (%) 245 .12  Sedentary 12 (7) 11 (13)  Light 24 (15) 8 (10)  Medium 21 (13) 5 (6)  Heavy 14 (9) 4 (5)  Unemployed/attending school 92 (56) 54 (66) Worker's Compensation, n (%) 242 3 (2) 1 (1) .72 Liability, n (%) 242 9 (6) 2 (2) .26 Insurance, n (%) 245 .045  Uninsured 2 (1) 1 (1)  Medicare 64 (40) 40 (49)  Medicaid 3 (2) 3 (4)  VA/Government 4 (2) 7 (9)  Private 90 (55) 31 (38) ASA, american society of anesthesiologists; BMI, body mass index; CAD, coronary artery disease; VA, Veteran's affairs. Bold denotes statistical significance. View Large TABLE 2. Baseline Symptoms, Diagnoses, and PRO Scores by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Symptom duration, n (%) 237 .63  Less than 3 mo 15 (9) 10 (13)  3-12 mo 67 (42) 32 (42)  More than 12 mo 79 (49) 34 (45) Motor deficit present, n (%) 245 86 (53) 49 (60) .30 Numbness present, n (%) 245 87 (53) 4 (51) .75 Independent ambulation, n (%) 245 143 (88) 65 (79) .08 Diagnosis, n (%) 245 .014  Disc herniation 25 (15) 3 (4)  Foraminal stenosis 37 (23) 16 (20)  Central stenosis 101 (62) 63 (77) Baseline PROs, median (IQR)  NDI 245 38 (28-52) 37 (20-50) .19  EQ5D 245 0.69 (0.44-0.78) 0.6 (0.47-0.78) .77  NRS-neck pain 245 6 (3-8) 5 (2-7) .16  NRS-arm pain 245 5 (2-8) 5 (2-7) .24  mJOA 241 13 (11-14) 12 (10-14) .02 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Symptom duration, n (%) 237 .63  Less than 3 mo 15 (9) 10 (13)  3-12 mo 67 (42) 32 (42)  More than 12 mo 79 (49) 34 (45) Motor deficit present, n (%) 245 86 (53) 49 (60) .30 Numbness present, n (%) 245 87 (53) 4 (51) .75 Independent ambulation, n (%) 245 143 (88) 65 (79) .08 Diagnosis, n (%) 245 .014  Disc herniation 25 (15) 3 (4)  Foraminal stenosis 37 (23) 16 (20)  Central stenosis 101 (62) 63 (77) Baseline PROs, median (IQR)  NDI 245 38 (28-52) 37 (20-50) .19  EQ5D 245 0.69 (0.44-0.78) 0.6 (0.47-0.78) .77  NRS-neck pain 245 6 (3-8) 5 (2-7) .16  NRS-arm pain 245 5 (2-8) 5 (2-7) .24  mJOA 241 13 (11-14) 12 (10-14) .02 IQR, interquartile range; NDI, neck disability index; NRS, numeric rating scale; mJOA, modified Japanese Orthopedic Association. Bold denotes statistical significance. View Large TABLE 2. Baseline Symptoms, Diagnoses, and PRO Scores by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Symptom duration, n (%) 237 .63  Less than 3 mo 15 (9) 10 (13)  3-12 mo 67 (42) 32 (42)  More than 12 mo 79 (49) 34 (45) Motor deficit present, n (%) 245 86 (53) 49 (60) .30 Numbness present, n (%) 245 87 (53) 4 (51) .75 Independent ambulation, n (%) 245 143 (88) 65 (79) .08 Diagnosis, n (%) 245 .014  Disc herniation 25 (15) 3 (4)  Foraminal stenosis 37 (23) 16 (20)  Central stenosis 101 (62) 63 (77) Baseline PROs, median (IQR)  NDI 245 38 (28-52) 37 (20-50) .19  EQ5D 245 0.69 (0.44-0.78) 0.6 (0.47-0.78) .77  NRS-neck pain 245 6 (3-8) 5 (2-7) .16  NRS-arm pain 245 5 (2-8) 5 (2-7) .24  mJOA 241 13 (11-14) 12 (10-14) .02 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Symptom duration, n (%) 237 .63  Less than 3 mo 15 (9) 10 (13)  3-12 mo 67 (42) 32 (42)  More than 12 mo 79 (49) 34 (45) Motor deficit present, n (%) 245 86 (53) 49 (60) .30 Numbness present, n (%) 245 87 (53) 4 (51) .75 Independent ambulation, n (%) 245 143 (88) 65 (79) .08 Diagnosis, n (%) 245 .014  Disc herniation 25 (15) 3 (4)  Foraminal stenosis 37 (23) 16 (20)  Central stenosis 101 (62) 63 (77) Baseline PROs, median (IQR)  NDI 245 38 (28-52) 37 (20-50) .19  EQ5D 245 0.69 (0.44-0.78) 0.6 (0.47-0.78) .77  NRS-neck pain 245 6 (3-8) 5 (2-7) .16  NRS-arm pain 245 5 (2-8) 5 (2-7) .24  mJOA 241 13 (11-14) 12 (10-14) .02 IQR, interquartile range; NDI, neck disability index; NRS, numeric rating scale; mJOA, modified Japanese Orthopedic Association. Bold denotes statistical significance. View Large Table 3 summarizes comparison of hospital LOS, complications, 90-d readmission, and 12-mo reoperation rates for anterior and posterior approach for degenerative cervical myelopathy. Patients undergoing posterior surgery had a longer median LOS by 2 d compared to those undergoing anterior surgery (3 vs 1, P < .001). Although not significant, overall complication risk was slightly higher in the anterior group (10% vs 7%, P = .52). There were no statistically significant differences in 90-d readmission (anterior-9% vs posterior-7%, P = .62) and RTW (anterior-66% vs posterior-76%, P = .34) as well as 12-mo reoperation (anterior-1% vs posterior-1%, P > .99). Patients in the posterior cohort were more likely to report worse 12-mo mJOA scores (median: 14 vs 15, P = .002). There were no significant differences in the PROs between the 2 groups (Table 4). TABLE 3. Summary of Operative Variables and Postoperative Outcomes Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Operative variables Estimated blood loss in ml, median (IQR) 221 100 (50-150) 200 (100-300) <.001 Operative time in min, median (IQR) 245 166 (125-216) 143 (112-178) .009 Number of levels, n (%) 245  3 120 (74) 29 (35) <.001  4 40 (25) 40 (49)  5 3 (2) 13 (16) Postoperative variables LOS, days, median (IQR) 245 1 (1-3) 3 (2-4) <.001 Any adverse eventa, n (%) 245 25 (15) 10 (12) .51 Any complication, n (%) 245 16 (10) 6 (7) .52 Deep venous thrombosis, n (%) 245 0 (0) 1 (1) .16 Pulmonary embolism, n (%) 245 0 (0) 1 (1) .16 Myocardial infarction, n (%) 245 0 (0) 0 (0) NA Urinary tract infection, n (%) 245 1 (1) 1 (1) .62 Surgical site infection, n (%) 245 1 (1) 1 (1) .62 Hematoma, n (%) 245 0 (0) 2 (1) .31 Dysphagia requiring nasogastric tube, n (%) 245 2 (1) 0 (0) .31 Dysphagia not requiring nasogastric tube, n (%) 245 8 (5) 1 (1) .15 Vocal cord paralysis, n (%) 245 0 (0) 0 (0) NA CSF leak, n (%) 245 0 (0) 1 (1) .16 Wound dehiscence, n (%) 245 1 (1) 1 (1) .62 CVA within 30 d, n (%) 245 0 (0) 0 (0) NA New motor deficit, n (%) 245 2 (4) 0 (0) .33 Readmission within 90 d, n (%) 245 15 (9) 6 (7) .62 RTW within 90 d, n (%) 103 49 (69) 22 (76) .34 Reoperation within 12 mo, n (%) 245 2 (1) 1 (1) >.99 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Operative variables Estimated blood loss in ml, median (IQR) 221 100 (50-150) 200 (100-300) <.001 Operative time in min, median (IQR) 245 166 (125-216) 143 (112-178) .009 Number of levels, n (%) 245  3 120 (74) 29 (35) <.001  4 40 (25) 40 (49)  5 3 (2) 13 (16) Postoperative variables LOS, days, median (IQR) 245 1 (1-3) 3 (2-4) <.001 Any adverse eventa, n (%) 245 25 (15) 10 (12) .51 Any complication, n (%) 245 16 (10) 6 (7) .52 Deep venous thrombosis, n (%) 245 0 (0) 1 (1) .16 Pulmonary embolism, n (%) 245 0 (0) 1 (1) .16 Myocardial infarction, n (%) 245 0 (0) 0 (0) NA Urinary tract infection, n (%) 245 1 (1) 1 (1) .62 Surgical site infection, n (%) 245 1 (1) 1 (1) .62 Hematoma, n (%) 245 0 (0) 2 (1) .31 Dysphagia requiring nasogastric tube, n (%) 245 2 (1) 0 (0) .31 Dysphagia not requiring nasogastric tube, n (%) 245 8 (5) 1 (1) .15 Vocal cord paralysis, n (%) 245 0 (0) 0 (0) NA CSF leak, n (%) 245 0 (0) 1 (1) .16 Wound dehiscence, n (%) 245 1 (1) 1 (1) .62 CVA within 30 d, n (%) 245 0 (0) 0 (0) NA New motor deficit, n (%) 245 2 (4) 0 (0) .33 Readmission within 90 d, n (%) 245 15 (9) 6 (7) .62 RTW within 90 d, n (%) 103 49 (69) 22 (76) .34 Reoperation within 12 mo, n (%) 245 2 (1) 1 (1) >.99 CSF, cerebrospinal fluid leak; CVA, cerebrovascular accident; NDI, neck disability index; NRS, numeric rating scale; mJOA, modified Japanese Orthopedic Association. aAdverse event is defined as the occurrence of any complication, readmission, or reoperation. Bold denotes statistical significance. View Large TABLE 3. Summary of Operative Variables and Postoperative Outcomes Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Operative variables Estimated blood loss in ml, median (IQR) 221 100 (50-150) 200 (100-300) <.001 Operative time in min, median (IQR) 245 166 (125-216) 143 (112-178) .009 Number of levels, n (%) 245  3 120 (74) 29 (35) <.001  4 40 (25) 40 (49)  5 3 (2) 13 (16) Postoperative variables LOS, days, median (IQR) 245 1 (1-3) 3 (2-4) <.001 Any adverse eventa, n (%) 245 25 (15) 10 (12) .51 Any complication, n (%) 245 16 (10) 6 (7) .52 Deep venous thrombosis, n (%) 245 0 (0) 1 (1) .16 Pulmonary embolism, n (%) 245 0 (0) 1 (1) .16 Myocardial infarction, n (%) 245 0 (0) 0 (0) NA Urinary tract infection, n (%) 245 1 (1) 1 (1) .62 Surgical site infection, n (%) 245 1 (1) 1 (1) .62 Hematoma, n (%) 245 0 (0) 2 (1) .31 Dysphagia requiring nasogastric tube, n (%) 245 2 (1) 0 (0) .31 Dysphagia not requiring nasogastric tube, n (%) 245 8 (5) 1 (1) .15 Vocal cord paralysis, n (%) 245 0 (0) 0 (0) NA CSF leak, n (%) 245 0 (0) 1 (1) .16 Wound dehiscence, n (%) 245 1 (1) 1 (1) .62 CVA within 30 d, n (%) 245 0 (0) 0 (0) NA New motor deficit, n (%) 245 2 (4) 0 (0) .33 Readmission within 90 d, n (%) 245 15 (9) 6 (7) .62 RTW within 90 d, n (%) 103 49 (69) 22 (76) .34 Reoperation within 12 mo, n (%) 245 2 (1) 1 (1) >.99 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value Operative variables Estimated blood loss in ml, median (IQR) 221 100 (50-150) 200 (100-300) <.001 Operative time in min, median (IQR) 245 166 (125-216) 143 (112-178) .009 Number of levels, n (%) 245  3 120 (74) 29 (35) <.001  4 40 (25) 40 (49)  5 3 (2) 13 (16) Postoperative variables LOS, days, median (IQR) 245 1 (1-3) 3 (2-4) <.001 Any adverse eventa, n (%) 245 25 (15) 10 (12) .51 Any complication, n (%) 245 16 (10) 6 (7) .52 Deep venous thrombosis, n (%) 245 0 (0) 1 (1) .16 Pulmonary embolism, n (%) 245 0 (0) 1 (1) .16 Myocardial infarction, n (%) 245 0 (0) 0 (0) NA Urinary tract infection, n (%) 245 1 (1) 1 (1) .62 Surgical site infection, n (%) 245 1 (1) 1 (1) .62 Hematoma, n (%) 245 0 (0) 2 (1) .31 Dysphagia requiring nasogastric tube, n (%) 245 2 (1) 0 (0) .31 Dysphagia not requiring nasogastric tube, n (%) 245 8 (5) 1 (1) .15 Vocal cord paralysis, n (%) 245 0 (0) 0 (0) NA CSF leak, n (%) 245 0 (0) 1 (1) .16 Wound dehiscence, n (%) 245 1 (1) 1 (1) .62 CVA within 30 d, n (%) 245 0 (0) 0 (0) NA New motor deficit, n (%) 245 2 (4) 0 (0) .33 Readmission within 90 d, n (%) 245 15 (9) 6 (7) .62 RTW within 90 d, n (%) 103 49 (69) 22 (76) .34 Reoperation within 12 mo, n (%) 245 2 (1) 1 (1) >.99 CSF, cerebrospinal fluid leak; CVA, cerebrovascular accident; NDI, neck disability index; NRS, numeric rating scale; mJOA, modified Japanese Orthopedic Association. aAdverse event is defined as the occurrence of any complication, readmission, or reoperation. Bold denotes statistical significance. View Large TABLE 4. Summary of 12-mo Patient-Reported Outcomes by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value NASS satisfaction 245 .70  1 98 (60) 50 (62)  2 39 (24) 15 (19)  3 15 (9) 9 (11)  4 10 (6) 7 (9) NDI, median (IQR) 245 16 (6-29) 17 (8-28) .41 EQ-5D, median (IQR) 245 0.82 (0.69-0.86) 0.78 (0.69-0.83) .25 NRS-neck pain, median (IQR) 245 2 (0-4) 2 (1-4) .31 NRS-arm pain, median (IQR) 245 1 (0-4) 0.5 (0-5) .87 mJOA, median (IQR) 253 15 (13-17) 14 (12-16) .002 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value NASS satisfaction 245 .70  1 98 (60) 50 (62)  2 39 (24) 15 (19)  3 15 (9) 9 (11)  4 10 (6) 7 (9) NDI, median (IQR) 245 16 (6-29) 17 (8-28) .41 EQ-5D, median (IQR) 245 0.82 (0.69-0.86) 0.78 (0.69-0.83) .25 NRS-neck pain, median (IQR) 245 2 (0-4) 2 (1-4) .31 NRS-arm pain, median (IQR) 245 1 (0-4) 0.5 (0-5) .87 mJOA, median (IQR) 253 15 (13-17) 14 (12-16) .002 mJOA, modified Japanese Orthopedic Association; NASS, North American Spine Society; NDI, Neck Disability Index; NRS, Numeric rating scale. Bold denotes statistical significance. View Large TABLE 4. Summary of 12-mo Patient-Reported Outcomes by Approach Variable Available data Anterior (n = 163) Posterior (n = 82) P-value NASS satisfaction 245 .70  1 98 (60) 50 (62)  2 39 (24) 15 (19)  3 15 (9) 9 (11)  4 10 (6) 7 (9) NDI, median (IQR) 245 16 (6-29) 17 (8-28) .41 EQ-5D, median (IQR) 245 0.82 (0.69-0.86) 0.78 (0.69-0.83) .25 NRS-neck pain, median (IQR) 245 2 (0-4) 2 (1-4) .31 NRS-arm pain, median (IQR) 245 1 (0-4) 0.5 (0-5) .87 mJOA, median (IQR) 253 15 (13-17) 14 (12-16) .002 Variable Available data Anterior (n = 163) Posterior (n = 82) P-value NASS satisfaction 245 .70  1 98 (60) 50 (62)  2 39 (24) 15 (19)  3 15 (9) 9 (11)  4 10 (6) 7 (9) NDI, median (IQR) 245 16 (6-29) 17 (8-28) .41 EQ-5D, median (IQR) 245 0.82 (0.69-0.86) 0.78 (0.69-0.83) .25 NRS-neck pain, median (IQR) 245 2 (0-4) 2 (1-4) .31 NRS-arm pain, median (IQR) 245 1 (0-4) 0.5 (0-5) .87 mJOA, median (IQR) 253 15 (13-17) 14 (12-16) .002 mJOA, modified Japanese Orthopedic Association; NASS, North American Spine Society; NDI, Neck Disability Index; NRS, Numeric rating scale. Bold denotes statistical significance. View Large In risk-adjusted multivariable analysis, within the limits of baseline variables included in the model, the patients undergoing anterior approach had lower odds of having higher LOS (P < .001, OR 0.16, 95% CI 0.08-0.30; Table 5). The effect of anterior vs posterior approach was not found to be significant for 90-d readmission (P = .17, OR 0.32, 95% CI 0.06-1.66), 90-d RTW (P = .07, HR 0.40, 95% CI 0.1-1.08) or 12-mo NDI (P = .36, OR 0.76, 95% CI 0.42-1.37), EQ-5D (P = .30, OR 1.36, 95% CI 0.76-2.44), NRS-neck (P = .19, OR 0.67, 95% CI 0.37-1.21) and -arm pain scores (P = .96, OR 0.99, 95% CI 0.51-1.93), mJOA scores (P = .08, OR 1.74, 95% CI 0.94-3.24), and satisfaction (P = .43, OR 1.34, 95% CI 0.64-2.85). TABLE 5. Adjusted OR (Hazard Ratio) of Approach on Outcomes Outcome OR/Hazards ratio 95% CI P-value 12m NDI 0.76 0.42 - 1.37 .36 12m EQ5D 1.36 0.76 - 2.44 .30 12m NRS-neck pain 0.67 0.37 - 1.21 .19 12m NRS-arm pain 0.99 0.51 - 1.93 .96 12m mJOA 1.74 0.94 - 3.24 .08 12m patient satisfaction 1.34 0.64 - 2.85 .43 LOS 0.16 0.08 - 0.30 <.001 90-d readmission 0.32 0.06 - 1.66 .17 RTW within 3 mo 0.40 0.16 - 1.08 .07 Outcome OR/Hazards ratio 95% CI P-value 12m NDI 0.76 0.42 - 1.37 .36 12m EQ5D 1.36 0.76 - 2.44 .30 12m NRS-neck pain 0.67 0.37 - 1.21 .19 12m NRS-arm pain 0.99 0.51 - 1.93 .96 12m mJOA 1.74 0.94 - 3.24 .08 12m patient satisfaction 1.34 0.64 - 2.85 .43 LOS 0.16 0.08 - 0.30 <.001 90-d readmission 0.32 0.06 - 1.66 .17 RTW within 3 mo 0.40 0.16 - 1.08 .07 NRS: numeric rating scale; NDI: neck disability index; mJOA: modified Japanese Orthopedic Association. Bold denotes statistical significance. View Large TABLE 5. Adjusted OR (Hazard Ratio) of Approach on Outcomes Outcome OR/Hazards ratio 95% CI P-value 12m NDI 0.76 0.42 - 1.37 .36 12m EQ5D 1.36 0.76 - 2.44 .30 12m NRS-neck pain 0.67 0.37 - 1.21 .19 12m NRS-arm pain 0.99 0.51 - 1.93 .96 12m mJOA 1.74 0.94 - 3.24 .08 12m patient satisfaction 1.34 0.64 - 2.85 .43 LOS 0.16 0.08 - 0.30 <.001 90-d readmission 0.32 0.06 - 1.66 .17 RTW within 3 mo 0.40 0.16 - 1.08 .07 Outcome OR/Hazards ratio 95% CI P-value 12m NDI 0.76 0.42 - 1.37 .36 12m EQ5D 1.36 0.76 - 2.44 .30 12m NRS-neck pain 0.67 0.37 - 1.21 .19 12m NRS-arm pain 0.99 0.51 - 1.93 .96 12m mJOA 1.74 0.94 - 3.24 .08 12m patient satisfaction 1.34 0.64 - 2.85 .43 LOS 0.16 0.08 - 0.30 <.001 90-d readmission 0.32 0.06 - 1.66 .17 RTW within 3 mo 0.40 0.16 - 1.08 .07 NRS: numeric rating scale; NDI: neck disability index; mJOA: modified Japanese Orthopedic Association. Bold denotes statistical significance. View Large DISCUSSION Decision making for the treatment of degenerative cervical myelopathy can be challenging for treating spinal surgeons, as surgical complexity, blood loss, operative time, and the incidence of complications increase significantly with the number of involved surgical segments.22,23 In this study, we performed a retrospective analysis of prospectively collected data from multiple surgical practices across the US. With over 250 patients undergoing 3to 5 level fusion surgery for degenerative cervical myelopathy and employing robust statistical methodology, our study is the largest to report postoperative and functional outcomes in this group of patients. After adjusting for a number of preoperative and operative variables, the patients undergoing ACDF with or without corpectomy had lower odds of having longer LOS compared to those undergoing posterior fusion. The 12-mo PROs, 90-d readmission and RTW were statistically similar between the groups. The literature on PROs following multilevel fusion surgery for degenerative cervical myelopathy is sparse. Similar to our analysis, the AOSpine North America cervical myelopathy study (nonrandomized, prospective study involving 278 patients from 12 US sites) demonstrated that patients with degenerative cervical myelopathy failed to detect any difference with regards to PRO scores at 12 mo between the 2 approaches.4 The authors included patients undergoing single-level as well as multilevel anterior and posterior fusion. Our analysis was focused on patients undergoing fusion at 3 to 5 levels; therefore, allowing to compare the approach in more homogenous population. Kristof and colleagues,22 in a large, single-institutional study of 103 patients, found that patients with multilevel disease treated with laminectomy and fusion compared favorably with patients treated with an anterior approach. Postoperative outcomes, including change in Nurick myelopathy scores, change in Visual Analog neck pain Scale, and satisfaction with treatment did not differ between the 2 groups at last follow-up (at least 1 yr). Finally, a recently published study by Kato and colleagues25 analyzed 435 patients enrolled in 2 international AOSpine cervical spondylotic myelopathy (CSM) studies. Following magnetic resonance imaging-based 1-to-1 propensity score matching analysis, the authors found that anterior and posterior groups did not differ significantly in terms of the postoperative mJOA score, NDI disability Index, and Short Form-36 Physical Component Summary score. In our analysis, patients undergoing a posterior approach spent on average 2 more days in the hospital, an observation that has been reported by previous prospective studies as well.5,26 This is an expected finding given the older age of the patients and the more extensive nature of the procedure, as levels of surgery and intraoperative blood loss were higher in posterior cervical fusion group. Both the anterior and posterior cervical fusions are associated with complications.27-31 A recent systematic review and meta-analysis found the complication and reoperation rates to be significantly higher in the anterior group, with the most common causes being graft nonunion and adjacent segment disease.32 In our cohort, we found that the complications including dysphagia, surgical site hematoma, and new neurological deficit were higher in anterior group, whereas pulmonary embolism, deep venous thrombosis, and cerebrospinal fluid leak were higher in the posterior group. However, there was no significant difference in overall complications, readmission, or 12-mo reoperation rate between the groups. In the study by Kato et al,25 the overall rates of perioperative complications were similar between the 2 groups (16% vs 11%); interestingly, dysphagia, and dysphonia were reported only in the anterior group, whereas surgical site infection and C5 radiculopathy were reported only in the posterior group.25 Although relatively rare, previous studies have found the anterior approaches to be relatively cost-effective compared to the posterior approaches.33,34 Specifically, Whitmore and colleagues33 analyzed 85 patients with CSM, aged 40 to 85 yr, across 7 sites. The authors investigated multiple different carotid endarterectomy methods, including Medicare cost-to-charge ratios and Medicare coding reimbursement, and consistently found ventral approaches to be more cost-effective compared to dorsal approaches (approximately $34 533).33 Similarly, Fehlings and colleagues34 analyzed 70 patients undergoing surgery for CSM at a single institution in Canada and found that the cost-utility ratio for CSM surgeries to be $32 916/ quality-adjusted life years, which is below the national benchmark to be considered highly cost-effective. Ultimately, the surgeon's familiarity and comfort with the surgical technique is a key element to be considered in decision-making. Surgeons generally prefer to treat patients with focal pathology, eg intervertebral disc herniation, using an anterior approach. Similarly, our data revealed that patients in the anterior group had a higher percentage of herniated disc than patients in the posterior group. In such cases, anterior surgery allows for better decompression of the spinal cord and improvement in myelopathy symptoms. It is important to note that arthrodesis-related variables, such as the inclusion of C7 vertebra in the multilevel constructs or development of pseudarthrosis, are not included in QOD, therefore their impact on 12-mo PROs could not be determined. Nevertheless, only 4 patients (2 in the anterior group and 2 in the posterior group) underwent revision surgery within the first 12 mo. Similarly, radiographic parameters, including T1 slope or C2-C7 lordosis, are not being captured in the spine module of QOD. These variables were included in the first version of the module; however, they were subsequently removed and are being redesigned for future versions of the spine module. Finally, given the national attention on opioid utilization and addiction, future prospective cohort studies and RCTs should incorporate postoperative opioid prescription rate as an outcome when evaluating the comparative effectiveness of different surgical approaches. Relevant variables, including opioid type, length of prescription, and dose in oral morphine milligram equivalents are currently being designed and scheduled to be released in a new, pilot version. Overall, as our knowledge on the registry's capabilities and challenges grows, there is increasing recognition of the importance of capturing a broader disease portrait with these additional data elements that can further enhance inference using real-world, observational data. Limitations This study has some limitations. First, it is a nonrandomized study and the type of surgical procedure to be performed is surgeon dependent. Given the risk for selection bias for performing one procedure over the other, future research should also focus on the factors that lead surgeons to perform anterior vs posterior surgery. A previous survey study of 91 spinal surgeons across the US showed that there is a remarkable equipoise in selection of surgical approach in patients with CSM, with the exception of C2-C7 kyphosis >5°, segmental kyphotic deformity, age over 85 yr, ossification of the posterior longitudinal ligament, and congenital canal stenosis.35 Furthermore, the results of this study should be viewed within the context of limitations of adjusting for possible confounding by indication using the baseline variables, ie there could be alternative explanations for the observed differences due to variables not included in the analysis, such as socioeconomic variables, and associated imaging findings, which may be useful in assessing patient disease severity. Second, radiographic parameters, as aforementioned, are not available in the QOD registry. As such, we could not incorporate these variables in the analysis. Nevertheless, the impact of these parameters on postoperative patient-reported outcomes has not yet been fully elucidated. According to previous work, cervical sagittal balance seems to influence only the presentation of pain and the severity of myelopathy.36 In addition, surgical treatment improved pain and mJOA scores regardless of radiographic parameters and baseline sagittal balance. Therefore, the effect of radiographic parameters on the surgical outcomes of interest remains to be determined. Third, we are limited by the 12-mo follow-up duration and the follow-up rate (71%), which is lower than the threshold of 80% that is typically set in prospective studies to ensure that the validity of findings is not threatened. However, this is not an uncommon finding in real-world registries. To address this concern, when we conducted responder/nonresponder analysis, similar patient profiles were found between the 2 groups. More importantly, this is the largest study analyzing the outcomes for patients undergoing 3 to 5 level fusion for degenerative cervical myelopathy. Fourth, given the real-world nature of our registry, standardization of the radiographic evaluations is not feasible. CONCLUSION Patients undergoing anterior approaches for 3 to 5 level degenerative cervical myelopathy had shorter hospital LOS compared to those undergoing posterior decompression and fusion. Also, patients in both groups exhibited similar long term PROs, readmission, and RTW rates. Further investigations are needed to compare the differences in longer term reoperation rates and functional outcomes before the clinical superiority of one approach over the other can be established. Disclosures A portion of this work was supported through a grant from the Neurosurgery Research and Education Foundation. The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. REFERENCES 1. Nurick S . The natural history and the results of surgical treatment of the spinal cord disorder associated with cervical spondylosis . Brain . 1972 ; 95 ( 1 ): 101 - 108 . Google Scholar CrossRef Search ADS PubMed 2. Tetreault L , Goldstein CL , Arnold P et al. Degenerative cervical myelopathy: a spectrum of related disorders affecting the aging spine . Neurosurgery . 2015 ; 77 ( suppl 4 ): S51 - S67 . Google Scholar CrossRef Search ADS PubMed 3. Boogaarts HD , Ronald H M . Prevalence of cervical spondylotic myelopathy . Eur Spine J . 2013 ; 24 ( 2 ): 139 - 141 . Google Scholar PubMed 4. Fehlings MG , Barry S , Kopjar B et al. Anterior versus posterior surgical approaches to treat cervical spondylotic myelopathy: outcomes of the prospective multicenter AOSpine North America CSM study in 264 patients . Spine . 2013 ; 38 ( 26 ): 2247 - 2252 . Google Scholar CrossRef Search ADS PubMed 5. Seng C , Tow BPB , Siddiqui MA et al. Surgically treated cervical myelopathy: a functional outcome comparison study between multilevel anterior cervical decompression fusion with instrumentation and posterior laminoplasty . Spine J . 2013 ; 13 ( 7 ): 723 - 731 . Google Scholar CrossRef Search ADS PubMed 6. Luo J , Cao K , Huang S et al. Comparison of anterior approach versus posterior approach for the treatment of multilevel cervical spondylotic myelopathy . Eur Spine J . 2015 ; 24 ( 8 ): 1621 - 1630 . Google Scholar CrossRef Search ADS PubMed 7. Lin D , Zhai W , Lian K , Kang L , Ding Z . Anterior versus posterior approach for four-level cervical spondylotic myelopathy . Orthopedics . 2013 ; 36 ( 11 ): e1431 - e1436 . Google Scholar CrossRef Search ADS PubMed 8. Zhang ZH , Yin H , Yang K et al. Anterior intervertebral disc excision and bone grafting in cervical spondylotic myelopathy . Spine . 1983 ; 8 ( 1 ): 16 - 19 . Google Scholar CrossRef Search ADS PubMed 9. Emery SE , Bolesta MJ , Banks MA , Jones PK . Robinson anterior cervical fusion comparison of the standard and modified techniques . Spine . 1994 ; 19 ( 6 ): 660 - 663 . Google Scholar CrossRef Search ADS PubMed 10. Benzel EC , Lancon J , Kesterson L , Hadden T . Cervical laminectomy and dentate ligament section for cervical spondylotic myelopathy . J Spinal Disord . 1991 ; 4 ( 3 ): 286 - 295 . Google Scholar CrossRef Search ADS PubMed 11. Carol MP , Ducker TB . Cervical spondylitic myelopathies: surgical treatment . J Spinal Disord . 1988 ; 1 ( 1 ): 59 - 65 . Google Scholar CrossRef Search ADS PubMed 12. Kaminsky SB , Clark CR , Traynelis VC . Operative treatment of cervical spondylotic myelopathy and radiculopathy. A comparison of laminectomy and laminoplasty at five year average follow-up . Iowa Orthop J . 2004 ; 24 : 95 -105. Google Scholar PubMed 13. Asher AL , Speroff T , Dittus RS et al. The National Neurosurgery Quality and Outcomes Database (N2QOD): a collaborative North American outcomes registry to advance value-based spine care . Spine . 2014 ; 39 ( 22 suppl 1 ): S106 - S116 . Google Scholar CrossRef Search ADS PubMed 14. McGirt MJ , Speroff T , Dittus RS , Harrell FE Jr , Asher AL . The national neurosurgery quality and outcomes database (N2QOD): general overview and pilot-year project description . Neurosurg Focus . 2013 ; 34 ( 1 ): 1 - 10 . 15. McGirt MJ , Bydon M , Archer KR et al. An analysis from the Quality Outcomes Database, part 1. Disability, quality of life, and pain outcomes following lumbar spine surgery: predicting likely individual patient outcomes for shared decision-making . J Neurosurg Spine . 2017 ; 27 ( 4 ): 357 - 369 . Google Scholar CrossRef Search ADS PubMed 16. Vernon H , Mior S . The Neck Disability Index: a study of reliability and validity . J Manipulative Physiol Ther . 1991 ; 14 ( 7 ): 409 - 415 . Google Scholar PubMed 17. Langley GB , Sheppeard H . The visual analogue scale: its use in pain measurement . Rheumatol Int . 1985 ; 5 ( 4 ): 145 - 148 . Google Scholar CrossRef Search ADS PubMed 18. EuroQol Group . EuroQol-a new facility for the measurement of health-related quality of life . Health Policy . 1990 ; 16 ( 3 ): 199 - 208 . CrossRef Search ADS PubMed 19. Daltroy LH , Cats-Baril WL , Katz JN , Fossel AH , Liang MH . The North American Spine Society lumbar spine outcome assessment instrument: reliability and validity tests . Spine . 1996 ; 21 ( 6 ): 741 - 748 . Google Scholar CrossRef Search ADS PubMed 20. Harrell FE Jr . Regression Modeling Strategies: With Applications to Linear Models, Logistic and Ordinal Regression, and Survival Analysis . Springer-Verlag , Cham ; 2015 . 21. R Core Team . R: A language and environment for statistical computing. R Foundation for Statistical Computing , Vienna, Austria ; 2013 . 22. Zhu B , Xu Y , Liu X , Liu Z , Dang G . Anterior approach versus posterior approach for the treatment of multilevel cervical spondylotic myelopathy: a systemic review and meta-analysis . Eur Spine J . 2013 ; 22 ( 7 ): 1583 - 1593 . Google Scholar CrossRef Search ADS PubMed 23. Komotar RJ , Mocco J , Kaiser MG . Surgical management of cervical myelopathy: indications and techniques for laminectomy and fusion . Spine J . 2006 ; 6 ( 6 ): S252 - S267 . Google Scholar CrossRef Search ADS 24. Kristof RA , Kiefer T , Thudium M et al. Comparison of ventral corpectomy and plate-screw-instrumented fusion with dorsal laminectomy and rod-screw-instrumented fusion for treatment of at least two vertebral-level spondylotic cervical myelopathy . Eur Spine J . 2009 ; 18 ( 12 ): 1951 - 1956 . Google Scholar CrossRef Search ADS PubMed 25. Kato S , Nouri A , Wu D , Nori S , Tetreault L , Fehlings MG . Comparison of anterior and posterior surgery for degenerative cervical myelopathy: an MRI-based propensity-score-matched analysis using data from the prospective multicenter AOSpine CSM North America and international studies . J Bone Joint Surg Am . 2017 ; 99 ( 12 ): 1013 - 1021 . Google Scholar CrossRef Search ADS PubMed 26. Ghogawala Z , Martin B , Benzel EC et al. Comparative effectiveness of ventral vs dorsal surgery for cervical spondylotic myelopathy . Neurosurgery . 2011 ; 68 ( 3 ): 622 - 631 . Google Scholar CrossRef Search ADS PubMed 27. Bydon M , Xu R , Macki M et al. Adjacent segment disease after anterior cervical discectomy and fusion in a large series . Neurosurgery . 2014 ; 74 ( 2 ): 139 - 146 . Google Scholar CrossRef Search ADS PubMed 28. Hosono N , Yonenobu K , Ono K . Neck and shoulder pain after laminoplasty. A noticeable complication . Spine . 1996 ; 21 ( 17 ): 1969 - 1973 . Google Scholar CrossRef Search ADS PubMed 29. Imagama S , Matsuyama Y , Yukawa Y et al. C5 palsy after cervical laminoplasty: a multicentre study . J Bone Joint Surg Br . 2010 ; 92 ( 3 ): 393 - 400 . Google Scholar CrossRef Search ADS PubMed 30. Yue W-M , Brodner W , Highland TR . Long-term results after anterior cervical discectomy and fusion with allograft and plating: a 5- to 11-year radiologic and clinical follow-up study . Spine . 2005 ; 30 ( 19 ): 2138 - 2144 . Google Scholar CrossRef Search ADS PubMed 31. Yonenobu K , Hosono N , Iwasaki M , Asano M , Ono K . Laminoplasty versus subtotal corpectomy. A comparative study of results in multisegmental cervical spondylotic myelopathy . Spine . 1992 ; 17 ( 11 ): 1281 - 1284 . Google Scholar CrossRef Search ADS PubMed 32. Zhu B , Xu Y , Liu X , Liu Z , Dang G . Anterior approach versus posterior approach for the treatment of multilevel cervical spondylotic myelopathy: a systemic review and meta-analysis . Eur Spine J . 2013 ; 22 ( 7 ): 1583 - 1593 . Google Scholar CrossRef Search ADS PubMed 33. Whitmore RG , Schwartz JS , Simmons S , Stein SC , Ghogawala Z . Performing a cost analysis in spine outcomes research: comparing ventral and dorsal approaches for cervical spondylotic myelopathy . Neurosurgery . 2012 ; 70 ( 4 ): 860 - 867 . Google Scholar CrossRef Search ADS PubMed 34. Fehlings MG , Jha NK , Hewson SM , Massicotte EM , Kopjar B , Kalsi-Ryan S . Is surgery for cervical spondylotic myelopathy cost-effective? A cost-utility analysis based on data from the AOSpine North America prospective CSM study . J Neurosurg Spine . 2012 ; 17 ( 1 suppl ): 89 - 93 . Google Scholar CrossRef Search ADS PubMed 35. Ghogawala Z , Coumans J-V , Benzel EC , Stabile LM , Barker FG , Ventral versus dorsal decompression for cervical spondylotic myelopathy: surgeons? Assessment of eligibility for randomization in a proposed randomized controlled trial: results of a survey of the Cervical Spine Research Society . Spine . 2007 ; 32 ( 4 ): 429 - 436 . Google Scholar CrossRef Search ADS PubMed 36. Nicholson K , Millhouse PW , Pflug E et al. Outcomes of treatment for cervical myelopathy . Spine J . 2016 ; 16 ( 10 ): S113 - S114 . Google Scholar CrossRef Search ADS Supplemental digital content is available for this article at www.operativeneurneuros-online.com. Supplemental Digital Content. Table. Comparison of demographics and clinical characteristics between responders and non-responders COMMENTS Degenerative cervical myelopathy (DCM) is a common condition in the elderly. In today's society, with demographic data reflecting the growing senior population, prompt diagnosis and treatment is crucial for this condition. Current operative treatment for DCM includes mainly anterior cervical discectomy or corpectomy and fusion (ACDF or ACCF) and posterior spinal decompression and fusion (PSF). The authors of this article aimed to compare anterior versus posterior surgery in terms of outcome for 3–5 level DCM. The authors conduct a well-organized analysis of a multicenter, prospectively collected dataset examining a very relevant topic that remains controversial in the field of spine surgery today. While controversial, it is generally accepted that ACDF is preferable for focal disease while PSF is used when multilevel long fusion construct is required. The intermediate levels are where controversies exist. Using the Quality Outcomes Database (QOD), the authors of this article reported their assessment of postoperative functional outcome related to surgical approach for DCM. They demonstrated an advantage of reduced length of stay (LOS) with the anterior procedure for 3 to 5 levels fusion. However, 90-day readmission, 12-month NDI, EQ-5D, NRS-neck, arm pain, mJOA, overall complications, return to work, and patient satisfaction were not significantly different between groups. Furthermore, the authors showed that although overall complication rate between the 2 groups were similar, the types of complications were specific to either the anterior or posterior approach. Finally, we applaud the authors on their contribution to our understanding of DCM. Currently there are some generally accepted indications for anterior surgery including ventral pathology, focal disease, and presence of kyphotic deformity. Conversely, the presence of posterior pathology, ossification of the posterior longitudinal ligament, and multilevel stenosis usually favors a decompression and fusion through a posterior approach.1 Previously, the outcome of anterior versus posterior surgery had been shown to be equivalent in a multicenter, prospective observational study by Fehlings et al 2013.2 Hence, there is still no definitive answer as to the best surgical approach for DCM. Surgical decision making is still largely based on surgeon preference, individual experience, and technical comfort. Thus, we believe with ongoing research in this field, we will continue to resolve the controversies and improve our knowledge in the area of DCM. Fan Jiang Michael G. Fehlings Toronto, Canada 1. Wilson JR , Tetreault LA , Kim J et al. State of the Art in Degenerative Cervical Myelopathy: An Update on Current Clinical Evidence . Neurosurgery 2017 ; 80 : S33 - S45 . Google Scholar CrossRef Search ADS PubMed 2. Fehlings MG , Barry S , Kopjar B et al. Anterior versus posterior surgical approaches to treat cervical spondylotic myelopathy: outcomes of the prospective multicenter AOSpine North America CSM study in 264 patients . Spine (Phila Pa 1976) 2013 ; 38 : 2247 - 52 . Copyright © 2018 by the Congress of Neurological Surgeons This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

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NeurosurgeryOxford University Press

Published: May 8, 2018

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