Effects of physical activity goal attainment on engagement and outcomes in the National Diabetes Prevention Program

Effects of physical activity goal attainment on engagement and outcomes in the National Diabetes... Abstract The National Diabetes Prevention Program (NDPP) is the most widely available behavioral intervention to prevent diabetes, but attrition is a concern and strategies are needed to make the program more engaging. Previous evidence suggests that the 150-min weekly physical activity goal in NDPP is hard for many to achieve. Further study of the impact of this protocol recommendation may improve understanding for NDPP reach and effectiveness in reducing diabetes risk. We conducted an observational study of relationships between physical activity goal attainment and retention and weight loss among 391 NDPP participants between March 2013 and May 2016. Average percent of self-reported weekly physical activity goal attainment was 52.7% (SD = 35.1). Goal attainment was related to percent of sessions attended, β = 0.21 (p < .01) and program completion (OR 0.47; p < .05; 95% CI 0.24–0.90). Each occurrence of goal failure was associated with a 25% lower likelihood of attending the next session (OR 0.75; p < .001; 95% CI 0.64–0.87). Goal attainment was also related to total percent weight loss, β = −0.14 (p < .05) and achieving ≥5% weight loss (OR 0.39; p < .01; 95% CI 0.19–0.76), but there was no effect of goal attainment on weight change per session attended. Failing to attain physical activity goals may deter retention in the NDPP. Yet, goal attainment did not affect the rate of weight loss per session attended. It may be important to encourage continued engagement among individuals who struggle to achieve physical activity goals. Moreover, it may be necessary to modify physical activity recommendations to meet individual needs. Implications Practice: High attrition is one of the largest barriers to successful dissemination of the National Diabetes Prevention Program (NDPP), and program requirements to obtain at least 150 min of weekly physical activity may be a contributing factor to poor engagement. Policy: If findings are replicable, it may be important to modify the Centers for Disease Control and Prevention’s NDPP curriculum to present physical activity goals in a patient-centered manner. Research: Future research is needed to determine whether NDPP participants would be more likely to complete the program, and thus lose more weight and better prevent diabetes, if physical activity goals were presented in a patient-centered manner. INTRODUCTION Type 2 diabetes affects 9.3% of U.S. adults [1], leading to tremendous public health and economic burden [2]. Diabetes affects racial/ethnic minority populations at disproportionately high rates [1]. The National Diabetes Prevention Program (NDPP) is the most widely available behavioral intervention to prevent diabetes [3], which is a translation of a highly successful clinical trial of intensive lifestyle support for weight loss that reduced incidence by 58% [4]. Greater engagement in the NDPP appears to yield better outcomes, but high attrition rates have been a concern [5, 6]. Retention is challenging for some racial/ethnic populations in the NDPP [6, 7]. Although resolving logistical barriers to attendance may help, such as providing childcare or transportation, a major need is to identify strategies to make the NDPP more engaging. We aimed to explore preliminary evidence for program modifications that may improve translation of the NDPP, while not detracting from its efficacy. The NDPP curriculum is published by the Centers for Disease Control and Prevention (CDC), and the most recent version was released in March 2016 [3]. To achieve weight loss the curriculum presents a goal of obtaining 150 or more minutes of weekly moderate to vigorous physical activity, a recommendation for which there has been strong evidence and national guidelines. The 2008 Physical Activity Guidelines for Americans include recommendations for at least 150 minutes of moderately intense physical activity [8]. The majority (67%) of participants in the original clinical trial of the NDPP successfully met or exceeded this physical activity goal [9]. Although physical activity was not found to be an independent predictor of diabetes incidence, participants who attained the physical activity goal without meeting the weight loss goal had a 44% reduction in incidence [10]. Yet, attaining 150 weekly minutes of physical activity appears more challenging in the NDPP than in the original clinical trial, especially for racial/ethnic minorities. A recent CDC report showed that across nationwide implementation of the NDPP, only 42% of participants met the physical activity goal, with lower attainment among participants representing racial/ethnic minorities [6]. Whether attainment of physical activity goals affects engagement in the NDPP is unknown, and merits exploration to inform future translations. We assessed effects of physical activity goal attainment on engagement and weight loss in an implementation site of the NDPP serving a large, diverse at-risk population. We predicted that black and Latino participants would have lower rates of physical activity goal attainment than nonHispanic whites. Our primary hypothesis was that participants who were less able to meet weekly physical activity goals would be more likely to drop out of the NDPP and lose less weight than participants who reported greater success. Methods We implemented the yearlong NDPP at a large safety net healthcare system serving the Denver, Colorado metro region following CDC-standardized guidelines [3]. We conducted an observational study of relationships between physical activity goal attainment and retention and weight loss in the program between March 2013 and May 2016. The Colorado Multiple Institutional Review Board approved the protocol for program evaluation. Eligibility criteria English- and Spanish-speaking adults at risk for diabetes were eligible to participate in the NDPP. Diabetes risks included a body mass index (BMI) of ≥24 (or ≥22 if Asian) and a history of recent prediabetes or gestational diabetes mellitus [11]. Prediabetes was based on a laboratory test within the past year indicating a fasting blood glucose of 100 to 125, blood glucose of 140 to 199 measured 2 hr after a 75 gm glucose load, or a hemoglobin A1c of 5.7 to 6.4. Gestational diabetes was based on a past diagnosis. Patients were also eligible based on a diabetes risk questionnaire [12]. Participants were excluded if they were pregnant at enrollment or known to have diabetes. Recruitment We identified and recruited participants through provider referrals, flyers, word of mouth, and a risk registry based on electronic medical records. Further details of our recruitment strategies have been published previously [13]. There were no costs to participate in the NDPP per grant-funding and institutional support. There were no incentives to attend or complete the program. To reduce barriers to initial engagement, participants were encouraged to attend at least one session, even if they were unable to commit upfront to a full year of NDPP classes. Eight hundred sixty-five participants attended at least one session from March 2013 to May 2016. NDPP implementation We used the 2012 NDPP curriculum with 16 weekly to biweekly sessions, followed by at least six monthly sessions over a total duration of 1 year [3]. Due to scheduling adjustments, participants who began the program in March 2013 were offered 24 NDPP sessions, while participants who began at later dates had the opportunity to participate in 22 sessions. Bilingual lay health educators completed CDC-approved training and conducted NDPP classes. Make-up sessions were provided as needed. Individuals were encouraged to lose seven percent of their body weight through diet and physical activity across the yearlong program, with an overall program goal of at least 5% average weight loss among participants. Weight was measured at each session, although the NDPP does not prescribe a weekly weight loss goal. Following the NDPP curriculum, the weekly physical activity goal of 150 min or more of moderate to vigorous intensity was introduced in the fifth session. The curriculum recommends beginning physical activity gradually as needed (e.g., “Work up to the 150-min goal slowly. It may take about 4 weeks to do so.”) Participants were instructed to track start and stop times and report their total weekly minutes of physical activity at the following session. As such, physical activity was reported at the sixth and all subsequent sessions. Although the NDPP curriculum was revised in 2016, there were no major changes in physical activity instruction from the 2012 version. Participants were also encouraged to eat 25% or less of calories from fat, but dietary adherence was not recorded and is no longer a program goal in the revised curriculum. Thus, we focused this evaluation on physical activity as the only frequently prescribed and monitored behavioral goal in the NDPP. Study sample To focus on effects of physical activity goal attainment, for this analysis we included 406 participants (46.9% of the overall sample) who attended the NDPP after physical activity was first reported in the sixth session given physical activity was not yet monitored in sessions 1–5. We further excluded 15 participants who did not report physical activity for a final sample of 391 participants. Measures Demographic and baseline health characteristics included race/ethnicity, language, age, gender, and baseline BMI and hemoglobin A1c, which were extracted from electronic health records. Physical activity was assessed as self-reported minutes of moderate to vigorous activity completed in the previous week. We operationalized physical activity goal attainment as the percentage of times in which participants reported meeting or exceeding weekly physical activity goals compared to the total number of times in which they reported activity. For example, a participant who reported achieving ≥150 min of physical activity for four of 10 weeks was assigned a goal achievement percentage of 40%. As participants may have begun physical activity gradually in the first four weeks per curriculum guidance, we further assessed goal attainment for sessions 6–9 versus 10+ to inform whether goal attainment across the NDPP was an appropriate measure for hypothesis testing. We assessed the total percent of NDPP sessions attended. We also evaluated the percent of participants who completed the program. Per CDC standards, completion was defined as attending at least nine classes in the first 6 months, plus three or more sessions attended in months 7 through 12 [11]. Baseline weight was defined as a participant’s weight at their first session attended. Final weight was based on the last session each participant attended. We calculated the (a) average percent weight change per session attended, (b) total percent weight change from a participant’s baseline weight to their final session attended, and (c) proportion of participants who achieved at least 5% weight loss. Although the NDPP’s objective is diabetes prevention, weight loss is the primary outcome and glucose or A1c outcomes are not measured. Analysis Differences in characteristics between the study sample and excluded individuals who dropped out prior to introduction of physical activity goals were assessed using t-tests and chi-square tests. We then assessed descriptive statistics for sociodemographic and baseline health characteristics, physical activity, attendance, and weight loss outcomes. We used t-tests and linear regression to examine sociodemographic differences in rates of attaining physical activity goals. We focused our analysis on goal attainment rather than the total amount of physical activity to assess the impact of goal attainment versus failure on engagement. We compared rates of goal attainment in early versus later sessions using a paired t-test. We used multivariate linear and logistic regression to determine associations of physical activity goal attainment on attendance and weight change. Covariates included age, gender, race/ethnicity, baseline BMI, and baseline hemoglobin A1c, which were previously found to predict differences in physical activity levels among participants in the original clinical trial [14]. Finally, we used logistic regression in a post hoc analysis to determine whether participants who reported failing to achieve physical activity goals at one session were less likely to attend the next scheduled session. SPSS version 21 was used for all analyses. RESULTS Descriptive results Characteristics of the study sample are presented in Table 1. Participants had a mean age of 51.9 (SD = 12.6) and tended to be female (n = 298; 77.0%). Over half of participants were of Latino ethnicity (n = 200; 53.9%), whereas 23.2% were nonHispanic Black (n = 86), and 21.8% were nonHispanic White (n = 81). The average BMI at program entry was 34.6 (SD = 7.5). Mean hemoglobin A1c at program entry was 6.0 (SD = 0.5). Of participants who started the NDPP, comparably fewer Latinos continued to session six and beyond when physical activity was measured (p < .05); in contrast, relatively more African American participants continued in the program (p < .05). No other characteristics significantly differed between the study sample and excluded individuals. Table 1 Participant characteristics and outcomes in the national diabetes prevention program (N = 391)a Variable n (%) or M (SD) Age 51.9 (12.6) Female gender 298 (77.0) Race/Ethnicity  Latino 200 (53.9)  Black 86 (23.2)  White 81 (21.8)  Other/unknown 24 (6.1) Baseline body mass index 34.6 (7.5) Baseline hemoglobin A1c 6.0 (0.5) Weekly minutes of physical activity 198.4 (139.7) Percent weekly physical activity goal attainment 52.7 (35.1) Percent of sessions attended 65.8 (24.2) Average percent weight loss per session attended 0.22 (0.37) Percent weight loss 3.4 (5.8) Obtained ≥5% weight loss 132 (33.8) Variable n (%) or M (SD) Age 51.9 (12.6) Female gender 298 (77.0) Race/Ethnicity  Latino 200 (53.9)  Black 86 (23.2)  White 81 (21.8)  Other/unknown 24 (6.1) Baseline body mass index 34.6 (7.5) Baseline hemoglobin A1c 6.0 (0.5) Weekly minutes of physical activity 198.4 (139.7) Percent weekly physical activity goal attainment 52.7 (35.1) Percent of sessions attended 65.8 (24.2) Average percent weight loss per session attended 0.22 (0.37) Percent weight loss 3.4 (5.8) Obtained ≥5% weight loss 132 (33.8) aData are presented as mean (standard deviation) and frequency (%). View Large Table 1 Participant characteristics and outcomes in the national diabetes prevention program (N = 391)a Variable n (%) or M (SD) Age 51.9 (12.6) Female gender 298 (77.0) Race/Ethnicity  Latino 200 (53.9)  Black 86 (23.2)  White 81 (21.8)  Other/unknown 24 (6.1) Baseline body mass index 34.6 (7.5) Baseline hemoglobin A1c 6.0 (0.5) Weekly minutes of physical activity 198.4 (139.7) Percent weekly physical activity goal attainment 52.7 (35.1) Percent of sessions attended 65.8 (24.2) Average percent weight loss per session attended 0.22 (0.37) Percent weight loss 3.4 (5.8) Obtained ≥5% weight loss 132 (33.8) Variable n (%) or M (SD) Age 51.9 (12.6) Female gender 298 (77.0) Race/Ethnicity  Latino 200 (53.9)  Black 86 (23.2)  White 81 (21.8)  Other/unknown 24 (6.1) Baseline body mass index 34.6 (7.5) Baseline hemoglobin A1c 6.0 (0.5) Weekly minutes of physical activity 198.4 (139.7) Percent weekly physical activity goal attainment 52.7 (35.1) Percent of sessions attended 65.8 (24.2) Average percent weight loss per session attended 0.22 (0.37) Percent weight loss 3.4 (5.8) Obtained ≥5% weight loss 132 (33.8) aData are presented as mean (standard deviation) and frequency (%). View Large The average percentage of success attaining weekly physical activity goals across the duration of the yearlong program was 52.7% (SD = 35.1), meaning participants reported meeting or exceeding physical activity goals about half of the time on average. There was no significant difference in rates of goal attainment between early versus later sessions: 52.8% (SD = 43.0) and 54.6% (SD = 35.6), respectively, p = 0.598. Only 17.9% of participants (n = 70) fully met or exceeded weekly physical activity goals on all occasions. Men had higher rates of attaining weekly physical activity goals than women, 61.7% (SD = 35.7) versus 49.8% (SD = 34.4), respectively, p < .01. Percent of physical activity goal attainment among Latino and black participants were 51.2% (SD = 34.5) and 53.5% (SD = 33.4), respectively, while percent goal attainment among white participants was 58.3% (SD = 36.6). In contrast to our hypothesized prediction, these differences were not statistically significant. There were also no significant differences in achieving physical activity goals by age, baseline BMI, or baseline A1c. Average reported weekly physical activity was 198.4 min (SD = 139.7) across all participants. Although average physical activity for the overall sample exceeded 150 weekly minutes, examining results by a median split of percent goal attainment (median = 53.8%) indicated high variability between groups. Participants above the median (high goal attainment group) reported 286.6 average weekly minutes of physical activity (SD = 142.5); those below the median (low goal attainment group) reported 109.7 min (SD = 55.4) on average. Participants attended 65.8% (SD = 24.2) of all NDPP sessions on average. Mean attendance was 15.6 (65.0%) sessions (SD = 5.8) among 97 participants who were offered 24 sessions. For 294 participants who were offered up to 22 sessions, average attendance was 14.5 (65.9%) sessions (SD = 5.3). Of the participants, 39% (n = 152) fully completed the yearlong program per CDC standards. Mean weight loss was 3.4% (SD = 5.8). The average rate of weight loss per session attended was 0.22% (SD = 0.37). Approximately one third (33.8%) of participants (n = 132) achieved at least 5% weight loss. Regression results Table 2 presents a summary of multiple linear and logistic regression analyses for effects of physical activity goal attainment on attendance and weight loss in the NDPP. Supporting our primary hypothesis, there was a linear relationship between physical activity goal attainment and percent of sessions attended, β = 0.21 (p < .01). For each 10% decrease in physical activity goal attainment, participants had a 5.3% lower likelihood of completing the program (OR 0.47; p < .05; 95% CI 0.24–0.90). Each occurrence of not attaining the physical activity goal of 150 min/week predicted a 25% lower likelihood of attending the next scheduled session (OR 0.75; p < .001; 95% CI 0.64–0.87). This within-subjects analysis was intended to further assess a possible causal relationship between goal attainment and engagement. There was also a linear relationship between physical activity goal attainment and total percent weight loss, β = −0.14 (p < .05). There was no significant relationship between physical activity goal attainment and weight change per session attended. For every 10% decrease in physical activity goal attainment, participants had a 6.1% lower likelihood of achieving at least five percent weight loss (OR 0.39; p < .01; 95% CI 0.19–0.76). Table 2 Summary of multiple linear and logistic regression analyses for attendance and weight loss by physical activity goal attainment (N = 391)a B SE(B) β t p value Percent of sessions attended** 0.14 0.04 0.21 3.18 .002 Percent of weight change by session attended −0.08 0.06 −0.07 −1.30 .194 Total percent weight change* −2.26 0.93 −0.14 −2.43 .016 Exp(B) 95% CI p value Completed program* 0.76 0.34 0.47 0.24–0.90 .024 Obtained ≥5% weight loss** 0.94 0.36 0.39 0.19–0.76 .008 B SE(B) β t p value Percent of sessions attended** 0.14 0.04 0.21 3.18 .002 Percent of weight change by session attended −0.08 0.06 −0.07 −1.30 .194 Total percent weight change* −2.26 0.93 −0.14 −2.43 .016 Exp(B) 95% CI p value Completed program* 0.76 0.34 0.47 0.24–0.90 .024 Obtained ≥5% weight loss** 0.94 0.36 0.39 0.19–0.76 .008 aModels were adjusted for age, gender, race/ethnicity, baseline body mass index, and baseline A1c. *p < .05; **p < .01. View Large Table 2 Summary of multiple linear and logistic regression analyses for attendance and weight loss by physical activity goal attainment (N = 391)a B SE(B) β t p value Percent of sessions attended** 0.14 0.04 0.21 3.18 .002 Percent of weight change by session attended −0.08 0.06 −0.07 −1.30 .194 Total percent weight change* −2.26 0.93 −0.14 −2.43 .016 Exp(B) 95% CI p value Completed program* 0.76 0.34 0.47 0.24–0.90 .024 Obtained ≥5% weight loss** 0.94 0.36 0.39 0.19–0.76 .008 B SE(B) β t p value Percent of sessions attended** 0.14 0.04 0.21 3.18 .002 Percent of weight change by session attended −0.08 0.06 −0.07 −1.30 .194 Total percent weight change* −2.26 0.93 −0.14 −2.43 .016 Exp(B) 95% CI p value Completed program* 0.76 0.34 0.47 0.24–0.90 .024 Obtained ≥5% weight loss** 0.94 0.36 0.39 0.19–0.76 .008 aModels were adjusted for age, gender, race/ethnicity, baseline body mass index, and baseline A1c. *p < .05; **p < .01. View Large DISCUSSION This study explored possible effects of physical activity goal attainment on engagement and outcomes in an intervention to prevent diabetes, which has not been reported on previously to our knowledge. We found that approximately half of NDPP participants achieved the goal of 150 weekly minutes of physical activity, compared to about two thirds of participants in the original trial [9]. Women were less likely to attain physical activity goals than men, although more women than men enrolled in the NDPP, consistent with national dissemination results [6]. Although Latino and black participants reported lower levels of goal attainment than white participants, racial/ethnic differences in physical activity goal attainment were not statistically significant. Notably, findings suggest that the extent to which participants met physical activity goals did not affect rates of weight loss per session attended. Yet, less success achieving physical activity goals was associated with less participation and less total weight loss in the NDPP, which supported our primary hypothesis. Difficulty achieving physical activity goals is consistent with previous findings that many participants in the original clinical trial on which the NDPP is based were unable to attain physical activity goals [9], and that women with diabetes risks are less active than men [6, 14]. Although previous literature has shown racial/ethnic differences in physical activity levels [6, 14], trends reported here were not significant. To reduce diabetes incidence, it may be important to encourage continued engagement among individuals who struggle to achieve 150 weekly minutes of physical activity, including women. Moreover, it may be beneficial to place greater emphasis on setting personalized physical activity goals throughout the NDPP to address the needs and capabilities of each participant. This is consistent with a systematic review of necessary intervention components for diabetes prevention that found evidence supporting motivational interviewing motivational interviewing and individualized tailoring of recommendations, rather than prescriptive guidance [15]. At the same time, it remains critical to support participants in working toward achieving evidence-based guidelines for physical activity, which is important for reducing both diabetes risk [10] and all-cause mortality [16]. Higher exercise self-efficacy and readiness for change, and lower anxiety, depression, and stress were found to predict physical activity in the seminal diabetes prevention study [17], so it may also be important to assess and address these factors in future diabetes prevention efforts. Limitations Results are not fully generalizable as this was a quality improvement program with an observational study design. We conducted the NDPP in a safety net healthcare system where many patients are low-income and have government insurance, so they may have had fewer resources with which to engage in physical activity than the general population. Physical activity was based on self-report. Several analyses were correlational in nature due to the simultaneous assessment of physical activity, engagement, and weight loss. Nonetheless, findings from the post hoc analysis further supported the possibility of a causal relationship between failing to achieve physical activity goals at one session and a lower likelihood of attending the next scheduled session. We were unable to account for possible alternative explanations. We did not assess motivation to engage in the NDPP, which could underlie the relationship between physical activity goal attainment and participation. We also did not systematically assess perceived barriers to physical activity and participation in the NDPP. Participants may have been unable to complete the program for the same reasons that they had challenges attaining physical activity goals, such as due to caregiving responsibilities. Participants may also have self-selected personal goals of less than 150 weekly activity minutes, which could alter perceptions of and responses to goal attainment. Finally, participants who attended a greater number of sessions had more opportunities to report physical activity than those who attended fewer sessions. Yet, we could not control for attendance as reporting activity was dependent on participants coming to sessions. We sought to capture the relative experience of goal success versus failure regardless of the number of sessions attended by using percentage of weekly physical activity goal attainment as the primary predictor. Future research Further evidence is needed to confirm the effects of physical activity goal attainment on engagement and outcomes in the NDPP, including glucose and/or A1c as direct indicators of diabetes risks. Suggestions for more rigorous research include conducting an experiment in which participants are randomized to receive guidance using similar prescriptive recommendations for physical activity as compared to a patient-centered approach in which participants are encouraged to “do the best that you can.” Suggested future qualitative research includes interviewing participants to see if they identify prescriptive physical activity goals as problematic, as well as what other factors contribute to drop out. Efforts are needed to determine what modifications are needed to support risk reduction behaviors among women with diabetes risks. Although we did not find significant racial/ethnic differences in physical activity goal attainment, previous research and trends reported here suggest further research may also be needed to determine culturally appropriate messages for setting physical activity goals. Conclusion Preliminary evidence from this observational study suggests that failing to attain physical activity goals may be a deterrent to persistence in the NDPP. At the same time, the extent to which participants achieved 150 weekly minutes of physical activity did not affect NDPP efficacy in terms of the rate of weight loss per session attended. The key question these findings raise is whether participants who fail to achieve physical activity goals would be more likely to stay in the program longer, and thus lose more weight and better prevent diabetes, if the NDPP curriculum was modified to present goals in a more patient-centered manner. This relationship needs further attention to support development of improved diabetes prevention strategies. Acknowledgments The findings and manuscript have been submitted solely to TBM and have not been previously published or posted online. A poster of this work was presented on March 30, 2017 at the Society for Behavioral Medicine annual meeting. The authors have full control of all primary data and we agree to allow the journal to review our data if requested. This work was funded by the Amendment 35 Cancer, Cardiovascular Disease and Pulmonary Disease Grant Program administered by the Colorado Department of Public Health and Environment, as well as an award from America’s Health Insurance Plans in partnership with the Centers for Disease Control and Prevention. Denver Health and Hospital Authority provided additional financial support. The contents of this publication are solely the responsibility of the authors and do not represent official views of these organizations. The Colorado Multiple Institutional Review Board approved the protocol for program evaluation (i.e., nonhuman subject research). As such, informed consent requirements were waived. No animals were involved. Compliance with Ethical Standards Conflict of interest: Natalie D. Ritchie, Jennifer K. Carroll, Jodi Summers Holtrop, and Edward P. Havranek have no conflict of interest to report. References 1. Centers for Disease Control and Prevention (CDC) . National Diabetes Statistics Report: Estimates of Diabetes and its Burden in the United States, 2014 . Atlanta, GA : CDC, US Department of Health and Human Services ; 2014 . 2. American Diabetes Association . Economic costs of diabetes in the US in 2012 . Diabetes Care . 2013 ; 36 ( 4 ): 1033 – 1046 . Crossref Search ADS PubMed 3. CDC . National Diabetes Prevention Program ; 2016 . Available at https://www.cdc.gov/diabetes/prevention/lifestyle-program/curriculum.html. Accessibility verified March 7, 2017 . 4. Knowler WC , Barrett-Connor E , Fowler SE , et al. ; Diabetes Prevention Program Research Group . Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin . N Engl J Med . 2002 ; 346 ( 6 ): 393 – 403 . Google Scholar Crossref Search ADS PubMed 5. Ali MK , Echouffo-Tcheugui J , Williamson DF . How effective were lifestyle interventions in real-world settings that were modeled on the Diabetes Prevention Program ? Health Aff (Millwood) . 2012 ; 31 ( 1 ): 67 – 75 . Google Scholar Crossref Search ADS PubMed 6. Ely EK , Gruss SM , Luman ET , Albright AL . Response to comment on Ely et al. A national effort to prevent type 2 diabetes: Participant-level evaluation of CDC’s National Diabetes Prevention Program. Diabetes Care 2017; 40:1331-1341 . Diabetes Care . 2017 ; 40 ( 11 ): e163 . Google Scholar Crossref Search ADS PubMed 7. Ritchie ND , Christoe-Frazier L , McFann KK , Havranek EP , Pereira RI . Effect of the national diabetes prevention program on weight loss for English- and Spanish-speaking Latinos . Am J Health Promot . 2017 . doi: 10.1177/0890117117698623 . 8. Physical Activity Guidelines Advisory Committee . Physical activity guidelines for Americans . Washington, DC : US Department of Health and Human Services ; 2008 : 15 – 34 . 9. Wing RR , Hamman RF , Bray GA , et al. ; Diabetes Prevention Program Research Group . Achieving weight and activity goals among diabetes prevention program lifestyle participants . Obes Res . 2004 ; 12 ( 9 ): 1426 – 1434 . Google Scholar Crossref Search ADS PubMed 10. Hamman RF , Wing RR , Edelstein SL , et al. Effect of weight loss with lifestyle intervention on risk of diabetes . Diabetes Care . 2006 ; 29 ( 9 ): 2102 – 2107 . Google Scholar Crossref Search ADS PubMed 11. CDC . CDC Diabetes Prevention Recognition Program Standards and Operating Procedures ; 2015 . Available at http://www.cdc.gov/diabetes/prevention/pdf/dprp-standards.pdf. Accessibility verified November 7, 2016 . 12. CDC . CDC Prediabetes Screening Test . Available at http://www.cdc.gov/diabetes/prevention/pdf/prediabetestest.pdf. Accessibility verified February 13, 2017 . 13. Ritchie N , Swigert T . Establishing an effective primary care provider referral network for the National Diabetes Prevention Program . AADE in Practice . 2016 ; 4 ( 4 ): 20 – 25 . Google Scholar Crossref Search ADS 14. Kriska AM , Edelstein SL , Hamman RF , et al. Physical activity in individuals at risk for diabetes: Diabetes Prevention Program . Med Sci Sports Exerc . 2006 ; 38 ( 5 ): 826 – 832 . Google Scholar Crossref Search ADS PubMed 15. Greaves CJ , Sheppard KE , Abraham C , et al. ; IMAGE Study Group . Systematic review of reviews of intervention components associated with increased effectiveness in dietary and physical activity interventions . BMC Public Health . 2011 ; 11 : 119 . Google Scholar Crossref Search ADS PubMed 16. Schmid D , Ricci C , Leitzmann MF . Associations of objectively assessed physical activity and sedentary time with all-cause mortality in US adults: the NHANES study . PLoS One . 2015 ; 10 ( 3 ): e0119591 . Google Scholar Crossref Search ADS PubMed 17. Delahanty LM , Conroy MB , Nathan DM ; Diabetes Prevention Program Research Group . Psychological predictors of physical activity in the diabetes prevention program . J Am Diet Assoc . 2006 ; 106 ( 5 ): 698 – 705 . Google Scholar Crossref Search ADS PubMed © Society of Behavioral Medicine 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Translational Behavioral Medicine Oxford University Press

Effects of physical activity goal attainment on engagement and outcomes in the National Diabetes Prevention Program

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Abstract

Abstract The National Diabetes Prevention Program (NDPP) is the most widely available behavioral intervention to prevent diabetes, but attrition is a concern and strategies are needed to make the program more engaging. Previous evidence suggests that the 150-min weekly physical activity goal in NDPP is hard for many to achieve. Further study of the impact of this protocol recommendation may improve understanding for NDPP reach and effectiveness in reducing diabetes risk. We conducted an observational study of relationships between physical activity goal attainment and retention and weight loss among 391 NDPP participants between March 2013 and May 2016. Average percent of self-reported weekly physical activity goal attainment was 52.7% (SD = 35.1). Goal attainment was related to percent of sessions attended, β = 0.21 (p < .01) and program completion (OR 0.47; p < .05; 95% CI 0.24–0.90). Each occurrence of goal failure was associated with a 25% lower likelihood of attending the next session (OR 0.75; p < .001; 95% CI 0.64–0.87). Goal attainment was also related to total percent weight loss, β = −0.14 (p < .05) and achieving ≥5% weight loss (OR 0.39; p < .01; 95% CI 0.19–0.76), but there was no effect of goal attainment on weight change per session attended. Failing to attain physical activity goals may deter retention in the NDPP. Yet, goal attainment did not affect the rate of weight loss per session attended. It may be important to encourage continued engagement among individuals who struggle to achieve physical activity goals. Moreover, it may be necessary to modify physical activity recommendations to meet individual needs. Implications Practice: High attrition is one of the largest barriers to successful dissemination of the National Diabetes Prevention Program (NDPP), and program requirements to obtain at least 150 min of weekly physical activity may be a contributing factor to poor engagement. Policy: If findings are replicable, it may be important to modify the Centers for Disease Control and Prevention’s NDPP curriculum to present physical activity goals in a patient-centered manner. Research: Future research is needed to determine whether NDPP participants would be more likely to complete the program, and thus lose more weight and better prevent diabetes, if physical activity goals were presented in a patient-centered manner. INTRODUCTION Type 2 diabetes affects 9.3% of U.S. adults [1], leading to tremendous public health and economic burden [2]. Diabetes affects racial/ethnic minority populations at disproportionately high rates [1]. The National Diabetes Prevention Program (NDPP) is the most widely available behavioral intervention to prevent diabetes [3], which is a translation of a highly successful clinical trial of intensive lifestyle support for weight loss that reduced incidence by 58% [4]. Greater engagement in the NDPP appears to yield better outcomes, but high attrition rates have been a concern [5, 6]. Retention is challenging for some racial/ethnic populations in the NDPP [6, 7]. Although resolving logistical barriers to attendance may help, such as providing childcare or transportation, a major need is to identify strategies to make the NDPP more engaging. We aimed to explore preliminary evidence for program modifications that may improve translation of the NDPP, while not detracting from its efficacy. The NDPP curriculum is published by the Centers for Disease Control and Prevention (CDC), and the most recent version was released in March 2016 [3]. To achieve weight loss the curriculum presents a goal of obtaining 150 or more minutes of weekly moderate to vigorous physical activity, a recommendation for which there has been strong evidence and national guidelines. The 2008 Physical Activity Guidelines for Americans include recommendations for at least 150 minutes of moderately intense physical activity [8]. The majority (67%) of participants in the original clinical trial of the NDPP successfully met or exceeded this physical activity goal [9]. Although physical activity was not found to be an independent predictor of diabetes incidence, participants who attained the physical activity goal without meeting the weight loss goal had a 44% reduction in incidence [10]. Yet, attaining 150 weekly minutes of physical activity appears more challenging in the NDPP than in the original clinical trial, especially for racial/ethnic minorities. A recent CDC report showed that across nationwide implementation of the NDPP, only 42% of participants met the physical activity goal, with lower attainment among participants representing racial/ethnic minorities [6]. Whether attainment of physical activity goals affects engagement in the NDPP is unknown, and merits exploration to inform future translations. We assessed effects of physical activity goal attainment on engagement and weight loss in an implementation site of the NDPP serving a large, diverse at-risk population. We predicted that black and Latino participants would have lower rates of physical activity goal attainment than nonHispanic whites. Our primary hypothesis was that participants who were less able to meet weekly physical activity goals would be more likely to drop out of the NDPP and lose less weight than participants who reported greater success. Methods We implemented the yearlong NDPP at a large safety net healthcare system serving the Denver, Colorado metro region following CDC-standardized guidelines [3]. We conducted an observational study of relationships between physical activity goal attainment and retention and weight loss in the program between March 2013 and May 2016. The Colorado Multiple Institutional Review Board approved the protocol for program evaluation. Eligibility criteria English- and Spanish-speaking adults at risk for diabetes were eligible to participate in the NDPP. Diabetes risks included a body mass index (BMI) of ≥24 (or ≥22 if Asian) and a history of recent prediabetes or gestational diabetes mellitus [11]. Prediabetes was based on a laboratory test within the past year indicating a fasting blood glucose of 100 to 125, blood glucose of 140 to 199 measured 2 hr after a 75 gm glucose load, or a hemoglobin A1c of 5.7 to 6.4. Gestational diabetes was based on a past diagnosis. Patients were also eligible based on a diabetes risk questionnaire [12]. Participants were excluded if they were pregnant at enrollment or known to have diabetes. Recruitment We identified and recruited participants through provider referrals, flyers, word of mouth, and a risk registry based on electronic medical records. Further details of our recruitment strategies have been published previously [13]. There were no costs to participate in the NDPP per grant-funding and institutional support. There were no incentives to attend or complete the program. To reduce barriers to initial engagement, participants were encouraged to attend at least one session, even if they were unable to commit upfront to a full year of NDPP classes. Eight hundred sixty-five participants attended at least one session from March 2013 to May 2016. NDPP implementation We used the 2012 NDPP curriculum with 16 weekly to biweekly sessions, followed by at least six monthly sessions over a total duration of 1 year [3]. Due to scheduling adjustments, participants who began the program in March 2013 were offered 24 NDPP sessions, while participants who began at later dates had the opportunity to participate in 22 sessions. Bilingual lay health educators completed CDC-approved training and conducted NDPP classes. Make-up sessions were provided as needed. Individuals were encouraged to lose seven percent of their body weight through diet and physical activity across the yearlong program, with an overall program goal of at least 5% average weight loss among participants. Weight was measured at each session, although the NDPP does not prescribe a weekly weight loss goal. Following the NDPP curriculum, the weekly physical activity goal of 150 min or more of moderate to vigorous intensity was introduced in the fifth session. The curriculum recommends beginning physical activity gradually as needed (e.g., “Work up to the 150-min goal slowly. It may take about 4 weeks to do so.”) Participants were instructed to track start and stop times and report their total weekly minutes of physical activity at the following session. As such, physical activity was reported at the sixth and all subsequent sessions. Although the NDPP curriculum was revised in 2016, there were no major changes in physical activity instruction from the 2012 version. Participants were also encouraged to eat 25% or less of calories from fat, but dietary adherence was not recorded and is no longer a program goal in the revised curriculum. Thus, we focused this evaluation on physical activity as the only frequently prescribed and monitored behavioral goal in the NDPP. Study sample To focus on effects of physical activity goal attainment, for this analysis we included 406 participants (46.9% of the overall sample) who attended the NDPP after physical activity was first reported in the sixth session given physical activity was not yet monitored in sessions 1–5. We further excluded 15 participants who did not report physical activity for a final sample of 391 participants. Measures Demographic and baseline health characteristics included race/ethnicity, language, age, gender, and baseline BMI and hemoglobin A1c, which were extracted from electronic health records. Physical activity was assessed as self-reported minutes of moderate to vigorous activity completed in the previous week. We operationalized physical activity goal attainment as the percentage of times in which participants reported meeting or exceeding weekly physical activity goals compared to the total number of times in which they reported activity. For example, a participant who reported achieving ≥150 min of physical activity for four of 10 weeks was assigned a goal achievement percentage of 40%. As participants may have begun physical activity gradually in the first four weeks per curriculum guidance, we further assessed goal attainment for sessions 6–9 versus 10+ to inform whether goal attainment across the NDPP was an appropriate measure for hypothesis testing. We assessed the total percent of NDPP sessions attended. We also evaluated the percent of participants who completed the program. Per CDC standards, completion was defined as attending at least nine classes in the first 6 months, plus three or more sessions attended in months 7 through 12 [11]. Baseline weight was defined as a participant’s weight at their first session attended. Final weight was based on the last session each participant attended. We calculated the (a) average percent weight change per session attended, (b) total percent weight change from a participant’s baseline weight to their final session attended, and (c) proportion of participants who achieved at least 5% weight loss. Although the NDPP’s objective is diabetes prevention, weight loss is the primary outcome and glucose or A1c outcomes are not measured. Analysis Differences in characteristics between the study sample and excluded individuals who dropped out prior to introduction of physical activity goals were assessed using t-tests and chi-square tests. We then assessed descriptive statistics for sociodemographic and baseline health characteristics, physical activity, attendance, and weight loss outcomes. We used t-tests and linear regression to examine sociodemographic differences in rates of attaining physical activity goals. We focused our analysis on goal attainment rather than the total amount of physical activity to assess the impact of goal attainment versus failure on engagement. We compared rates of goal attainment in early versus later sessions using a paired t-test. We used multivariate linear and logistic regression to determine associations of physical activity goal attainment on attendance and weight change. Covariates included age, gender, race/ethnicity, baseline BMI, and baseline hemoglobin A1c, which were previously found to predict differences in physical activity levels among participants in the original clinical trial [14]. Finally, we used logistic regression in a post hoc analysis to determine whether participants who reported failing to achieve physical activity goals at one session were less likely to attend the next scheduled session. SPSS version 21 was used for all analyses. RESULTS Descriptive results Characteristics of the study sample are presented in Table 1. Participants had a mean age of 51.9 (SD = 12.6) and tended to be female (n = 298; 77.0%). Over half of participants were of Latino ethnicity (n = 200; 53.9%), whereas 23.2% were nonHispanic Black (n = 86), and 21.8% were nonHispanic White (n = 81). The average BMI at program entry was 34.6 (SD = 7.5). Mean hemoglobin A1c at program entry was 6.0 (SD = 0.5). Of participants who started the NDPP, comparably fewer Latinos continued to session six and beyond when physical activity was measured (p < .05); in contrast, relatively more African American participants continued in the program (p < .05). No other characteristics significantly differed between the study sample and excluded individuals. Table 1 Participant characteristics and outcomes in the national diabetes prevention program (N = 391)a Variable n (%) or M (SD) Age 51.9 (12.6) Female gender 298 (77.0) Race/Ethnicity  Latino 200 (53.9)  Black 86 (23.2)  White 81 (21.8)  Other/unknown 24 (6.1) Baseline body mass index 34.6 (7.5) Baseline hemoglobin A1c 6.0 (0.5) Weekly minutes of physical activity 198.4 (139.7) Percent weekly physical activity goal attainment 52.7 (35.1) Percent of sessions attended 65.8 (24.2) Average percent weight loss per session attended 0.22 (0.37) Percent weight loss 3.4 (5.8) Obtained ≥5% weight loss 132 (33.8) Variable n (%) or M (SD) Age 51.9 (12.6) Female gender 298 (77.0) Race/Ethnicity  Latino 200 (53.9)  Black 86 (23.2)  White 81 (21.8)  Other/unknown 24 (6.1) Baseline body mass index 34.6 (7.5) Baseline hemoglobin A1c 6.0 (0.5) Weekly minutes of physical activity 198.4 (139.7) Percent weekly physical activity goal attainment 52.7 (35.1) Percent of sessions attended 65.8 (24.2) Average percent weight loss per session attended 0.22 (0.37) Percent weight loss 3.4 (5.8) Obtained ≥5% weight loss 132 (33.8) aData are presented as mean (standard deviation) and frequency (%). View Large Table 1 Participant characteristics and outcomes in the national diabetes prevention program (N = 391)a Variable n (%) or M (SD) Age 51.9 (12.6) Female gender 298 (77.0) Race/Ethnicity  Latino 200 (53.9)  Black 86 (23.2)  White 81 (21.8)  Other/unknown 24 (6.1) Baseline body mass index 34.6 (7.5) Baseline hemoglobin A1c 6.0 (0.5) Weekly minutes of physical activity 198.4 (139.7) Percent weekly physical activity goal attainment 52.7 (35.1) Percent of sessions attended 65.8 (24.2) Average percent weight loss per session attended 0.22 (0.37) Percent weight loss 3.4 (5.8) Obtained ≥5% weight loss 132 (33.8) Variable n (%) or M (SD) Age 51.9 (12.6) Female gender 298 (77.0) Race/Ethnicity  Latino 200 (53.9)  Black 86 (23.2)  White 81 (21.8)  Other/unknown 24 (6.1) Baseline body mass index 34.6 (7.5) Baseline hemoglobin A1c 6.0 (0.5) Weekly minutes of physical activity 198.4 (139.7) Percent weekly physical activity goal attainment 52.7 (35.1) Percent of sessions attended 65.8 (24.2) Average percent weight loss per session attended 0.22 (0.37) Percent weight loss 3.4 (5.8) Obtained ≥5% weight loss 132 (33.8) aData are presented as mean (standard deviation) and frequency (%). View Large The average percentage of success attaining weekly physical activity goals across the duration of the yearlong program was 52.7% (SD = 35.1), meaning participants reported meeting or exceeding physical activity goals about half of the time on average. There was no significant difference in rates of goal attainment between early versus later sessions: 52.8% (SD = 43.0) and 54.6% (SD = 35.6), respectively, p = 0.598. Only 17.9% of participants (n = 70) fully met or exceeded weekly physical activity goals on all occasions. Men had higher rates of attaining weekly physical activity goals than women, 61.7% (SD = 35.7) versus 49.8% (SD = 34.4), respectively, p < .01. Percent of physical activity goal attainment among Latino and black participants were 51.2% (SD = 34.5) and 53.5% (SD = 33.4), respectively, while percent goal attainment among white participants was 58.3% (SD = 36.6). In contrast to our hypothesized prediction, these differences were not statistically significant. There were also no significant differences in achieving physical activity goals by age, baseline BMI, or baseline A1c. Average reported weekly physical activity was 198.4 min (SD = 139.7) across all participants. Although average physical activity for the overall sample exceeded 150 weekly minutes, examining results by a median split of percent goal attainment (median = 53.8%) indicated high variability between groups. Participants above the median (high goal attainment group) reported 286.6 average weekly minutes of physical activity (SD = 142.5); those below the median (low goal attainment group) reported 109.7 min (SD = 55.4) on average. Participants attended 65.8% (SD = 24.2) of all NDPP sessions on average. Mean attendance was 15.6 (65.0%) sessions (SD = 5.8) among 97 participants who were offered 24 sessions. For 294 participants who were offered up to 22 sessions, average attendance was 14.5 (65.9%) sessions (SD = 5.3). Of the participants, 39% (n = 152) fully completed the yearlong program per CDC standards. Mean weight loss was 3.4% (SD = 5.8). The average rate of weight loss per session attended was 0.22% (SD = 0.37). Approximately one third (33.8%) of participants (n = 132) achieved at least 5% weight loss. Regression results Table 2 presents a summary of multiple linear and logistic regression analyses for effects of physical activity goal attainment on attendance and weight loss in the NDPP. Supporting our primary hypothesis, there was a linear relationship between physical activity goal attainment and percent of sessions attended, β = 0.21 (p < .01). For each 10% decrease in physical activity goal attainment, participants had a 5.3% lower likelihood of completing the program (OR 0.47; p < .05; 95% CI 0.24–0.90). Each occurrence of not attaining the physical activity goal of 150 min/week predicted a 25% lower likelihood of attending the next scheduled session (OR 0.75; p < .001; 95% CI 0.64–0.87). This within-subjects analysis was intended to further assess a possible causal relationship between goal attainment and engagement. There was also a linear relationship between physical activity goal attainment and total percent weight loss, β = −0.14 (p < .05). There was no significant relationship between physical activity goal attainment and weight change per session attended. For every 10% decrease in physical activity goal attainment, participants had a 6.1% lower likelihood of achieving at least five percent weight loss (OR 0.39; p < .01; 95% CI 0.19–0.76). Table 2 Summary of multiple linear and logistic regression analyses for attendance and weight loss by physical activity goal attainment (N = 391)a B SE(B) β t p value Percent of sessions attended** 0.14 0.04 0.21 3.18 .002 Percent of weight change by session attended −0.08 0.06 −0.07 −1.30 .194 Total percent weight change* −2.26 0.93 −0.14 −2.43 .016 Exp(B) 95% CI p value Completed program* 0.76 0.34 0.47 0.24–0.90 .024 Obtained ≥5% weight loss** 0.94 0.36 0.39 0.19–0.76 .008 B SE(B) β t p value Percent of sessions attended** 0.14 0.04 0.21 3.18 .002 Percent of weight change by session attended −0.08 0.06 −0.07 −1.30 .194 Total percent weight change* −2.26 0.93 −0.14 −2.43 .016 Exp(B) 95% CI p value Completed program* 0.76 0.34 0.47 0.24–0.90 .024 Obtained ≥5% weight loss** 0.94 0.36 0.39 0.19–0.76 .008 aModels were adjusted for age, gender, race/ethnicity, baseline body mass index, and baseline A1c. *p < .05; **p < .01. View Large Table 2 Summary of multiple linear and logistic regression analyses for attendance and weight loss by physical activity goal attainment (N = 391)a B SE(B) β t p value Percent of sessions attended** 0.14 0.04 0.21 3.18 .002 Percent of weight change by session attended −0.08 0.06 −0.07 −1.30 .194 Total percent weight change* −2.26 0.93 −0.14 −2.43 .016 Exp(B) 95% CI p value Completed program* 0.76 0.34 0.47 0.24–0.90 .024 Obtained ≥5% weight loss** 0.94 0.36 0.39 0.19–0.76 .008 B SE(B) β t p value Percent of sessions attended** 0.14 0.04 0.21 3.18 .002 Percent of weight change by session attended −0.08 0.06 −0.07 −1.30 .194 Total percent weight change* −2.26 0.93 −0.14 −2.43 .016 Exp(B) 95% CI p value Completed program* 0.76 0.34 0.47 0.24–0.90 .024 Obtained ≥5% weight loss** 0.94 0.36 0.39 0.19–0.76 .008 aModels were adjusted for age, gender, race/ethnicity, baseline body mass index, and baseline A1c. *p < .05; **p < .01. View Large DISCUSSION This study explored possible effects of physical activity goal attainment on engagement and outcomes in an intervention to prevent diabetes, which has not been reported on previously to our knowledge. We found that approximately half of NDPP participants achieved the goal of 150 weekly minutes of physical activity, compared to about two thirds of participants in the original trial [9]. Women were less likely to attain physical activity goals than men, although more women than men enrolled in the NDPP, consistent with national dissemination results [6]. Although Latino and black participants reported lower levels of goal attainment than white participants, racial/ethnic differences in physical activity goal attainment were not statistically significant. Notably, findings suggest that the extent to which participants met physical activity goals did not affect rates of weight loss per session attended. Yet, less success achieving physical activity goals was associated with less participation and less total weight loss in the NDPP, which supported our primary hypothesis. Difficulty achieving physical activity goals is consistent with previous findings that many participants in the original clinical trial on which the NDPP is based were unable to attain physical activity goals [9], and that women with diabetes risks are less active than men [6, 14]. Although previous literature has shown racial/ethnic differences in physical activity levels [6, 14], trends reported here were not significant. To reduce diabetes incidence, it may be important to encourage continued engagement among individuals who struggle to achieve 150 weekly minutes of physical activity, including women. Moreover, it may be beneficial to place greater emphasis on setting personalized physical activity goals throughout the NDPP to address the needs and capabilities of each participant. This is consistent with a systematic review of necessary intervention components for diabetes prevention that found evidence supporting motivational interviewing motivational interviewing and individualized tailoring of recommendations, rather than prescriptive guidance [15]. At the same time, it remains critical to support participants in working toward achieving evidence-based guidelines for physical activity, which is important for reducing both diabetes risk [10] and all-cause mortality [16]. Higher exercise self-efficacy and readiness for change, and lower anxiety, depression, and stress were found to predict physical activity in the seminal diabetes prevention study [17], so it may also be important to assess and address these factors in future diabetes prevention efforts. Limitations Results are not fully generalizable as this was a quality improvement program with an observational study design. We conducted the NDPP in a safety net healthcare system where many patients are low-income and have government insurance, so they may have had fewer resources with which to engage in physical activity than the general population. Physical activity was based on self-report. Several analyses were correlational in nature due to the simultaneous assessment of physical activity, engagement, and weight loss. Nonetheless, findings from the post hoc analysis further supported the possibility of a causal relationship between failing to achieve physical activity goals at one session and a lower likelihood of attending the next scheduled session. We were unable to account for possible alternative explanations. We did not assess motivation to engage in the NDPP, which could underlie the relationship between physical activity goal attainment and participation. We also did not systematically assess perceived barriers to physical activity and participation in the NDPP. Participants may have been unable to complete the program for the same reasons that they had challenges attaining physical activity goals, such as due to caregiving responsibilities. Participants may also have self-selected personal goals of less than 150 weekly activity minutes, which could alter perceptions of and responses to goal attainment. Finally, participants who attended a greater number of sessions had more opportunities to report physical activity than those who attended fewer sessions. Yet, we could not control for attendance as reporting activity was dependent on participants coming to sessions. We sought to capture the relative experience of goal success versus failure regardless of the number of sessions attended by using percentage of weekly physical activity goal attainment as the primary predictor. Future research Further evidence is needed to confirm the effects of physical activity goal attainment on engagement and outcomes in the NDPP, including glucose and/or A1c as direct indicators of diabetes risks. Suggestions for more rigorous research include conducting an experiment in which participants are randomized to receive guidance using similar prescriptive recommendations for physical activity as compared to a patient-centered approach in which participants are encouraged to “do the best that you can.” Suggested future qualitative research includes interviewing participants to see if they identify prescriptive physical activity goals as problematic, as well as what other factors contribute to drop out. Efforts are needed to determine what modifications are needed to support risk reduction behaviors among women with diabetes risks. Although we did not find significant racial/ethnic differences in physical activity goal attainment, previous research and trends reported here suggest further research may also be needed to determine culturally appropriate messages for setting physical activity goals. Conclusion Preliminary evidence from this observational study suggests that failing to attain physical activity goals may be a deterrent to persistence in the NDPP. At the same time, the extent to which participants achieved 150 weekly minutes of physical activity did not affect NDPP efficacy in terms of the rate of weight loss per session attended. The key question these findings raise is whether participants who fail to achieve physical activity goals would be more likely to stay in the program longer, and thus lose more weight and better prevent diabetes, if the NDPP curriculum was modified to present goals in a more patient-centered manner. This relationship needs further attention to support development of improved diabetes prevention strategies. Acknowledgments The findings and manuscript have been submitted solely to TBM and have not been previously published or posted online. A poster of this work was presented on March 30, 2017 at the Society for Behavioral Medicine annual meeting. The authors have full control of all primary data and we agree to allow the journal to review our data if requested. This work was funded by the Amendment 35 Cancer, Cardiovascular Disease and Pulmonary Disease Grant Program administered by the Colorado Department of Public Health and Environment, as well as an award from America’s Health Insurance Plans in partnership with the Centers for Disease Control and Prevention. Denver Health and Hospital Authority provided additional financial support. The contents of this publication are solely the responsibility of the authors and do not represent official views of these organizations. The Colorado Multiple Institutional Review Board approved the protocol for program evaluation (i.e., nonhuman subject research). As such, informed consent requirements were waived. No animals were involved. Compliance with Ethical Standards Conflict of interest: Natalie D. Ritchie, Jennifer K. Carroll, Jodi Summers Holtrop, and Edward P. Havranek have no conflict of interest to report. References 1. Centers for Disease Control and Prevention (CDC) . National Diabetes Statistics Report: Estimates of Diabetes and its Burden in the United States, 2014 . Atlanta, GA : CDC, US Department of Health and Human Services ; 2014 . 2. American Diabetes Association . Economic costs of diabetes in the US in 2012 . Diabetes Care . 2013 ; 36 ( 4 ): 1033 – 1046 . Crossref Search ADS PubMed 3. CDC . National Diabetes Prevention Program ; 2016 . Available at https://www.cdc.gov/diabetes/prevention/lifestyle-program/curriculum.html. Accessibility verified March 7, 2017 . 4. Knowler WC , Barrett-Connor E , Fowler SE , et al. ; Diabetes Prevention Program Research Group . Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin . N Engl J Med . 2002 ; 346 ( 6 ): 393 – 403 . Google Scholar Crossref Search ADS PubMed 5. Ali MK , Echouffo-Tcheugui J , Williamson DF . How effective were lifestyle interventions in real-world settings that were modeled on the Diabetes Prevention Program ? Health Aff (Millwood) . 2012 ; 31 ( 1 ): 67 – 75 . Google Scholar Crossref Search ADS PubMed 6. Ely EK , Gruss SM , Luman ET , Albright AL . Response to comment on Ely et al. A national effort to prevent type 2 diabetes: Participant-level evaluation of CDC’s National Diabetes Prevention Program. Diabetes Care 2017; 40:1331-1341 . Diabetes Care . 2017 ; 40 ( 11 ): e163 . Google Scholar Crossref Search ADS PubMed 7. Ritchie ND , Christoe-Frazier L , McFann KK , Havranek EP , Pereira RI . Effect of the national diabetes prevention program on weight loss for English- and Spanish-speaking Latinos . Am J Health Promot . 2017 . doi: 10.1177/0890117117698623 . 8. Physical Activity Guidelines Advisory Committee . Physical activity guidelines for Americans . Washington, DC : US Department of Health and Human Services ; 2008 : 15 – 34 . 9. Wing RR , Hamman RF , Bray GA , et al. ; Diabetes Prevention Program Research Group . Achieving weight and activity goals among diabetes prevention program lifestyle participants . Obes Res . 2004 ; 12 ( 9 ): 1426 – 1434 . Google Scholar Crossref Search ADS PubMed 10. Hamman RF , Wing RR , Edelstein SL , et al. Effect of weight loss with lifestyle intervention on risk of diabetes . Diabetes Care . 2006 ; 29 ( 9 ): 2102 – 2107 . Google Scholar Crossref Search ADS PubMed 11. CDC . CDC Diabetes Prevention Recognition Program Standards and Operating Procedures ; 2015 . Available at http://www.cdc.gov/diabetes/prevention/pdf/dprp-standards.pdf. Accessibility verified November 7, 2016 . 12. CDC . CDC Prediabetes Screening Test . Available at http://www.cdc.gov/diabetes/prevention/pdf/prediabetestest.pdf. Accessibility verified February 13, 2017 . 13. Ritchie N , Swigert T . Establishing an effective primary care provider referral network for the National Diabetes Prevention Program . AADE in Practice . 2016 ; 4 ( 4 ): 20 – 25 . Google Scholar Crossref Search ADS 14. Kriska AM , Edelstein SL , Hamman RF , et al. Physical activity in individuals at risk for diabetes: Diabetes Prevention Program . Med Sci Sports Exerc . 2006 ; 38 ( 5 ): 826 – 832 . Google Scholar Crossref Search ADS PubMed 15. Greaves CJ , Sheppard KE , Abraham C , et al. ; IMAGE Study Group . Systematic review of reviews of intervention components associated with increased effectiveness in dietary and physical activity interventions . BMC Public Health . 2011 ; 11 : 119 . Google Scholar Crossref Search ADS PubMed 16. Schmid D , Ricci C , Leitzmann MF . Associations of objectively assessed physical activity and sedentary time with all-cause mortality in US adults: the NHANES study . PLoS One . 2015 ; 10 ( 3 ): e0119591 . Google Scholar Crossref Search ADS PubMed 17. Delahanty LM , Conroy MB , Nathan DM ; Diabetes Prevention Program Research Group . Psychological predictors of physical activity in the diabetes prevention program . J Am Diet Assoc . 2006 ; 106 ( 5 ): 698 – 705 . Google Scholar Crossref Search ADS PubMed © Society of Behavioral Medicine 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Journal

Translational Behavioral MedicineOxford University Press

Published: Nov 21, 2018

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