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Acute Kidney Injury: Comment on “Trends in the Incidence of Acute Kidney Injury in Patients Hospitalized With Acute Myocardial Infarction”

Acute Kidney Injury: Comment on “Trends in the Incidence of Acute Kidney Injury in Patients... While acute kidney injury (AKI), a newer term for acute renal failure, has long been recognized as a common and serious complication of hospitalized patients, the study of AKI epidemiology has lagged. An important advance took place with the introduction of consensus AKI definitions by expert panels—first the Risk, Injury, Failure, Loss, and ESRD (RIFLE) criteria by the Acute Dialysis Quality Initiative in 2004,1 and then the Acute Kidney Injury Network (AKIN) criteria in 2007.2 These have allowed researchers to examine AKI epidemiology using a common case definition and to overcome one important limitation in the prior literature when cases were defined using different criteria in different studies, rendering it difficult to interpret variations in reported disease incidence. Since then, several studies have characterized AKI incidence in various settings, with wide range of incidences across different hospital and intensive care unit cohorts,3,4 but relatively few studies have examined secular trends in AKI epidemiology. In this issue of the Archives, Amin et al5 used a large registry of electronic records from 56 US hospitals to explore the temporal trend in the AKI incidence among patients hospitalized with acute myocardial infarction. They observed an overall decline in crude AKI incidence from 26.6% in 2000 to 19.7% in 2008, an overall adjusted decline of 4.4% per year. The study is strengthened by the authors' careful consideration to extensively adjust for demographic variables (age, race/ethnicity, sex) and comorbidities (presence of diabetes mellitus, heart failure, cardiogenic shock, and baseline renal function) that are known AKI risk factors, along with surveillance patterns for AKI, to ensure that the observed temporal trend is not due to an aging and sicker population over time or due to differences in vigilance of renal function monitoring. The data's robustness is further supported by the authors' thoughtful sensitivity analyses ensuring that the duration of hospital participation in the database and severity of AKI did not account for the observed overall trend. The findings are different from those of prior studies demonstrating a rising incidence of AKI. One study using national representative hospital discharge data had shown an increase in AKI incidence on a population level from 1988 to 2002 in the United States.6 Another study using data from a large Northern California integrated health system found a parallel increase in the population incidence of both dialysis-requiring and non–dialysis requiring AKI from 1996 to 2003.7 The availability of actual serum creatinine measurements in the latter study is important since International Classification of Diseases, Ninth Revision (ICD-9) codes for non–dialysis requiring AKI is known to be insensitive and suffer “code-creep” bias.8 These discrepant trends suggest that AKI may be occurring more frequently overall but occurs less commonly in certain subgroups of patients (eg, those with acute myocardial infarction). Certain clues from the current study shed light on possible reasons AKI incidence is declining, specifically in patients with acute myocardial infarction. The authors performed important stratified analyses demonstrating a more prominent decline in AKI incidence in patients with acute myocardial infarction who underwent cardiac catheterization than in those who did not. In addition, they also demonstrated a significant trend in the increasingly more pervasive use of N-acetyl cysteine over time. Since it is not clear that N-acetyl cysteine is effective,9 its use may be a marker for better process of care. These findings suggest that the decline in AKI incidence may be due to improved efforts at preventing contrast-induced AKI in those undergoing cardiac catheterization, such as adequate hydration and limiting contrast load. The interesting subanalysis finding of wide hospital variations in AKI incidence after multivariable adjustment further support that differing practice patterns (ie, systems-based protocols or angiographer skill levels) may play a role specifically in the incidence of contrast-induced AKI. This is a hopeful message. Although current treatment after onset of AKI is largely supportive, prevention of AKI may be a fruitful area of endeavor. Future work needs to be performed on several fronts. One, further population-based epidemiology studies should be conducted to better define contemporary AKI disease incidence—overall and in specific demographic, clinical, and geographic subgroups.10 Two, if the incidence of AKI is increasing overall but falling in some subgroups (eg, among patients with acute myocardial infarction), we need to understand what is driving up the AKI rate in other groups. Three, we need to understand determinants of variations in AKI in a particular setting and identify modifiable risk factors in order to find effective preventive therapies. Finally, in the future, we may be able to adopt AKI incidence among hospitalized patients as a quality and safety outcome measure, akin to the incidence of central line infections, or the incidence of decubitus ulcers among hospitalized patients,11 as focusing attention to this may translate into considerable improvements in patient outcomes. Back to top Article Information Correspondence: Dr Chi-yuan Hsu, Division of Nephrology, University of California, San Francisco, 521 Parnassus Ave, C443, PO Box 0532, San Francisco, CA 94143 (hsuchi@medicine.ucsf.edu). Financial Disclosure: None reported. References 1. Bellomo R, Ronco C, Kellum JA, Mehta RL, Palevsky P.Acute Dialysis Quality Initiative Workgroup. Acute renal failure: definition, outcome measures, animal models, fluid therapy and information technology needs: the Second International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group. Crit Care. 2004;8(4):R204-R21215312219PubMedGoogle ScholarCrossref 2. Mehta RL, Kellum JA, Shah SV, et al; Acute Kidney Injury Network. Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury. Crit Care. 2007;11(2):R3117331245PubMedGoogle ScholarCrossref 3. Bagshaw SM, George C, Bellomo R.ANZICS Database Management Committee. A comparison of the RIFLE and AKIN criteria for acute kidney injury in critically ill patients. Nephrol Dial Transplant. 2008;23(5):1569-157418281319PubMedGoogle ScholarCrossref 4. Thakar CV, Christianson A, Freyberg R, Almenoff P, Render ML. Incidence and outcomes of acute kidney injury in intensive care units: a Veterans Administration study. Crit Care Med. 2009;37(9):2552-255819602973PubMedGoogle ScholarCrossref 5. Amin AP, Salisbury AC, McCullough PA, et al. Trends in the incidence of acute kidney injury in patients hospitalized with acute myocardial infarction. Arch Intern Med. 2012;172(3):246-253Google ScholarCrossref 6. Waikar SS, Curhan GC, Wald R, McCarthy EP, Chertow GM. Declining mortality in patients with acute renal failure, 1988 to 2002. J Am Soc Nephrol. 2006;17(4):1143-115016495376PubMedGoogle ScholarCrossref 7. Hsu CY, McCulloch CE, Fan D, Ordoñez JD, Chertow GM, Go AS. Community-based incidence of acute renal failure. Kidney Int. 2007;72(2):208-21217507907PubMedGoogle ScholarCrossref 8. Waikar SS, Wald R, Chertow GM, et al. Validity of International Classification of Diseases, Ninth Revision, Clinical Modification, codes for acute renal failure. J Am Soc Nephrol. 2006;17(6):1688-169416641149PubMedGoogle ScholarCrossref 9. ACT Investigators. Acetylcysteine for prevention of renal outcomes in patients undergoing coronary and peripheral vascular angiography: main results from the randomized Acetylcysteine for Contrast-induced nephropathy Trial (ACT). Circulation. 2011;124(11):1250-125921859972PubMedGoogle ScholarCrossref 10. Hsu CY. Where is the epidemic in kidney disease? J Am Soc Nephrol. 2010;21(10):1607-161120813868PubMedGoogle ScholarCrossref 11. AHRQ Quality Indicators: Guide to Patient Safety Indicators. Department of Health and Human Services, Agency for Healthcare Research and Quality Web site. http://www.qualityindicators.ahrq.gov/Downloads/Software/SAS/V30/psi_guide_v30.pdf. Accessed December 12, 2011 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Internal Medicine American Medical Association

Acute Kidney Injury: Comment on “Trends in the Incidence of Acute Kidney Injury in Patients Hospitalized With Acute Myocardial Infarction”

Archives of Internal Medicine , Volume 172 (3) – Feb 13, 2012

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Publisher
American Medical Association
Copyright
Copyright © 2012 American Medical Association. All Rights Reserved.
ISSN
0003-9926
eISSN
1538-3679
DOI
10.1001/archinternmed.2011.1606
Publisher site
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Abstract

While acute kidney injury (AKI), a newer term for acute renal failure, has long been recognized as a common and serious complication of hospitalized patients, the study of AKI epidemiology has lagged. An important advance took place with the introduction of consensus AKI definitions by expert panels—first the Risk, Injury, Failure, Loss, and ESRD (RIFLE) criteria by the Acute Dialysis Quality Initiative in 2004,1 and then the Acute Kidney Injury Network (AKIN) criteria in 2007.2 These have allowed researchers to examine AKI epidemiology using a common case definition and to overcome one important limitation in the prior literature when cases were defined using different criteria in different studies, rendering it difficult to interpret variations in reported disease incidence. Since then, several studies have characterized AKI incidence in various settings, with wide range of incidences across different hospital and intensive care unit cohorts,3,4 but relatively few studies have examined secular trends in AKI epidemiology. In this issue of the Archives, Amin et al5 used a large registry of electronic records from 56 US hospitals to explore the temporal trend in the AKI incidence among patients hospitalized with acute myocardial infarction. They observed an overall decline in crude AKI incidence from 26.6% in 2000 to 19.7% in 2008, an overall adjusted decline of 4.4% per year. The study is strengthened by the authors' careful consideration to extensively adjust for demographic variables (age, race/ethnicity, sex) and comorbidities (presence of diabetes mellitus, heart failure, cardiogenic shock, and baseline renal function) that are known AKI risk factors, along with surveillance patterns for AKI, to ensure that the observed temporal trend is not due to an aging and sicker population over time or due to differences in vigilance of renal function monitoring. The data's robustness is further supported by the authors' thoughtful sensitivity analyses ensuring that the duration of hospital participation in the database and severity of AKI did not account for the observed overall trend. The findings are different from those of prior studies demonstrating a rising incidence of AKI. One study using national representative hospital discharge data had shown an increase in AKI incidence on a population level from 1988 to 2002 in the United States.6 Another study using data from a large Northern California integrated health system found a parallel increase in the population incidence of both dialysis-requiring and non–dialysis requiring AKI from 1996 to 2003.7 The availability of actual serum creatinine measurements in the latter study is important since International Classification of Diseases, Ninth Revision (ICD-9) codes for non–dialysis requiring AKI is known to be insensitive and suffer “code-creep” bias.8 These discrepant trends suggest that AKI may be occurring more frequently overall but occurs less commonly in certain subgroups of patients (eg, those with acute myocardial infarction). Certain clues from the current study shed light on possible reasons AKI incidence is declining, specifically in patients with acute myocardial infarction. The authors performed important stratified analyses demonstrating a more prominent decline in AKI incidence in patients with acute myocardial infarction who underwent cardiac catheterization than in those who did not. In addition, they also demonstrated a significant trend in the increasingly more pervasive use of N-acetyl cysteine over time. Since it is not clear that N-acetyl cysteine is effective,9 its use may be a marker for better process of care. These findings suggest that the decline in AKI incidence may be due to improved efforts at preventing contrast-induced AKI in those undergoing cardiac catheterization, such as adequate hydration and limiting contrast load. The interesting subanalysis finding of wide hospital variations in AKI incidence after multivariable adjustment further support that differing practice patterns (ie, systems-based protocols or angiographer skill levels) may play a role specifically in the incidence of contrast-induced AKI. This is a hopeful message. Although current treatment after onset of AKI is largely supportive, prevention of AKI may be a fruitful area of endeavor. Future work needs to be performed on several fronts. One, further population-based epidemiology studies should be conducted to better define contemporary AKI disease incidence—overall and in specific demographic, clinical, and geographic subgroups.10 Two, if the incidence of AKI is increasing overall but falling in some subgroups (eg, among patients with acute myocardial infarction), we need to understand what is driving up the AKI rate in other groups. Three, we need to understand determinants of variations in AKI in a particular setting and identify modifiable risk factors in order to find effective preventive therapies. Finally, in the future, we may be able to adopt AKI incidence among hospitalized patients as a quality and safety outcome measure, akin to the incidence of central line infections, or the incidence of decubitus ulcers among hospitalized patients,11 as focusing attention to this may translate into considerable improvements in patient outcomes. Back to top Article Information Correspondence: Dr Chi-yuan Hsu, Division of Nephrology, University of California, San Francisco, 521 Parnassus Ave, C443, PO Box 0532, San Francisco, CA 94143 (hsuchi@medicine.ucsf.edu). Financial Disclosure: None reported. References 1. Bellomo R, Ronco C, Kellum JA, Mehta RL, Palevsky P.Acute Dialysis Quality Initiative Workgroup. Acute renal failure: definition, outcome measures, animal models, fluid therapy and information technology needs: the Second International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group. Crit Care. 2004;8(4):R204-R21215312219PubMedGoogle ScholarCrossref 2. Mehta RL, Kellum JA, Shah SV, et al; Acute Kidney Injury Network. Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury. Crit Care. 2007;11(2):R3117331245PubMedGoogle ScholarCrossref 3. Bagshaw SM, George C, Bellomo R.ANZICS Database Management Committee. A comparison of the RIFLE and AKIN criteria for acute kidney injury in critically ill patients. Nephrol Dial Transplant. 2008;23(5):1569-157418281319PubMedGoogle ScholarCrossref 4. Thakar CV, Christianson A, Freyberg R, Almenoff P, Render ML. Incidence and outcomes of acute kidney injury in intensive care units: a Veterans Administration study. Crit Care Med. 2009;37(9):2552-255819602973PubMedGoogle ScholarCrossref 5. Amin AP, Salisbury AC, McCullough PA, et al. Trends in the incidence of acute kidney injury in patients hospitalized with acute myocardial infarction. Arch Intern Med. 2012;172(3):246-253Google ScholarCrossref 6. Waikar SS, Curhan GC, Wald R, McCarthy EP, Chertow GM. Declining mortality in patients with acute renal failure, 1988 to 2002. J Am Soc Nephrol. 2006;17(4):1143-115016495376PubMedGoogle ScholarCrossref 7. Hsu CY, McCulloch CE, Fan D, Ordoñez JD, Chertow GM, Go AS. Community-based incidence of acute renal failure. Kidney Int. 2007;72(2):208-21217507907PubMedGoogle ScholarCrossref 8. Waikar SS, Wald R, Chertow GM, et al. Validity of International Classification of Diseases, Ninth Revision, Clinical Modification, codes for acute renal failure. J Am Soc Nephrol. 2006;17(6):1688-169416641149PubMedGoogle ScholarCrossref 9. ACT Investigators. Acetylcysteine for prevention of renal outcomes in patients undergoing coronary and peripheral vascular angiography: main results from the randomized Acetylcysteine for Contrast-induced nephropathy Trial (ACT). Circulation. 2011;124(11):1250-125921859972PubMedGoogle ScholarCrossref 10. Hsu CY. Where is the epidemic in kidney disease? J Am Soc Nephrol. 2010;21(10):1607-161120813868PubMedGoogle ScholarCrossref 11. AHRQ Quality Indicators: Guide to Patient Safety Indicators. Department of Health and Human Services, Agency for Healthcare Research and Quality Web site. http://www.qualityindicators.ahrq.gov/Downloads/Software/SAS/V30/psi_guide_v30.pdf. Accessed December 12, 2011

Journal

Archives of Internal MedicineAmerican Medical Association

Published: Feb 13, 2012

Keywords: myocardial infarction, acute,renal failure, acute

References