Some methodological issues in studying the long-term renal sequelae of acute kidney injury.
ABSTRACT There has been great interest recently in better understanding how an episode of acute kidney injury (AKI) affects risk of development or acceleration of chronic kidney disease. This area of epidemiology research presents several methodological challenges that have not been sufficiently discussed in the literature. These are related to the current consensus definitions of AKI; the determination of 'baseline' renal function before the AKI episode; and the possibility that observed associations between AKI and future adverse events are confounded by differences in the severity of baseline chronic kidney disease. In this study, we discuss several potential solutions to these problems. Concerted efforts to address these methodological issues will propel research in this field to a higher level.
Clinical Journal of the American Society of Nephrology 01/2013; 8(2). DOI:10.2215/CJN.12621212 · 5.25 Impact Factor
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ABSTRACT: IMPORTANCE Most acute kidney injury observed in the hospital is defined by sudden mild or moderate increases in the serum creatinine concentration, which may persist for several days. Such acute kidney injury is associated with lower long-term kidney function. However, it has not been demonstrated that an intervention that reduces the risk of such acute kidney injury better preserves long-term kidney function. OBJECTIVES To characterize the risk of acute kidney injury with an intervention in a randomized clinical trial and to determine if there is a difference between the 2 treatment groups in kidney function 1 year later. DESIGN, SETTING, AND PARTICIPANTS The Coronary Artery Bypass Grafting Surgery Off- or On-pump Revascularisation Study (CORONARY) enrolled 4752 patients undergoing first isolated coronary artery bypass graft (CABG) surgery at 79 sites in 19 countries. Patients were randomized to receive CABG surgery either with a beating-heart technique (off-pump) or with cardiopulmonary bypass (on-pump). From January 2010 to November 2011, 2932 patients (from 63 sites in 16 countries) from CORONARY were enrolled into a kidney function substudy to record serum creatinine concentrations during the postoperative period and at 1 year. The last 1-year serum creatinine concentration was recorded on January 18, 2013. MAIN OUTCOMES AND MEASURES Acute kidney injury within 30 days of surgery (50% increase in serum creatinine concentration from prerandomization concentration) and loss of kidney function at 1 year (20% loss in estimated glomerular filtration rate from prerandomization level). RESULTS Off-pump (n = 1472) vs on-pump (n = 1460) CABG surgery reduced the risk of acute kidney injury (17.5% vs 20.8%, respectively; relative risk, 0.83 [95% CI, 0.72-0.97],P = .01); however, there was no significant difference between the 2 groups in the loss of kidney function at 1 year (17.1% vs 15.3%, respectively; relative risk, 1.10 [95% CI, 0.95-1.29],P = .23). Results were consistent with multiple alternate continuous and categorical definitions of acute kidney injury or kidney function loss, and in the subgroup with baseline chronic kidney disease. CONCLUSIONS AND RELEVANCE Use of off-pump compared with on-pump CABG surgery reduced the risk of postoperative acute kidney injury, without evidence of better preserved kidney function with off-pump CABG surgery at 1 year. In this setting, an intervention that reduced the risk of mild to moderate acute kidney injury did not alter longer-term kidney function.Journal of the American Medical Association 06/2014; DOI:10.1001/jama.2014.4952
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ABSTRACT: PURPOSE OF REVIEW: Chronic kidney disease (CKD) remains one of the most potent predictors of acute kidney injury (AKI); however, recent epidemiologic studies have demonstrated a complex interplay between these two clinical entities. A growing body of evidence supports a bidirectional relationship: AKI leads to CKD, and the presence of CKD increases the risk of AKI. Additionally, several studies suggest that the presence of underlying CKD does modify the relation between AKI and adverse outcomes. In this article, we will review recent studies supporting the hypothesis that AKI leads to CKD and will explore the role of CKD as an effect modifier for AKI. RECENT FINDINGS: A recent meta-analysis confirms the association between AKI and the development of CKD and end-stage renal disease. Patient survival and renal outcomes after AKI are influenced by the presence of underlying CKD. AKI survivors with complete recovery of renal function remain at elevated risk of developing de-novo CKD, which may influence long-term survival; however, recovery of kidney function after AKI is associated with better long-term survival and renal function. SUMMARY: Recent findings support a strong association between AKI and CKD. There is uncertainty as to whether this relationship is causal. CKD is an effect modifier in AKI.Current opinion in nephrology and hypertension 03/2013; DOI:10.1097/MNH.0b013e32835fe5c5 · 3.96 Impact Factor