Recovery of kidney function after acute kidney disease-a multi-cohort analysis.

Abstract

There are no consensus definitions for evaluating kidney function recovery after acute kidney injury (AKI) and acute kidney disease (AKD), nor is it clear how recovery varies across populations and clinical subsets. We present a federated analysis of four population-based cohorts from Canada, Denmark and Scotland, 2011-18. We identified incident AKD defined by serum creatinine changes within 48h, 7days and 90days based on KDIGO AKI and AKD criteria. Separately, we applied changes up to 365days to address widely used e-alert implementations that extend beyond the KDIGO AKI and AKD timeframes. Kidney recovery was based on resolution of AKD and a subsequent creatinine measurement below 1.2× baseline. We evaluated transitions between non-recovery, recovery and death up to 1year; within age, sex and comorbidity subgroups; between subset AKD definitions; and across cohorts. There were 464868 incident cases, median age 67-75years. At 1year, results were consistent across cohorts, with pooled mortalities for creatinine changes within 48h, 7days, 90days and 365days (and 95% confidence interval) of 40% (34%-45%), 40% (34%-46%), 37% (31%-42%) and 22% (16%-29%) respectively, and non-recovery of kidney function of 19% (15%-23%), 30% (24%-35%), 25% (21%-29%) and 37% (30%-43%), respectively. Recovery by 14 and 90days was frequently not sustained at 1year. Older males and those with heart failure or cancer were more likely to die than to experience sustained non-recovery, whereas the converse was true for younger females and those with diabetes. Consistently across multiple cohorts, based on 1-year mortality and non-recovery, KDIGO AKD (up to 90days) is at least prognostically similar to KDIGO AKI (7days), and covers more people. Outcomes associated with AKD vary by age, sex and comorbidities such that older males are more likely to die, and younger females are less likely to recover.