Postoperative acute kidney injury is associated with persistent renal dysfunction: a multicentre propensity-matched cohort study.

Background: The risk of developing a persistent reduction in renal function after postoperative acute kidney injury (pAKI) is not well established. The goal of this investigation was to evaluate whether patients who develop pAKI have a greater decline in long-term renal function than patients who do not. Methods: In this multicentre retrospective propensity-matched study, anaesthesia data warehouses at three tertiary care hospitals were queried. Adult patients undergoing surgery with available preoperative and postoperative creatinine results and without baseline haemodialysis requirements were included. Patients were stratified by occurrence of pAKI as defined by the Acute Kidney Injury Network classification. The primary outcome was a decline in follow-up glomerular filtration rate (GFR) of 40% relative to baseline, based on follow-up outpatient visits from 0 to 36 months after hospital discharge. A propensity score-matched sample was used in Kaplan-Meier analysis and a piecewise Cox model to compare the time to reach a 40% decline in GFR for patients with and without pAKI. Results: In 95 213 patients, the rate of pAKI ranged from 9.9% to 13.7%. In the piecewise Cox model, pAKI was associated with a significantly increased hazard of a 40% decline in GFR. The common-effect hazard ratio was 13.35 (95% confidence interval [CI] 10.79-16.51, Conclusions: pAKI is associated with a significantly increased hazard of a 40% decline in GFR up to 36 months after surgery across three institutions.