Angiotensin-converting enzyme inhibitor usage and acute kidney injury: a secondary analysis of RENAL study outcomes

Aim: Acute kidney injury (AKI) is associated with increased mortality. While angiotensin-converting enzyme inhibitors (ACEI) are known to slow progression of chronic kidney disease, their role in AKI remains unclear. Methods: The Randomised Evaluation of Normal vs. Augmented Level Replacement Therapy (RENAL) study data were analysed according to ACEI use over time. The primary outcome was all-cause mortality at 90 days following randomisation. Analyses used a multivariate Cox model adjusted for either baseline or for time-dependent covariates, and a sensitivity analysis of patients surviving to at least the median time to ACEI initiation. Results: Of the 1463 participants with available data on ACE inhibitors usage, 142 (9.7%) received ACEI at least once during study data collection. Participants treated with ACEI were older (P = 0.02) and had less sepsis at baseline (P < 0.001). ACEI use was significantly associated with lower mortality at 90 days (HR 0.46, 95% CI 0.30-0.71, P < 0.001), and an increase in renal replacement therapy-free days (P < 0.001), intensive care unit-free days (P < 0.001) and hospital free-days (P < 0.001) after adjusting for baseline covariates. Using the time-dependent analysis, however, the effect of ACEI administration was not significant (HR 0.78, 95% CI 0.51-1.21, P = 0.3). The sensitivity analysis in day 8 survivors produced similar results. Conclusion: In the RENAL study cohort, the use of ACEI during the study was not common and, after adjustment for time-dependent covariates, was not significantly associated with reductions in mortality. Further assessment of the effect of ACEI use in AKI patients is needed.