LAUSR

Introduction Acute kidney injury (AKI) is a common complication in patients with severe COVID-19. We sought to compare the AKI incidence and outcomes among patients hospitalized with COVID-19 and with influenza. Methods Retrospective cohort study of patients with COVID-19 hospitalized between March–May 2020 and historical controls hospitalized with influenza A or B between January 2017 and December 2019 within a large healthcare system. Cox proportional hazards models were used to compare the risk of AKI during hospitalization. Secondary outcomes included AKI recovery, mortality, new-onset chronic kidney disease (CKD) and ≥ 25% estimated glomerular filtration rate (eGFR) decline. Results A total of 2425 patients were included; 1091 (45%) had COVID-19 and 1334 (55%) had influenza. Overall AKI rate was 23% and 13% in patients with COVID-19 and influenza, respectively. Compared to influenza, hospitalized patients with COVID-19 had an increased risk of developing AKI (adjusted hazard ratio, aHR 1.58, 95% CI 1.29–1.94). Patients with AKI were more likely to die during hospital when infected with COVID-19 vs. influenza (aHR 3.55, 95% CI 2.11–5.97). Among patients surviving to hospital discharge, the rate of AKI recovery was lower in patients with COVID-19 (aHR 0.47, 95% CI 0.36–0.62); however, among patients followed for ≥ 90 days, new-onset CKD (aHR 1.24, 95% CI 0.86–1.78) and ≥ 25% eGFR decline at last follow-up (aHR 1.36, 95% CI 0.97–1.90) were not significantly different between the cohorts. Conclusion AKI and mortality rates are significantly higher in COVID-19 than influenza; however, kidney recovery among long-term survivors appears to be similar.