COVID-19-Associated Acute Kidney Injury and Longitudinal Kidney Outcomes

Abstract

Importance: COVID-19 infection is associated with a high incidence of acute kidney injury (AKI). Although rapid kidney function decline has been reported in the first few months after COVID-19-associated AKI (COVID-AKI), the longer-term association of COVID-AKI with kidney function remains unknown.

Objective: To assess long-term kidney outcomes of patients who had COVID-19-associated AKI.

Design, setting, and participants: This was a retrospective longitudinal multicenter cohort study conducted in a large hospital system using electronic health records data on adult hospitalized patients with AKI and COVID-19 or other illnesses. Included patients were hospitalized during the COVID-19 pandemic (March 2020-June 2022), were screened for SARS-CoV-2, had AKI, and survived to discharge, or had been hospitalized during the 5 years before the pandemic (October 2016-January 2020), had a positive influenza A or B test result, had AKI, and survived to discharge. Patients were followed up for a maximum of 2 years after hospital discharge. Data analyses were performed from December 2022 to November 2023.

Exposure: COVID-19 and influenza.

Main outcomes and measures: The primary outcome was major adverse kidney events (MAKE), defined as a composite of mortality and worsened kidney function (estimated glomerular filtration rate [eGFR] decline by ≥25% from discharge eGFR or kidney failure requiring dialysis). Multivariable time-to-event analyses were performed to compare MAKE between individuals with COVID-AKI and those who had AKI associated with other illnesses hospitalized during the same period. For further comparison, this outcome was assessed for a historic cohort of patients with influenza-associated AKI.

Results: The study cohort included 9624 hospitalized patients (mean [SD] age, 69.0 [15.7] years; 4955 [51.5%] females) with AKI, including 987 patients with COVID-AKI, 276 with influenza-associated AKI, and 8361 with AKI associated with other illnesses (other-AKI). Compared with the other 2 groups, patients with COVID-19-associated AKI were slightly younger in age, had a higher baseline eGFR, worse baseline comorbidity scores, higher markers of illness severity, and longer hospital stay. Compared with the other-AKI group, the COVID-AKI group had lower MAKE (adjusted hazard ratio [aHR], 0.67; 95% CI, 0.59-0.75) due to lower all-cause mortality (aHR, 0.31; 95% CI, 0.24-0.39) and lower rates of worsened kidney function (aHR, 0.78; 95% CI, 0.69-0.88).

Conclusions and relevance: The findings of this multicenter cohort study indicate that survivors of hospitalization with COVID-AKI experience lower rates of MAKE, long-term kidney function decline, and mortality compared with patients with AKI associated with other illnesses.

Figure 1.. Survival Curves of Postdischarge Events With Maximum 2 Years of Follow-Up

Unadjusted Kaplan-Meier curves for (A) time-to-major adverse kidney events, a composite of death or worsened kidney function; (B) time to worsened kidney function, defined as eGFR decline to ≥25% from discharge eGFR or diagnosis of ESKD. Patients were censored at last follow-up eGFR up to 2 years from discharge; (C) Survival. Patients with no death date were considered alive for the duration of 2 years or until the date of data lock, whichever came first. AKI indicates acute kidney injury; eGFR, estimated glomerular filtration rate; ESKD, end-stage kidney disease; and MAKE, major adverse kidney events.

Figure 2.. Subgroup Analyses of MAKE Comparing COVID-19 AKI to Other AKI, and COVID-19 AKI to Influenza AKI

AKI indicates acute kidney injury; CAD, coronary artery disease; CKD, chronic kidney disease; DM, diabetes; HF, heart failure; HR, hazard ratio; HTN, hypertension; MAKE, major adverse kidney events; and NA, not applicable.