Am J Kidney Dis. 2021 Jan 7:S0272-6386(21)00003-2. doi: 10.1053/j.ajkd.2020.12.007. Online ahead of print.
RATIONALE AND OBJECTIVE: While COVID-19 infection has been associated with acute kidney injury (AKI), it is unclear whether this association is independent of traditional risk factors such as hypotension, nephrotoxin exposure, and inflammation. We tested the independent association of COVID-19 with AKI.
STUDY DESIGN: Multicenter, observational, cohort study.
SETTING AND PARTICIPANTS: Patients admitted to one of six hospitals within the Yale-New Haven Health System between 3/10/2020 and 8/31/2020 and tested for SARS-CoV-2 via nasopharyngeal PCR test.
EXPOSURE: Positive test for SARS-CoV-2.
OUTCOME: AKI by Kidney Disease: Improving Global Outcomes criteria.
ANALYTIC APPROACH: Evaluated the association of COVID-19 with AKI after controlling for time-invariant factors at admission (e.g., demographics, comorbidities) and time-varying factors updated continuously during hospitalization (e.g., vital signs, medications, laboratory results, respiratory failure) using time-updated Cox proportional hazard models.
RESULTS: Of the 22,122 patients hospitalized between, 2,600 tested positive and 19,522 tested negative for SARS-CoV-2. Compared to patients who tested negative, patients with COVID-19 had more AKI [30.6% vs. 18.2%, absolute risk difference 12.5 (95% CI, 10.6, 14.3)%] and dialysis-requiring AKI (8.5% vs. 3.6%) and lower recovery from AKI (58% vs. 69.8%]. Compared to patients who tested negative, patients with COVID-19 had higher inflammatory markers (C-reactive protein, ferritin), and greater use of vasopressors and diuretics. Compared to patients who tested negative, patients with COVID-19 had higher rate of AKI in univariable analysis (HR, 1.84 [1.73, 1.95]). In fully adjusted model controlling for demographics, comorbidities, vital signs, medications, and laboratory results, COVID-19 remained associated with a high rate of AKI (adjusted HR, 1.40 [1.29-1.53]).
LIMITATIONS: Possibility of residual confounding.
CONCLUSIONS: COVID-19 is associated with high rates of AKI not fully explained by adjustment for known risk factors. This suggests the presence of mechanisms of AKI not accounted for in this analysis, which may include a direct effect of COVID-19 on the kidney or other unmeasured mediators. Future studies should evaluate the possible unique pathways by which COVID-19 may cause AKI.