AKI in Hospitalized Patients with COVID-19 and Seasonal Influenza: A Comparative Analysis.

Background: Coronavirus disease 2019 (COVID-19) is often compared with seasonal influenza and the two diseases have similarities, including the risk of systemic manifestations such as AKI. The aim of this study was to perform a comparative analysis of the prevalence, risk factors, and outcomes of AKI in patients who were hospitalized with COVID-19 and influenza.

Methods: Retrospective cohort study of patients who were hospitalized with COVID-19 (=325) or seasonal influenza (=433). AKI was defined by Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Baseline characteristics and hospitalization data were collected, and multivariable analysis was performed to determine the independent predictors for AKI.

Results: AKI occurred in 33% of COVID-19 hospitalizations (COV-AKI) and 33% of influenza hospitalizations (FLU-AKI). After adjusting for age, sex, and comorbidity count, the risk of stage 3 AKI was significantly higher in COV-AKI (OR, 3.46; 95% CI, 1.63 to 7.37). Pre-existing CKD was associated with a six- to seven-fold increased likelihood for FLU-AKI and COV-AKI. Mechanical ventilation was associated with a higher likelihood of developing AKI in the COVID-19 cohort (OR, 5.85; 95% CI, 2.30 to 15.63). Black race, after adjustment for comorbidities, was an independent risk for COV-AKI.

Conclusions: Pre-existing CKD was a major risk factor for AKI in both cohorts. Black race (independent of comorbidities) and mechanical ventilation were associated with a higher risk of developing COV-AKI, which is characterized by a higher burden of stage 3 AKI and overall poorer prognosis.