BACKGROUND: Research regarding COVID-19 and acute kidney injury (AKI) in older adults is scarce . We evaluated risk factors and outcomes of AKI in hospitalized older adults with and without COVID-19 .

METHODS: Observational study of patients admitted to two geriatric clinics in Stockholm from March 1st to June 15th , 2020 . The difference in incidence, risk factors and adverse outcomes for AKI between patients with or without COVID-19 were examined . Odds ratios (OR) for the risk of AKI and in-hospital death were obtained from logistic regression .

RESULTS: Three hundred-sixteen older patients were hospitalized for COVID-19 and 876 patients for non-COVID-19 diagnoses . AKI occurred in 92 (29 %) patients with COVID-19 vs. 159 (18 %) without COVID-19 . The odds for developing AKI were higher in patients with COVID-19 (adjusted OR , 1.70; 95% confidence interval [CI] 1.04-2.76), low baseline kidney function as depicted by estimated glomerular filtration rate (eGFR) [4.19 (2.48-7.05), for eGFR 30 to <60 mL/min, and 20.3 (9.95-41.3) for eGFR <30 mL/min], and higher C reactive protein (CRP) (OR 1.81 (1.11-2.95) in patients with initial CRP> 10 mg/L). Compared to patients without COVID-19 and without AKI, the risk of in-hospital death was highest in patients with COVID-19 and AKI [OR 80.3 , 95% CI (27.3-235.6) ], followed by COVID-19 without AKI [16.3 (6.28-42.4) ], and by patients without COVID-19 and with AKI [10.2 (3.66-28.2) ].

CONCLUSIONS: Geriatric patients hospitalized with COVID-19 had a higher incidence of AKI compared to patients hospitalized for other diagnoses . COVID-19 and reduced baseline kidney function were risk factors for developing AKI . AKI and COVID-19 were associated with in-hospital death.