Background: Although diffuse alveolar damage and respiratory failure are the key features of coronavirus disease 2019 (COVID-19), the involvement of other organs such as the kidney has also been reported. The reports of the incidence of acute kidney injury (AKI) in COVID-19 patients vary widely. In this study, we report our unique experience with AKI in COVID-19 patients in a low socioeconomic and predominantly ethnic minority group and provide its incidence, risk factors, and prognosis to expand the current understanding of this complication.

Methods: In this single-center, retrospective cohort study, we analyzed the data of 469 COVID-19 patients admitted to the Brookdale University Hospital in Brooklyn, NY, from March 18 through April 23, 2020. Information regarding demographics, comorbidities, medications, clinical and laboratory data, and outcomes was collected from the electronic medical records. Both univariate and multivariate analyses were performed to determine the association of AKI with in-hospital mortality.

Results: The median age was 66 years (interquartile range [IQR] 25-75; range 19-101 years), and 268 (57.14%) patients were male. Estimated glomerular filtration rate (eGFR) as determined by the Modification of Diet in Renal Disease Study Equation was low (<60 mL/min/1.73 m2) in 207 (44.1%) patients. During hospitalization, 128 (27.3%) patients developed AKI, and the incidence was significantly higher in those patients presenting with a low eGFR (N = 81, 39.1%; p < 0.001). Male sex, hypertension, the use of angiotensin-converting enzyme inhibitors and non-steroidal anti-inflammatories, hemodynamic instability, mechanical ventilation, acute respiratory distress syndrome, and admission elevated ferritin, creatinine kinase, brain natriuretic peptide, and troponin 1 were identified as the risk factors for in-hospital AKI. Ninety-seven (28.45%) patients died in the non-AKI group versus 91 (71.1%) in the AKI group (p < 0.001). The Cox proportional hazard model after adjusting for age, gender, comorbidities, hemodynamic status, and PF ratio (arterial oxygen partial pressure [PaO2]/fractional inspired oxygen [FiO2]) determined that on admission, an elevated blood urea nitrogen (hazard ratio [HR]: 1.75; 95% confidence interval [CI] 1.23-2.48), a low eGFR (HR 1.43; CI 1.1-2.03), AKI stage 1 (HR 1.14; CI 0.64-2.03), AKI stage 2 (HR 1.86; CI 1.03-3.56), and AKI stage 3 (HR 2.1; CI 1.3-2.81) were independent risk factors for in-hospital mortality. Renal replacement therapy (RRT) did not improve survival in stage III AKI.

Conclusion: AKI in our hospitalized COVID-19 patients was common and carried a high mortality, especially in patients with AKI stage 3. RRT did not improve survival. Policy changes and planning for this high incidence of AKI in COVID-19 patients and its associated high mortality are necessary at the local and national levels.