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Acute kidney injury (AKI) increases morbidity, mortality, and health expenses. Its incidence is higher in critically ill patients. During the SARS-COV-2 pandemic, a higher incidence of AKI and requirement of renal replacement therapy (RRT) was evidenced, with mortality higher than 80%, and is considered in some centers as a criterion for palliative management. Previous studies have compared the incidence and risk factors for AKI and RRT between COVID-19 and other viral infections. Management was extrapolated from septic AKI; however, the pathophysiology, clinical course, and outcomes appear to be different. This study aimed to compare in-hospital mortality in severe COVID-19-associated AKI compared to non-COVID-19 S-AKI.
A parallel retrospective cohort-type analytical observational study of hospitalized patients with COVID-19-associated AKI and non-COVID-19 S-AKI who require RRT was performed from November 2016 to December 2022, in 4 fourth-level institutions in Bogota, Colombia. In patients with AKI associated COVID-19, bacterial or fungal co-infection or use of antibiotics was excluded. It was approved by the ethics committee. Data were extracted from medical records and recorded in RedCap® and analysis was performed in R version 4.3.1. Descriptive statistics were used for baseline demographic and clinical characteristics, laboratory data, multi-organ support, and severity; crude mortality was calculated, and multivariate analysis was performed to determine independent predictors of in-hospital mortality.
Data were obtained from 418 patients, 176 with COVID-19-associated AKI and 242 with non-COVID-19 S-AKI, all requiring RRT. Crude mortality during hospitalization was 81.2% in COVID-19-associated AKI and 61.2% in the S-AKI control group. After adjusting for age, baseline serum creatinine, invasive mechanical ventilation, vasopressor, etiology, volume overload, non-renal SOFA, and comorbidities, the risk of in-hospital mortality was significantly higher in patients with COVID-19-associated AKI (OR 8.68, 95% CI 2.12-35.4, P=0.003). Other factors associated with mortality were invasive ventilator support (OR 11.73, 95% CI 1.85-74.35, P=0.009) and age (OR 1.05, 95% CI 1.00-1.10, P=0.02). Protective factors were urinary volume prior to renal replacement therapy (OR 0.99, 95% CI 0.99-1.00, p=0.026) and history of solid neoplasm (OR 0.10, 95% CI 0.021-0.532, p=0.006). Baseline renal function, comorbidities, water balance, non-renal SOFA, vasopressor use, and ICU beds were not associated with primary outcomes. CRRT was the most frequently prescribed modality (62.92%), anuria as the first indication for the initiation of RRT. Despite the high mortality, the renal recovery rate in patients with AKI associated with COVID-19 is higher compared to septic AKI (36.7% vs 17%, p<0.001), without an increase in the complications of RRT or the catheter.
COVID-19 is an independent risk factor for mortality in severe AKI requiring RRT, adjusted for clinical characteristics, laboratory, comorbidities, ICU occupancy and multi-organ support. The risk of death associated with severe AKI with RRT is higher in patients with COVID-19 compared to S-AKI and is associated with higher ICU admission, requirement of mechanical ventilation, use of vasopressor and with better renal recovery rates.