Risk factors for RRT and mortality in patients with COVID-19-related AKI in São Paulo, Brazil

Background: In COVID-19, as in SARS, the degree of kidney injury can have major implications for the clinical outcomes. Early reports indicate that, among patients with COVID-19, AKI is common and is associated with worse outcomes. However, COVID-19-related AKI among ICU patients in Brazil has not been well described. Methods: This was a retrospective observational study of the electronic health records of patients with COVID-19-related AKI admitted to the Hospital das Clinicas in the city of Sao Paulo, Brazil, between March and August of 2020. We applied only KDIGO criteria 2 and 3. We used logistic regression to analyze risk factors for the composite outcome of mortality or RRT. Results: Among the 694 patients with COVID-19-related AKI, the mean age was 63 years and mortality was 66.4%;41% needed vasoactive drugs, 66% needed mechanical ventilation, and 72% needed dialysis. Univariate analysis showed the following risk factors for mortality and RRT at admission: male sex;diabetes;CKD;vasoactive drug use;mechanical ventilation;acidemia;elevated lactate, magnesium, potassium, creatinine, C-reactive protein, creatine phosphokinase, total bilirrubin;proteinuria;hematuria;and increased fractional excretion of potassium (n=98) and sodium (n=110). The factors that remained significant in the multivariate analysis were male sex, vasoactive drug use, serum magnesium >2.5 mg/dL and oliguria (24-h urine output <500 mL). Conclusions: In ICU patients with COVID-19-related AKI, in Brazil and elsewhere, in-hospital mortality is high. The exact mechanism by which hypermagnesemia increases mortality in such patients merits further study.