Analysis of autopsy tissues obtained from patients who died from COVID-19 showed kidney tropism for SARS-COV-2, with COVID-19-related renal dysfunction representing an overlooked problem even in patients lacking previous history of chronic kidney disease. This study aimed to corroborate in a substantial sample of consecutive acutely ill COVID-19 hospitalized patients the efficacy of estimated GFR (eGFR), assessed at hospital admission, to identify acute renal function derangement and the predictive role of its association with in-hospital death and need for mechanical ventilation and admission to intensive care unit (ICU).

We retrospectively analyzed charts of 764 patients firstly admitted to regular medical wards (Division of Internal Medicine) for symptomatic COVID-19 between March 6th and May 30th, 2020 and between October 1st, 2020 and March 15th, 2021. eGFR values were calculated with the 2021 CKD-EPI formula and assessed at hospital admission and discharge. Baseline creatinine and GFR values were assessed by chart review of patients’ medical records from hospital admittance data in the previous year. The primary outcome was in-hospital mortality, while ARDS development and need for non-invasive ventilation (NIV) and invasive mechanical ventilation (IMV) were the secondary outcomes.

SARS-COV-2 infection was diagnosed in 764 patients admitted with COVID-19 symptoms. A total of 682 patients (age range 23–100 years) were considered for statistical analysis, 310 needed mechanical ventilation and 137 died. An eGFR value <60 mL/min/1.73 m² was found in 208 patients, 181 met KDIGO AKI criteria; eGFR values at hospital admission were significantly lower with respect to both hospital discharge and baseline values (p < 0.001). In multivariate analysis, an eGFR value <60 mL/min/1.73 m² was significantly associated with in-hospital mortality (OR 2.6, 1.7–4.8, p = 0.003); no association was found with both ARDS and need for mechanical ventilation. eGFR was non-inferior to both IL-6 serum levels and CALL Score in predicting in-hospital death (AUC 0.71, 0.68–0.74, p = 0.55).

eGFR calculated at hospital admission correlated well with COVID-19-related kidney injury and eGFR values < 60 mL/min/1,73 m² were independently associated with in-hospital mortality, but not with both ARDS or need for mechanical ventilation.