Short and Long-term Recovery after Moderate/Severe Acute Kidney Injury in patients with and without COVID-19

Introduction: Severe AKI is strongly associated with poor outcomes in COVID-19, but data on renal recovery is lacking. Methods: We retrospectively analyzed these associations in 3,299 hospitalized patients (1,338 with COVID-19 and 1,961 with acute respiratory illness but tested negative for COVID-19). Uni- and multi-variable analyses were used to study mortality and recovery after KDIGO Stage 2&3 AKI and Machine Learning (ML) for predicting AKI and recovery using admission data. Long-term renal function and other outcomes were studied in a sub-group of AKI-2/3 survivors. Results: Among the 172 COVID-19 negative patients with AKI-2/3, 74.4% had partial & 44.2% complete renal recovery, while 11.6% died. Among 255 COVID-19 positive patients with AKI-2/3, lower recovery and higher mortality were noted (50.6% partial, 24.7% complete renal recovery, 23.9% died). On multivariable analysis, ICU admission and ARDS were associated with non-recovery, and recovery was significantly associated with survival in COVID-19 positive patients. With ML, we were able to predict recovery from COVID-19-associated AKI-2/3 with an average precision of 0.62 and the strongest predictors of recovery were initial arterial paO2 & CO2, SCr, K, lymphocyte count, & CPK. At 12 months follow-up, among 52 survivors with AKI-2/3, 25.7% COVID-19 positive and 23.5% COVID-19 negative had incident or progressive CKD. Conclusions: Recovery from COVID-19-associated moderate/severe AKI, can be predicted using admission data and is associated with severity of respiratory disease and in-hospital death. The risk of CKD might be similar between COVID-19 positive and negative patients.