<b><i>Introduction:</i></b> Acute kidney injury (AKI) is strongly associated with poor outcomes in hospitalized patients with coronavirus disease 2019 (COVID-19), but data on the association of proteinuria and hematuria are limited to non-US populations. In addition, admission and in-hospital measures for kidney abnormalities have not been studied separately. <b><i>Methods:</i></b> This retrospective cohort study aimed to analyze these associations in 321 patients sequentially admitted between March 7, 2020 and April 1, 2020 at Stony Brook University Medical Center, New York. We investigated the association of proteinuria, hematuria, and AKI with outcomes of inflammation, intensive care unit (ICU) admission, invasive mechanical ventilation (IMV), and in-hospital death. We used ANOVA, <i>t</i> test, χ² test, and Fisher’s exact test for bivariate analyses and logistic regression for multivariable analysis. <b><i>Results:</i></b> Three hundred patients met the inclusion criteria for the study cohort. Multivariable analysis demonstrated that admission proteinuria was significantly associated with risk of in-hospital AKI (OR 4.71, 95% CI 1.28–17.38), while admission hematuria was associated with ICU admission (OR 4.56, 95% CI 1.12–18.64), IMV (OR 8.79, 95% CI 2.08–37.00), and death (OR 18.03, 95% CI 2.84–114.57). During hospitalization, de novo proteinuria was significantly associated with increased risk of death (OR 8.94, 95% CI 1.19–114.4, <i>p</i> = 0.04). In-hospital AKI increased (OR 27.14, 95% CI 4.44–240.17) while recovery from in-hospital AKI decreased the risk of death (OR 0.001, 95% CI 0.001–0.06). <b><i>Conclusion:</i></b> Proteinuria and hematuria both at the time of admission and during hospitalization are associated with adverse clinical outcomes in hospitalized patients with 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.