Background

Acute kidney injury (AKI) is common in coronavirus disease-2019 (COVID-19) and the severity of AKI is linked to adverse outcomes. In this study, we investigated the factors asso- ciated with in-hospital outcomes among hospitalized patients with COVID-19 and AKI.

Methods

In this multicenter retrospective observational study, we evaluated the characteristics and in-hospital renal and patient outcomes of 578 patients with confirmed COVID-19 and AKI. Data were collected from 34 hospitals in Turkey from March 11 to June 30, 2020. AKI defini- tion and staging were based on the Kidney Disease Improving Global Outcomes criteria. Patients with end-stage kidney disease or with a kidney transplant were excluded. Renal outcomes were identified only in discharged patients.

Results

The median age of the patients was 69 years, and 60.9% were males. The most frequent comorbid conditions were hypertension (70.5%), diabetes mellitus (43.8%), and chronic kid- ney disease (CKD) (37.6%). The proportions of AKI stages 1, 2, and 3 were 54.0%, 24.7%, and 21.3%, respectively. 291 patients (50.3%) were admitted to the intensive care unit. Renal improvement was complete in 81.7% and partial in 17.2% of the patients who were discharged. Renal outcomes were worse in patients with AKI stage 3 or baseline CKD. The overall in-hospital mortality in patients with AKI was 38.9%. In-hospital mortality rate was not different in patients with preexisting non-dialysis CKD compared to patients without CKD (34.4 versus 34.0%, p = 0.924). By multivariate Cox regression analysis, age (hazard ratio [HR] [95% confidence interval (95%CI)]: 1.01 [1.0–1.03], p = 0.035], male gender (HR [95% CI]: 1.47 [1.04–2.09], p = 0.029), diabetes mellitus (HR [95%CI]: 1.51 [1.06–2.17], p = 0.022) and cerebrovascular disease (HR [95%CI]: 1.82 [1.08–3.07], p = 0.023), serum lac- tate dehydrogenase (greater than two-fold increase) (HR [95%CI]: 1.55 [1.05–2.30], p = 0.027) and AKI stage 2 (HR [95%CI]: 1.98 [1.25–3.14], p = 0.003) and stage 3 (HR [95%CI]: 2.25 [1.44–3.51], p = 0.0001) were independent predictors of in-hospital mortality.

Conclusions

Advanced-stage AKI is associated with extremely high mortality among hospitalized COVID-19 patients. Age, male gender, comorbidities, which are risk factors for mortality in patients with COVID-19 in the general population, are also related to in-hospital mortality in patients with AKI. However, preexisting non-dialysis CKD did not increase in-hospital mor- tality rate among AKI patients. Renal problems continue in a significant portion of the patients who were discharged.