Outcomes Among Patients Hospitalized With COVID-19 and Acute Kidney Injury

Abstract

Rationale & objective: Outcomes of patients hospitalized with coronavirus disease 2019 (COVID-19) and acute kidney injury (AKI) are not well understood. The goal of this study was to investigate the survival and kidney outcomes of these patients.

Study design: Retrospective cohort study.

Setting & participants: Patients (aged≥18 years) hospitalized with COVID-19 at 13 hospitals in metropolitan New York between March 1, 2020, and April 27, 2020, followed up until hospital discharge.

Exposure: AKI.

Outcomes: Primary outcome: in-hospital death.

Secondary outcomes: requiring dialysis at discharge, recovery of kidney function.

Analytical approach: Univariable and multivariable time-to-event analysis and logistic regression.

Results: Among 9,657 patients admitted with COVID-19, the AKI incidence rate was 38.4/1,000 patient-days. Incidence rates of in-hospital death among patients without AKI, with AKI not requiring dialysis (AKI stages 1-3), and with AKI receiving dialysis (AKI 3D) were 10.8, 31.1, and 37.5/1,000 patient-days, respectively. Taking those without AKI as the reference group, we observed greater risks for in-hospital death for patients with AKI 1-3 and AKI 3D (HRs of 5.6 [95% CI, 5.0-6.3] and 11.3 [95% CI, 9.6-13.1], respectively). After adjusting for demographics, comorbid conditions, and illness severity, the risk for death remained higher among those with AKI 1-3 (adjusted HR, 3.4 [95% CI, 3.0-3.9]) and AKI 3D (adjusted HR, 6.4 [95% CI, 5.5-7.6]) compared with those without AKI. Among patients with AKI 1-3 who survived, 74.1% achieved kidney recovery by the time of discharge. Among those with AKI 3D who survived, 30.6% remained on dialysis at discharge, and prehospitalization chronic kidney disease was the only independent risk factor associated with needing dialysis at discharge (adjusted OR, 9.3 [95% CI, 2.3-37.8]).

Limitations: Observational retrospective study, limited to the NY metropolitan area during the peak of the COVID-19 pandemic.

Conclusions: AKI in hospitalized patients with COVID-19 was associated with significant risk for death.

Keywords: AKI-on-CKD; COVID-19 outcomes; Coronavirus disease 2019 (COVID-19); acute kidney injury (AKI); acute renal failure (ARF); death; dialysis; hospitalization; in-hospital mortality; kidney replacement therapy (KRT); recovery; renal prognosis; renal recovery; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Graphical abstract

Figure 1

Flow chart of study cohort. Abbreviation: COVID-19, coronavirus disease 2019.

Figure 2

Hospital disposition by status of acute kidney injury (AKI). Of the 9,657 patients in the study cohort, 7.3% of those without AKI died, whereas the proportion of patients who died was higher among those with AKI stages 1 - 3 not receiving dialysis (AKI 1-3) (46.4%) and AKI receiving dialysis (AKI 3D) (79.3%). Among the entire cohort, only 0.9% of patients remained hospitalized.

Figure 3

Flow chart of survival and kidney outcomes for patients with acute kidney injury (AKI) stages 1 to 3 but not receiving dialysis (AKI 1-3) and AKI stage 3 receiving dialysis (AKI 3D). Of 3,854 patients with AKI (39.9% of initial cohort [n = 9,657]), most (83.4%) had AKI 1-3, while 16.6% had AKI 3D. In the AKI 1-3 group, 46.4% died and 51.7% survived, of whom 74.1% had kidney recovery. Among AKI 3D, 79.3% died and 17% survived. Of the survivors, 66.7% had kidney recovery and 33.3% did not. Most (92%) of those without kidney recovery continued to require dialysis at discharge. ^∗Kidney recovery defined as decline of at least 33% from peak serum creatinine level and not receiving dialysis at the time of discharge.

Figure 4

Admission, peak, and discharge serum creatinine levels among patients discharged alive, by stages of acute kidney injury (AKI). Across all stages of AKI, median serum creatinine level on discharge was lower than the median serum creatinine level at hospital admission or the median peak serum creatinine level. AKI stage 3 denotes only those who did not receive dialysis.