Kidney Recovery and Death in Critically Ill Patients With COVID-19-Associated Acute Kidney Injury Treated With Dialysis: The STOP-COVID Cohort Study

Abstract

Rationale & objective: Acute kidney injury treated with kidney replacement therapy (AKI-KRT) occurs frequently in critically ill patients with coronavirus disease 2019 (COVID-19). We examined the clinical factors that determine kidney recovery in this population.

Study design: Multicenter cohort study.

Setting & participants: 4,221 adults not receiving KRT who were admitted to intensive care units at 68 US hospitals with COVID-19 from March 1 to June 22, 2020 (the "ICU cohort"). Among these, 876 developed AKI-KRT after admission to the ICU (the "AKI-KRT subcohort").

Exposure: The ICU cohort was analyzed using AKI severity as the exposure. For the AKI-KRT subcohort, exposures included demographics, comorbidities, initial mode of KRT, and markers of illness severity at the time of KRT initiation.

Outcome: The outcome for the ICU cohort was estimated glomerular filtration rate (eGFR) at hospital discharge. A 3-level outcome (death, kidney nonrecovery, and kidney recovery at discharge) was analyzed for the AKI-KRT subcohort.

Analytical approach: The ICU cohort was characterized using descriptive analyses. The AKI-KRT subcohort was characterized with both descriptive analyses and multinomial logistic regression to assess factors associated with kidney nonrecovery while accounting for death.

Results: Among a total of 4,221 patients in the ICU cohort, 2,361 (56%) developed AKI, including 876 (21%) who received KRT. More severe AKI was associated with higher mortality. Among survivors, more severe AKI was associated with an increased rate of kidney nonrecovery and lower kidney function at discharge. Among the 876 patients with AKI-KRT, 588 (67%) died, 95 (11%) had kidney nonrecovery, and 193 (22%) had kidney recovery by the time of discharge. The odds of kidney nonrecovery was greater for lower baseline eGFR, with ORs of 2.09 (95% CI, 1.09-4.04), 4.27 (95% CI, 1.99-9.17), and 8.69 (95% CI, 3.07-24.55) for baseline eGFR 31-60, 16-30, ≤15 mL/min/1.73 m², respectively, compared with eGFR > 60 mL/min/1.73 m². Oliguria at the time of KRT initiation was also associated with nonrecovery (ORs of 2.10 [95% CI, 1.14-3.88] and 4.02 [95% CI, 1.72-9.39] for patients with 50-499 and <50 mL/d of urine, respectively, compared to ≥500 mL/d of urine).

Limitations: Later recovery events may not have been captured due to lack of postdischarge follow-up.

Conclusions: Lower baseline eGFR and reduced urine output at the time of KRT initiation are each strongly and independently associated with kidney nonrecovery among critically ill patients with COVID-19.

Keywords: Acute kidney injury (AKI); chronic kidney disease (CKD); coronavirus disease 2019 (COVID-19); critical care; dialysis; estimated glomerular filtration rate (eGFR); oligoanuria; prognostication; renal function; renal recovery; urine output.

Graphical abstract

Figure 1

Flow diagram of the study population. Abbreviations: AKI, acute kidney injury; ESKD, end-stage kidney disease; ICU, intensive care unit; KRT, kidney replacement therapy; Scr, serum creatinine; STOP-COVID, Study of the Treatment and Outcomes in Critically Ill Patients With COVID-19.

Figure 2

Outcomes of the ICU cohort. AKI stage 1 defined as peak Scr is 1.5-1.9 times baseline Scr; AKI stage 2, peak Scr is 2.0-2.9 times baseline; AKI stage 3 without KRT, peak Scr is ≥3.0 times baseline. Abbreviations: AKI, acute kidney injury; ICU, intensive care unit; KRT, kidney replacement therapy; Scr, serum creatinine.

Figure 3

Kidney outcomes of the ICU cohort, survivors only. AKI stage 1 defined as peak serum Cr is 1.5-1.9 times baseline serum Cr; AKI stage 2, peak serum Cr is 2.0-2.9 times baseline; AKI stage 3 without KRT, peak serum Cr is ≥3.0 times baseline. For clarity, bars less than 4% are unlabeled. Abbreviations: AKI, acute kidney injury; Cr, creatinine; ICU, intensive care unit; KRT, kidney replacement therapy.

Figure 4

Multivariable multinomial regression, using recovery as the reference outcome. Abbreviations: CKRT, continuous kidney replacement therapy; eGFR, estimated glomerular filtration rate; iHD, intermittent hemodialysis; KRT, kidney replacement therapy; PD, peritoneal dialysis.

Figure 5

Percent of survivors with kidney nonrecovery at discharge, by baseline eGFR and urine output on KRT day 1. Each bar shows the percent with kidney nonrecovery at discharge, out of the survivors. For example, 92 patients with a baseline eGFR > 30 mL/min/1.73 m² and urine output of ≥500 mL/d on KRT day 1 survived to discharge; 18 (20%) of these patients had kidney nonrecovery at discharge. Abbreviations: eGFR, estimated glomerular filtration rate; KRT, kidney replacement therapy.

Figure 6

Outcome of kidney nonrecovery (vs recovery) at hospital discharge, among survivors. Abbreviations: CKRT, continuous kidney replacement therapy; eGFR, estimated glomerular filtration rate; iHD, intermittent hemodialysis; KRT, kidney replacement therapy; PD, peritoneal dialysis.

Figure 7

Kidney function at discharge among AKI-KRT patients, survivors only. Abbreviations: AKI-KRT, acute kidney injury treated with kidney replacement therapy; eGFR, estimated glomerular filtration rate.