Characteristics and Outcomes of Individuals With Pre-existing Kidney Disease and COVID-19 Admitted to Intensive Care Units in the United States

Abstract

Rationale & objective: Underlying kidney disease is an emerging risk factor for more severe coronavirus disease 2019 (COVID-19) illness. We examined the clinical courses of critically ill COVID-19 patients with and without pre-existing chronic kidney disease (CKD) and investigated the association between the degree of underlying kidney disease and in-hospital outcomes.

Study design: Retrospective cohort study.

Settings & participants: 4,264 critically ill patients with COVID-19 (143 patients with pre-existing kidney failure receiving maintenance dialysis; 521 patients with pre-existing non-dialysis-dependent CKD; and 3,600 patients without pre-existing CKD) admitted to intensive care units (ICUs) at 68 hospitals across the United States.

Predictor(s): Presence (vs absence) of pre-existing kidney disease.

Outcome(s): In-hospital mortality (primary); respiratory failure, shock, ventricular arrhythmia/cardiac arrest, thromboembolic events, major bleeds, and acute liver injury (secondary).

Analytical approach: We used standardized differences to compare patient characteristics (values>0.10 indicate a meaningful difference between groups) and multivariable-adjusted Fine and Gray survival models to examine outcome associations.

Results: Dialysis patients had a shorter time from symptom onset to ICU admission compared to other groups (median of 4 [IQR, 2-9] days for maintenance dialysis patients; 7 [IQR, 3-10] days for non-dialysis-dependent CKD patients; and 7 [IQR, 4-10] days for patients without pre-existing CKD). More dialysis patients (25%) reported altered mental status than those with non-dialysis-dependent CKD (20%; standardized difference=0.12) and those without pre-existing CKD (12%; standardized difference=0.36). Half of dialysis and non-dialysis-dependent CKD patients died within 28 days of ICU admission versus 35% of patients without pre-existing CKD. Compared to patients without pre-existing CKD, dialysis patients had higher risk for 28-day in-hospital death (adjusted HR, 1.41 [95% CI, 1.09-1.81]), while patients with non-dialysis-dependent CKD had an intermediate risk (adjusted HR, 1.25 [95% CI, 1.08-1.44]).

Limitations: Potential residual confounding.

Conclusions: Findings highlight the high mortality of individuals with underlying kidney disease and severe COVID-19, underscoring the importance of identifying safe and effective COVID-19 therapies in this vulnerable population.

Keywords: COVID-19 outcome; Coronavirus disease 2019 (COVID-19); altered mental status; chronic kidney disease (CKD); clinical course; clinical trajectory; critical illness; dialysis; end-stage kidney disease (ESKD); end-stage renal disease (ESRD); glomerular filtration rate (GFR); in-hospital mortality; intensive care unit (ICU); prognosis; renal function; severe COVID-19; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Graphical abstract

Figure 1

Trajectories of key laboratory values in the first 14 days after intensive care unit (ICU) admission. Median values are presented in the figure. Dialysis represents patients with pre-existing kidney failure receiving maintenance dialysis. CKD represents patients with pre-existing non-dialysis-dependent CKD. No kidney disease represents patients without pre-existing CKD. Figure S1 displays analogous figures for the laboratory values of creatinine, interleukin 6, fibrinogen, D-dimer, direct bilirubin, and troponin I. Abbreviations: CKD, chronic kidney disease; CRP, C-reactive protein.

Figure 2

Patient disposition at 14 and 28 days after intensive care unit (ICU) admission. Dialysis represents patients with pre-existing kidney failure receiving maintenance dialysis. CKD represents patients with pre-existing non-dialysis-dependent CKD. No kidney disease represents patients without pre-existing CKD. Abbreviation: CKD, chronic kidney disease.

Figure 3

Association between pre-existing CKD and 14-day in-hospital outcomes among critically ill patients with COVID-19. Dialysis represents patients with pre-existing kidney failure receiving maintenance dialysis. CKD represents patients with pre-existing non-dialysis-dependent CKD. No kidney disease represents patients without pre-existing CKD. Fine and Gray proportional subdistribution hazards models were used to estimate the association between the presence of pre-existing CKD (kidney failure receiving maintenance dialysis and non-dialysis-dependent CKD, separately) versus no pre-existing CKD and 14-day in-hospital outcomes. In mortality analyses, hospital discharge was treated as a competing event. In analyses of other outcomes, both in-hospital death and hospital discharge were treated as competing events. Analyses assessing mortality, respiratory failure, shock, and ventricular arrhythmia or cardiac arrest were adjusted for age, sex, race, Hispanic ethnicity, diabetes, hypertension, coronary artery disease, heart failure, and atrial fibrillation or flutter. Analyses evaluating thrombotic events, major bleeding events, and acute liver injury were only adjusted for age, sex, race, and Hispanic ethnicity due to the low number of event counts. Abbreviations: CI, confidence interval; CKD, chronic kidney disease; COVID-19, coronavirus disease 2019; HR, hazard ratio; ref., referent; vent arrhyth/card arrest, ventricular arrhythmia or cardiac arrest.