TOPLINE

Nearly 1 in 4 patients admitted to ICUs in Ontario, Canada, had chronic kidney disease (CKD), and increasing disease severity was associated with progressively higher odds of both mortality and initiation of kidney replacement therapy (KRT). Patients on maintenance dialysis had a lower risk for mortality than those with non-dialysis-dependent stage 5 CKD.

METHODOLOGY

• Individuals with CKD, especially end-stage kidney disease, are admitted to ICUs more often than their numbers in the general population would suggest, due to common risk factors for critical illness. However, the link between CKD severity and ICU outcomes remains unclear.
• Researchers conducted a population-based retrospective cohort study in Ontario from 2008 to 2021, examining the link between severity of preexisting CKD and outcomes following ICU admission.
• The analysis included 531,090 adult residents (mean age, 67 years; 57% men) who were admitted to an ICU, with a baseline outpatient serum creatinine measurement taken 7 days to a year prior to admission, which was used to determine kidney function at baseline.
• CKD severity was categorized according to estimated glomerular filtration rate (eGFR) stages using the Kidney Disease Improving Global Outcomes (KDIGO) criteria: no CKD (eGFR ≥ 60 mL/min/1.73 m²; 75%), stage 3a (eGFR, 45-59 mL/min/1.73 m²; 12%), stage 3b (eGFR, 30-44 mL/min/1.73 m²; 7%), stage 4 (eGFR, 15-29 mL/min/1.73 m²; 3%), non-dialysis-dependent stage 5 (eGFR < 15 mL/min/1.73 m²; 1%), and maintenance dialysis (2%).
• The primary outcome was all-cause mortality, assessed at three timepoints: during ICU stay, during hospital stay, and within 90 days after ICU admission. Secondary outcomes were the requirement for KRT during ICU stay, dependency on KRT at 90 days, and length of stay in both ICU and hospital.

TAKEAWAY

• Individuals with CKD stage 3a (adjusted odds ratio [aOR], 1.14; 95% CI, 1.11-1.17), stage 3b (aOR, 1.38; 95% CI, 1.34-1.42), stage 4 (aOR, 1.95; 95% CI, 1.87-2.03), and non-dialysis-dependent stage 5 CKD (aOR, 2.32; 95% CI, 2.14-2.52) had higher odds of 90-day mortality than individuals without CKD. Patients who received maintenance dialysis had lower odds of 90-day mortality (aOR, 1.92; 95% CI, 1.82-2.04) than those with non-dialysis-dependent stage 5 CKD and comparable odds with those with stage 4 CKD.
• The need for KRT in ICU increased progressively with CKD severity; compared with individuals without CKD, those with stage 3a CKD (aOR, 1.79; 95% CI, 1.68-1.90), stage 3b CKD (aOR, 3.02; 95% CI, 2.83-3.22), stage 4 CKD (aOR, 6.71; 95% CI, 6.23-7.22), and non-dialysis-dependent stage 5 CKD (aOR, 32.00; 95% CI, 29.07-35.22) had increased odds of initiating KRT.
• The proportion of individuals who remained dependent on KRT at 90 days after initiating therapy in ICU increased by CKD stage, starting from 7.2% in those without CKD to 14.2% in those with stage 3a, 22.5% in stage 3b, 50.3% in stage 4, and 83.8% in previously non-dialysis-dependent stage 5.
• The length of hospital stay increased progressively with the severity of CKD compared with those without CKD, except for those who were on maintenance dialysis.

IN PRACTICE

“[The study] findings will inform risk prognostication, discussions about goals of care, resource allocation, and health policy initiatives for this large portion of the ICU population,” the authors wrote.

SOURCE

The study was led by Gregory L. Hundemer, MD, MPH, Ottawa Hospital Research Institute, University of Ottawa, Ontario. It was published online in JAMA Network Open.

LIMITATIONS

The observational study design allowed assessment of association but not causation. The most recent eGFR measurement was used to define baseline kidney function, which may have introduced misclassification as kidney function can change over time. Acute kidney injury was not directly accounted for at the time of ICU admission, raising the possibility of residual confounding. Individuals without a baseline outpatient serum creatinine level were excluded, which may have introduced selection bias.

DISCLOSURES

One author was supported by the Department of Medicine, University of Ottawa, and the Dr Shiv L. Jindal Chair for Prevention of Kidney Disease, Ottawa Hospital Research Institute. Another author was supported by grants from the Canadian Institutes of Health Research, the Kidney Foundation of Canada, and the Lorna Jocelyn Wood Chair for Kidney Research. Two other authors disclosed receiving personal fees and nonfinancial support outside the submitted work.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.