Low-Dose Continuous Kidney Replacement Therapy and Mortality in Critically Ill Patients With Acute Kidney Injury: A Retrospective Cohort Study

Abstract

Rationale & Objective

Continuous kidney replacement therapy (CKRT) is preferred when available for hemodynamically unstable acute kidney injury (AKI) patients in the intensive care unit (ICU). The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend a delivered CKRT dose of 20–25 mL/kg/h, however in Japan, doses are typically below this recommendation due to government health insurance system restrictions. This study investigated the association between mortality and dose of CKRT.

Study Design

Single-center retrospective cohort study.

Setting

& Participants: Critically ill patients with AKI treated with CKRT at a tertiary Japanese university hospital between January 1, 2012, and December 31, 2021.

Exposure

Delivered CKRT doses below or above the median.

Outcome

90-day mortality after CKRT initiation.

Analytical Approach

Multivariable Cox regression analysis and Kaplan–Meier analysis.

Results

The study population consisted of 494 patients. The median age was 72 years, and 309 patients (62.6%) were men. Acute tubular injury was the leading cause of AKI, accounting for 81.8%. The median delivered CKRT dose was 13.2 mL/kg/h. 456 (92.3%) study participants received delivered CKRT doses below 20 mL/kg/h, and 204 (41.3%) died within 90 days after CKRT initiation. Multivariable Cox regression analysis revealed increased mortality in the below-median group (hazard ratio: 1.73, 95% confidence interval: 1.19–2.51, P=0.004). Additionally, a significant, inverse, non-linear association between 90-day mortality and delivered CKRT dose was observed using delivered CKRT dose as a continuous variable.

Limitations

Single-center, retrospective, observational study.

Conclusions

A lower delivered CKRT dose was independently associated with higher 90-day mortality among critically ill patients who mostly received dosing below current KDIGO recommendations.