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

Keisuke Okamoto; Hidetada Fukushima; Masahiko Kawaguchi; Kazuhiko Tsuruya

doi:10.1053/j.ajkd.2024.01.526

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

Am J Kidney Dis. 2024 Mar 13:S0272-6386(24)00673-5. doi: 10.1053/j.ajkd.2024.01.526. Online ahead of print.

Authors

Keisuke Okamoto¹, Hidetada Fukushima², Masahiko Kawaguchi³, Kazuhiko Tsuruya⁴

Affiliations

¹ Department of Nephrology, Nara Medical University, Nara, Japan. Electronic address: okamoto@naramed-u.ac.jp.
² Department of Emergency and Critical Care Medicine, Nara Medical University, Nara, Japan.
³ Department of Anesthesiology, Nara Medical University, Nara, Japan.
⁴ Department of Nephrology, Nara Medical University, Nara, Japan.

PMID: 38490319
DOI: 10.1053/j.ajkd.2024.01.526

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 20-25mL/kg/h; however, in Japan the 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 13.2mL/kg/h. Among the study participants, 456 (92.3%) received delivered CKRT doses below 20mL/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 (HR, 1.73 [95% CI, 1.19-2.51], P=0.004). Additionally, a significant, inverse, nonlinear 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 the current KDIGO recommendations.

Plain-language summary: The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend delivering a continuous kidney replacement therapy (CKRT) dose of 20-25mL/kg/h. However, it is not clear if it is safe to use delivered CKRT doses below this recommendation. In this study, over 90% of the patients received CKRT with a delivered dose below the KDIGO recommendation. We divided these patients into 2 groups based on the median delivered CKRT dose. Our findings show that a delivered CKRT dose below the median was associated with increased risk of death within 90 days. These findings show that 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.

Keywords: Acute kidney injury; KDIGO guidelines recommendation; continuous kidney replacement therapy; delivered continuous kidney replacement therapy dose; mortality.