Association between mortality and age-dose combination in continuous kidney replacement 
therapy for critically ill patients with acute kidney injury under Japanese healthcare system

Abstract

The approach to determining the dose of continuous kidney replacement therapy (CKRT) in Japan differs from approaches used abroad. Under the Japanese healthcare system, the prescribed daily volumes of dialysate and replacement fluid are fixed, and thus the CKRT dose varies from one individual to another depending on their body weight. We therefore retrospectively analyzed an observational cohort to assess how Japan’s unique approach affects mortality by age. We categorized 494 patients who underwent CKRT at Nara Medical University Hospital into four groups based on age (< 75 years or ≥ 75 years) and CKRT dose (above or below the median, 13.2 mL/kg/h) and then used multivariable Cox regression analysis to compare 90-day mortality between the groups. A higher CKRT dose was observed to be independently associated with lower 90-day mortality, regardless of age. A relatively higher CKRT dose might have contributed to improved survival in elderly patients, especially who tend to have lower body weight. The current Japanese approach of a fixed prescription of dialysate and replacement fluids might therefore mitigate age-related differences in mortality, highlighting the need to reconsider the CKRT dose prescription to ensure no variance with a patient’s body weight.