Body mass index and weight change are associated with mortality in chronic kidney disease: A retrospective cohort study using a Japanese medical claims database

Objectives: This study aimed to investigate body mass index (BMI) and rate of weight change associated with adverse outcomes in Asian patients with chronic kidney disease.Methods: A retrospective cohort study was performed between April 2014 and June 2022 using the adminis-trative claims database compiled by the Japan Medical Data Center. Patients were defined as individuals with comorbidities with chronic kidney disease stages 3 to 5 on admission and were aged >40 y with BMI at admission and BMI information from a previous admission 3 to 12 mo earlier. Restricted cubic spline analysis and thin-plate smoothed spline analysis were performed.Results: A total of 10 802 individuals were analyzed. The mean age was 74.6 +/- 11.3 y, number of men was 7175 (66.4%), and 2115 (19.6%) deaths were recorded. Smoothed splines for BMI found that low BMI was associated with high hazard ratio (HR) (BMI = 18.5 kg/m2; HR = 1.3 [1.2-1.4]). Smoothed splines of weight change found higher HR with increasing rate of weight change for both weight gain and loss (weight change rate =-10%; HR = 1.4 [1.3-1.5]; weight change rate = 10%; HR = 1.2 [1.1-1.3]). In thin-plate smoothed spline analysis, the U-curve had a higher odds ratio as BMI decreased in patients with or without dialysis and as the degree of weight change increased.Conclusions: We found trends in BMI and rate of weight change associated with mortality in Asian patients with chronic kidney disease.(c) 2023 Elsevier Inc. All rights reserved.