Short-term prognosis of emergently hospitalized dialysis-independent chronic kidney disease patients: A nationwide retrospective cohort study in Japan

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 administrative 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.

Synergic Impact of Body Mass Index, Diabetes, and Age on Long-Term Mortality in Japanese Incident Hemodialysis Patients: A Cohort Study on a Large National Dialysis Registry

OBJECTIVES

The relationships among body mass index (BMI), diabetes, age, and all-cause mortality in hemodialysis patients remain unclear. We examined BMI-stratified relationships between diabetes, age, and the risk of long-term mortality in incident hemodialysis patients.

METHODS

This is a cohort study. Data were obtained from the national dialysis registry in Japan 2007 that included 35,415 incident hemodialysis patients and 6,061 patients aged ≥20 years with BMI data. Patients were divided into 6 categories according to baseline BMI (low: <18.5, normal: 18.5-25, Obesity: ≥25) and the presence or absence of diabetes. The primary outcome was all-cause mortality during a 5-year follow-up. Hazard ratios were estimated using Cox's model for the relationships among diabetes, BMI categories, and all-cause mortality, and adjusted for potential confounders. Patients with a normal BMI and non-diabetic were the reference category. We also examined the effects of age on these relationships.

RESULTS

A total of 6,061 patients, including 3,239 with diabetes, were enrolled. During the follow-up, 31.0% and 30.7% of all and diabetic patients, respectively, died. Cox's regression analysis showed that low BMI, but not obesity, was independently associated with an increased risk of all-cause death in patients with and without diabetes. When patients were divided into 2 groups-younger and older than 60 years-the risk of mortality in both groups was increased in low BMI with diabetes.

CONCLUSIONS

Among Japanese incident hemodialysis patients, low BMI increases the risk of all-cause mortality. The markedly high mortality rate in diabetic patients with low BMI regardless of age warrants attention.