The Association of Body Mass Index, Body Fat Percentage, and Mortality in Hemodialysis Patients: A 3.5-Year Cohort Study

Yann-Hwa Wang ； Chun-Wu Tung ； Yung-Chien Hsu ； Yun-Tung Chen ； Ya-Hsueh Shih ； Chun-Liang Lin

《Acta Nephrologica》 34卷1期 (2020/03) Pp. 4-13

https://doi.org/10.6221/AN.202003_34(1).0002

摘要

BACKGROUND: High body mass index (BMI) in hemodialysis (HD) patients is associated with better survival. However, BMI measures do not differentiate between lean body mass and fat. In this study, we used BMI and body fat percentage (BF%) together to assess the mortality risk in HD patients. METHODS: In this follow-up cohort study, 147 patients on maintenance HD were enrolled and followed from February 2009 to August 2012. These patients were stratified according to their median BMI and BF% into four groups (Group 1: low BMI and low BF%; Group 2: low BMI and high BF%; Group 3: high BMI and low BF%; Group 4: high BMI and high BF%). All-cause mortality among these four groups was studied by Kaplan-Meier survival analysis and Cox proportional hazards model. RESULTS: The median BMI and BF% of these 147 patients were 22.5 kg/m^2 and 27.5 %, respectively. The cumulative rate of death was the highest in Group 2 (38.9%). Although the initial survival analysis did not reach the level of significance (P = 0.15 by log-rank test), further analysis showed that patients with low BMI and high BF% had a significantly worse survival than the other patients (P = 0.02 by log-rank test). In multivariate Cox regression analysis, the mortality risk was significantly higher in Group 2 (adjusted hazard ratio, 6.49; 95% confidence interval, 1.46-28.79; P = 0.01) as compared to Group 4 (reference group). There was no significant difference between Group 1, Group 3, and Group 4 in terms of mortality risk, whereas age and BF% were found to be significant risk factors in the multivariate Cox model. Further analysis also identified female, old age, and BMI ＞ 22.5 kg/m^2 as risks for the development of high-fat percentage. CONCLUSION: This study indicates that low BMI with high BF% is a significant predictor of mortality in HD patients. Therefore, it is important to early identify these high-risk patients and intervene in the underlying conditions to reduce mortality.

關鍵字

body fat percentage ； body mass index ； hemodialysis ； mortality ； sarcopenic obesity