Survival Advantage of Normal Weight in Peritoneal Dialysis Patients

INTRODUCTION: A high body mass index (BMI) is a positive predictor of outcome in hemodialysis. But reports for peritoneal dialysis (PD) have been less numerous. The aim of the present investigation was to study the association between BMI and survival among PD patients and to discuss the main risk factors affecting survival. MATERIALS AND METHODS: A total of 159 patients who received PD from 1 January 2006 to 31 December 2010 at the Department of Nephrology in the Third Affiliated Hospital of Soochow University were enrolled in the study. Blood samples and baseline characteristics of the study cohort were obtained at the start of PD. Patient survival status was recorded through 31 December 2010. RESULTS: Patients were stratified into two groups as normal weight (BMI, 18.5-24.9) and overweight (BMI, 25.0-29.9). Kaplan-Meier survival curve revealed that the normal weight patients had survival advantage over overweight patients (p < 0.01, by log-rank test). Cox proportional hazard models revealed that BMI, age, diabetes mellitus, coronary vascular disease, congestive heart failure and lipoprotein(a) (Lp(a)) were significant risk factors associated with all-cause mortality (p < 0.05). After adjustment for these covariates, survival was consistently higher for normal weight patients (p < 0.01). Furthermore, the study demonstrated that normal weight patients had lower serum Lp(a) (p < 0.05), C-reactive protein (CRP) (p < 0.05), and peritonitis rate (p < 0.05) compared with overweight patients. CONCLUSION: The results indicated that normal BMI at the commencement of PD had significant survival advantage in our study. The mechanisms for this might be related to lower cardiovascular risk, less chronic inflammation, and peritonitis prevalence.