Is obesity a favorable prognostic factor in peritoneal dialysis patients?

Objective: To determine the influence of an elevated body mass index (BMI) on cardiovascular outcomes and survival in peritoneal dialysis (PD) patient s. Design: Prospective, observational study of a prevalent PD cohort at a sing le center. Setting. Tertiary care institutional dialysis center. Patients: The study included all patients with a BMI of at least 20 who had been receiving PD for at least 1 month as of 31 January 1996 (n = 43). Pat ients were classified as overweight [BMI > 27.5; mean +/- standard error of mean (SEM): 32.1 +/- 1.1; n = 14] or normal weight (BMI 20 - 27.5; mean +/ - SEM: 23.8 +/- 0.4; n = 29). Outcome Measures: Patient survival and adverse cardiovascular events (myoca rdial infarction, congestive cardiac failure, cerebrovascular accident, and symptomatic peripheral vascular disease) were recorded over a 3-year perio d. Results: At baseline, no significant differences were seen between the grou ps in clinical, biochemical, nutritional, or echocardiographic parameters, except for a lower dietary protein intake (0.97 +/- 0.10 g/kg/day vs 1.44 /- 0.10 g/kg/day, p = 0.004) and a higher proportion of well-nourished pati ents by subjective global assessment (100% vs 72%, p < 0.05) in the overwei ght group. After 3 years of follow-up, 29% of overweight patients and 69% o f normal-weight patients had died (p < 0.05). Using a Cox proportional haza rds model, a BMI greater than 27.5 was shown to be an independent positive predictor of patient survival, with an adjusted hazard ratio (HR) of 0.09 [ 95% confidence interval (CI): 0.01 - 0.85; p < 0.05]. However, being overwe ight did not significantly influence myocardial infarction-free survival (a djusted HR: 0.33; 95% Cl: 0.07 - 1.48; p = 0.15) or combined adverse cardio vascular event-free survival (adjusted HR: 0.67; 95% CI: 0.23 - 1.93; p = 0 .46). Conclusions: Obesity conferred a significant survival advantage in our PD p opulation, Obese patients should therefore not be discouraged from receivin g PD purely on the basis of BMI. Moreover, maintaining a higher-than-averag e BMI to preserve "nutritional reserve" may help to reduce the mortality an d morbidity rates associated with PD.