Objective: Obesity may negatively impact clinical outcomes of peritoneal dialysis (PD) patients. However, obesity is defined differently in Japan, and its impact on PD-related outcomes remains unclear. In current study, we aimed to examine the association of high body mass index (BMI) with the complete hemodialysis (HD) transfer, transition to HD and PD/HD hybrid therapy, peritonitis, catheter exit-site and tunnel infection (ESI/TI), and heart failure-related hospitalization. Design and method: This retrospective cohort study included 120 patients who underwent PD catheter insertion between January 2008 and June 2018. BMI ≧ 25 kg/m2, which was calculated from the height (m) and body weight (kg) at the time of PD catheter insertion, was defined as high BMI. Patients who develop solute retention or fluid overload with PD alone could choose to transfer first to PD/HD hybrid therapy, wherein patients usually undergo PD 5–6 days a week along with once-weekly HD, instead of directly transferring to HD alone. Association between high BMI and outcomes were analyzed by the log-rank test and the Cox proportional hazards models. Results: The follow-up duration was 46.2 (23.3–75.3) months. Time until transfer to HD and hybrid therapy was significantly shorter in the high BMI group than in the low one, whereas time until transfer to HD was not significantly different between both groups (P < 0.001 and 0.18, respectively). Peritonitis-free and ESI/TI-free survival were significantly shorter in the high BMI group than in the low one (P = 0.006 and 0.03, respectively). After adjusting for age, sex, diabetes mellitus, estimated glomerular filtration rate, BMI ≧ 25 kg/m2 remained as a significant risk factor for transferring to HD and PD/HD hybrid therapy, peritonitis, and ESI/TI (hazard ratio [HR] 2.60, P < 0.001; HR 2.08, P = 0.01; HR 2.64, P = 0.02, respectively). Conclusions: High BMI, defined as BMI ≧ 25 kg/m2, is a risk factor for transition to HD and PD/HD hybrid therapy, peritonitis, and ESI/TI. However, high BMI is not associated with early complete HD transfer in Japan, where PD/HD hybrid therapy is commonly used.
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