Supplementary Material for: The Impact of Change in Body Roundness Index on the Clinical Outcome of New Peritoneal Dialysis Patients

Background: Weight gain and central obesity are common in peritoneal dialysis (PD) patients. In the general population, Body Roundness Index (BRI) has been found to be a convenient anthropometric measurement for the assessment of central obesity and visceral adiposity. However, the role of BRI in PD patients has not been explored. Method: We recruited 145 new PD patients. BRI, body composition by bioimpedance spectroscopy, and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) were measured at baseline and then after one year of PD. Patients were stratified into four groups based on their changes in BRI after 1 year of PD, using the traditional BRI cutoff of 5. Outcome measures include patient survival and hospitalization rate. Results: The change in BRI after one year of PD had a modest but significant correlation with the change in HOMA-IR (r = 0.497, p = 0.041). For the group with baseline BRI <5, patients who had their BRI rose to ≥5 (low-high group, n = 20) had significantly lower patient and technique survival rates than those whose BRI remained <5 (low-low group, n = 55), and the result remained significant after adjusting for clinical confounders by multi-variable Cox regression (adjusted hazard ratio 2.885, 95%CI 1.278-6.509, p = 0.011). The low-high group also had significantly higher hospitalization rates (2.51 [1.63-3.93] vs 0.98 [0.26-1.91] per year, p = 0.0008) and longer hospitalization stay (17.3 [12.2-35.5] vs 5.0 [1.0-13.3] days per year, p = 0.015) than the low-low group. Conclusion: An increase in BRI after one year of PD was associated with worsening of insulin resistance, worse patient survival, and more hospitalization.