Long-term follow-up of body size indices, residual renal function, and peritoneal transport characteristics in continuous ambulatory peritoneal dialysis.

Technique survival in continuous ambulatory peritoneal dialysis (CAPD) depends mostly on clearances in relation to body size and residual renal function (RRF). Our clinical impression has been that when RRF fails, larger patients leave CAPD sooner than smaller patients do. Peritoneal equilibration tests (PETs) and 24-hour adequacy evaluations performed in 277 patients in a single center from 1986 through 2009 were abstracted from the existing peritoneal dialysis adequacy database. A PET (using 2 L of 2.5% dextrose dialysis solution) was performed in 272 patients during the first 4 months of dialysis. Every 3 months, the patients brought their 24-hour urine and dialysate collections for adequacy evaluations and had height and weight recorded. Body surface area (BSA), body mass index (BMI), and total body water (TBW) were calculated. There were 1372 adequacy evaluations abstracted. The number of patients gradually declined over time because of death (28%) or transfer to other peritoneal regimens (25%) or to hemodialysis (23%). A small number of patients received a kidney graft (6%) or left CAPD for other reasons (12%); only 6% of patients remained on CAPD after 80 months of treatment. The mean (+/- standard deviation) PET 4-hour values were 0.652 +/- 0.128 for dialysate-to-plasma (D/P) ratio of creatinine (Cr), 0.403 +/- 0.0969 for 4-hour dialysate-to-initial dialysate (D/D0) glucose concentration ratio, and 2336 +/- 211 mL for the drain volume. There was no correlation between PET D/P Cr and BSA (r = 0.0051, p = 0.934), PET D/D0 glucose and BSA (r = 0.0042, p = 0.945), or PET drain volume and TBW. The correlations with other size indicators were very poor. None of the large patients (BSA > 1.9 m2, weight > 75 kg, BMI > 25 kg/m2) remained on CAPD for more than 80 months once they lost RRF. These results confirm our impression that, with declining RRF, larger patients do not continue CAPD as long as smaller patients do.