Inherent high peritoneal transport and ultrafiltration deficiency: their mid-term clinical relevance.

BACKGROUND: High peritoneal transport has been associated with poorer outcome in peritoneal dialysis (PD) patients, but not necessarily because of PD-dependent conditions. Our primary objective was to analyse the influences of baseline peritoneal small solute transport and ultrafiltration (UF) capacity on patient and technique survival, after adjusting for comorbid conditions. A secondary objective was to determine whether high transport was associated with basal comorbidity.

METHODS: In this prospective observational patient/technique survival study, we followed 410 patients who started PD. At the baseline, we collected data to define comorbidities, tally the Charlson index, determine the baseline mass transfer area coefficients (MTAC) of urea and creatinine, net UF, plasma albumin and residual renal function (RRF). No data other than the information on patient and technique survival were recorded after baseline.

RESULTS: The mean follow-up was 33 +/- 28 months. Dropouts during the study were due to renal transplantation in 140 cases, death in 142 cases and transfer to haemodialysis (HD) in 77 cases. Patients with inherent UF deficiency, high transport rate or both were not significantly different in the survival analysis from the rest. In the Cox hazards analysis, only age, Charlson index and a lower RRF were the significant mortality risk factors. None of the baseline parameters studied was a predictor of technique failure. High transporter patients had lower plasma albumin and UF capacity, comorbidity and more frequent liver diseases than the rest. Moderate to severe liver disease (n = 14) was significantly associated with the inherent high transport status, but was never accompanied by UF failure (UFF). UFF patients showed higher RRF, creatinine-MTAC and age.

CONCLUSIONS: Neither the high transport nor the inherent UFF status has any influence on patient and technique survival. The inherent high small solute transport status is associated with hypoalbuminaemia and a greater comorbidity index. The Charlson index, age and lower RRF are the only independent predictors of mortality. Technique dropout is not predicted by any of the variables studied at the baseline.