The Extracellular Water Corrected for Height Predicts Technique Survival in Peritoneal Dialysis Patient

OBJECTIVE: Most patients on peritoneal dialysis (PD) consume a normal Western diet that contains a large amount of salt. This causes increase in extracellular volume ("fluid overload") that has to be removed mostly with the dialysis fluid, as residual renal function (if present) cannot cope with it. In the present study, we prospectively investigated whether an increased extracellular volume (corrected for height) predicted technique survival in PD patients. MATERIAL and METHODS: Ninety-five prevalent PD patients from one center (mean age 50 +/- 13 years, 10 of them diabetic) were studied. Extracellular water (ECW), total body water (TBW), and intracellular water (ICW) were measured by multi-frequency bioimpedance analysis (m-BIA). Echocardiography was performed in all patients. Volume status was also evaluated by measuring left atrium diameter (LAD) and left ventricular end-diastolic diameter (LVEDD). Demographical, biochemical analyses, peritoneal equilibration test, weekly total Kt/V urea and weekly total creatinine clearance (CCr) results were obtained from patient chart. We identified a cut-off value for ECW/height by drawing ROC curves that differentiate patients with FO and those without, using LAD and LVEDD measured by echocardiography as confirmatory parameters. Technique survival (TS) was defined as the time on PD treatment until transfer to hemodialysis. Technique survival (TS) was assessed at the end of the follow-up and significant predictors of technique survival were investigated. RESULTS: During the follow-up, 62 patients dropped out. Thirty-six patients were switched to hemodialysis (severe peritonitis in twelve, hernia in one, peritoneal leaks in five, inadequate dialysis in seventeen and unwillingness in one patient), twelve patients received transplants, five patients were transferred to other center and nine patients died (4 patients from infection, 4 patients from cardiovascular disease and 1 patient from malignancy). Patients switched to hemodialysis were older and had higher duration of PD treatment, body mass index, ECW/height and LAD than patients that stayed on PD. Patients that switched to HD also had significantly lower weekly total KT/V urea, weekly total CCr and daily total urine volume than patients that stayed on PD. On ROC analysis, we found a cut-off value for ECW/height of 10.5 liters/m with specificity of 78 % and sensitivity of 75% for the diagnosis of FO. Patients with the ratio of ECW/height values above the cut-off values had significantly worse technique survival than those with ECW/height below 10.5 L/m (mean survival, 28.7 +/- 2.6 vs. 35.1 +/- 1.9 months; p=0.016). On multivariate analysis, weekly total CCr, serum CRP level and ECW/height above 10.5 L/m were independent predictors of technique failure. CONCLUSION: An increased extracellular volume corrected for height as a fluid overload marker is associated with decreased technique survival in PD patients.