Influence of peritoneal transport rate, inflammation, and fluid removal on nutritional status and clinical outcome in prevalent peritoneal dialysis patients

Abstract

Objective: To evaluate the possible associations between peritoneal transport rate (PTR), fluid removal, inflammation, and nutritional status in patients treated with peritoneal dialysis (PD) for more than 6 months, and the impact of these factors on subsequent patient survival.

Design and patients: A prospective study of 82 PD patients (48 males) that had been treated with PD more than 6 months. Based on the dialysate-to-plasma creatinine ratio at 4 hours of dwell (D/P Cr; mean +/- 1 SD), the patients were classified as having a high (H), high-average (HA), low-average (LA), or low (L) PTR.

Setting: Single PD unit in a university hospital.

Main outcome measures: The PTR, evaluation of adequacy of dialysis and nutritional status, and biochemical analyses were assessed at 10.8 +/- 2.8 months after the start of PD.

Results: Compared to L and LA (L/LA) transporters, H and HA (H/HA) transporters had increased dialysate protein loss, glucose absorption from dialysate, and peritoneal creatinine clearance (CCr), and decreased night ultrafiltration volume and total Kt/V urea. However, nutritional variables, 24-hour total fluid removal (TFR), total CCr, and residual renal function were not significantly different between the two groups. The 24-hour TFR correlated significantly with D/P Cr (rho = -0.25), mean arterial pressure (rho = -0.23), serum albumin (rho = 0.25), normalized protein equivalent of total nitrogen appearance (rho = 0.34), lean body mass (LBM) calculated from creatinine kinetics (rho = 0.41), total Kt/N urea (rho = 0.42), and total CCr (rho = 0.30). The group with serum C-reactive protein (sCRP) > or = 10 mg/L had a higher proportion of patients with reduced (< 1,000 mL) TFR compared to the group with sCRP < 10 mg/L (38% vs 16%, p = 0.04). Two-year patient survival rates from the time of the assessment were not different between the different transport groups (78% vs 73% for H/HA and L/LA, p = 0.99). Upon Cox proportional hazards multivariate analysis, age and high sCRP were independent predictors of mortality.

Conclusions: This study shows that, in a selected group of prevalent PD patients assessed after more than 6 months of PD therapy, (1) inflammation was an independent predictor for mortality; (2) reduced TFR was associated with impaired nutritional status, decreased small solute clearance, and inflammation; and (3) peritoneal transport status was not significantly associated with nutritional status and was not associated with subsequent patient survival. These results indicate that a high peritoneal solute transport rate, as such, should not be regarded as a relative contraindication for PD. Instead, the results suggest that more attention should be given to inflammation and inadequate fluid removal as predictors of mortality in PD patients.