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/PCr; 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/PCr (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/V urea (rho = 0.42), and total CCr (rho = 0.30). The group with serum C-reactive protein (sCRP) ⊕ 10 mg/L had a higher proportion of patients with reduced (< 1000 mL) TFR compared to the group with sCRP < 10 mg/(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.