Impact of peritoneal solute transport rate on nutritional status and clinical outcome in peritoneal dialysis patients

Abstract

The transport characteristics of the peritoneal membrane may be influenced by inflammation and various comorbid diseases (CMD) in peritoneal dialysis (PD) patients. On the other hand, the peritoneal solute transport rate (PSTR) may influence patient characteristics such as nutritional status as well as the clinical outcome of PD patients. The aim of the present investigation was to elucidate the impact of PSTR on nutritional status and clinical outcome in PD patients.

I. Malnutrition (MN) as assessed by subjective global assessment was common in Korean patients at initiation of PD. Initial MN and initial lean body mass calculated from creatinine kinetics (LBM) were independent predictors of mortality. Initial nutritional status, therefore, appears to exert a powerful influence on PD patient survival.

II. At the start of PD, 49% of the patients with CMD had MN and 78% of patients with MN had CMD. MN alone was associated with a statistically insignificant increase in mortality but the combined presence of MN and CMD was associated with significantly higher mortality. This underlines the importance of CMD as a cause of poor clinical outcome in malnourished PD patients.

III. At the start of PD, high transporters had a higher proportion of patients with CMD. High PSTR had a significant impact on patient survival. However, high PSTR did not affect patient survival in patients without CMD. Thus, the association between initial high PSTR and high mortality may be in part due to an increased prevalence of CMD in high transporters.

IV. Patients with low residual renal function (RRF) had more often high C-reactive protein (CRP>=10mg/]_). FIR correlated negatively with serum albumin concentrations and positively with serum CRP levels. Patient survival was significantly lower in the patients with low RRF, with high CRP, and with more than two of the following: low RRF, high CRP, and high PTR. In contrast, patients with high PSTR had high mortality only during the initial year on PD. These results indicate the importance of RRF and inflammation as predictors of mortality in PD patients whereas the predictive power of PSTR as such may loose its significance if these two parameters are taken into consideration.

V. In patients who were assessed after on average 10.8 months of PD treatment, nutritional variables, 24-h total fluid removal (TFR), Kt/Vurea, and creatinine clearance (CCr) were not different between the different transport groups. TFR correlated with D/P Cr, serum albumin, protein intake, LBM, Kt/Vurea, and CCr. Patients with high CRP had a higher proportion of patients with reduced (<1000 in]) TFR compared to patients with normal CRP (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. Inflammation was an independent predictor of mortality. These results indicate that a high PSTR 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.

VI. During the 1st year on PD, patients with increased PSTR had a low RRF and more often high CRP compared to patients with decreased or unchanged PSTR. Patients with a decrease in RRF>1.9 ml/min during the 1st year on PD had more often high CRP, higher D/P Cr, and higher changes in D/P Cr compared to the patients with a decrease in RRR<1.9 ml/min. High CRP and low RRF were independent factors associated with PSTR during the 1st year on PD. Thus, it is possible that inflammation may cause both an increase in PSTR and a decline in RRF, or that the decline in RRF and the increase in PSTR may induce or aggravate inflammation.