Peritoneal Transport Status Correlates With Morbidity But Not Longitudinal Change of Nutritional Status of Continuous Ambulatory Peritoneal Dialysis Patients: A 2-Year Prospective Study
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Cross-sectional studies show that peritoneal transport status is associated with nutritional status and clinical outcome of continuous ambulatory peritoneal dialysis (CAPD) patients. High transporters often are assumed to have progressive malnutrition as a result of fluid overload and nutrient loss in dialysis effluent. There are few prospective data to confirm this assumption, however. We studied 235 unselected CAPD patients to examine this possibility. There were 58 new cases and 177 prevalent cases. A standard peritoneal equilibration test was performed at enrollment. All patients were followed for 2 years. Dialysis adequacy and nutritional assessment, including serum albumin, protein nitrogen appearance, and lean body mass, were performed at 0, 12, and 24 months. Clinical outcome included hospitalization, actuarial patient survival, and technique survival. The mean age was 51.6 +/- 12.4 years. The mean 4-hour dialysate-to-plasma ratio of creatinine was 0.57 +/- 0.12 for all cases (0.60 +/- 0.12 for new cases). Patients were classified into three groups: high/high-average (H/HA) (63 cases), low-average (LA) (105 cases), and low (L) (67 cases) transporters. Baseline demographic data and total Kt/V were similar in all transport groups. There were weak correlations between 4-hour dialysate-to-plasma ratio of creatinine and baseline serum albumin (r = -0.249, P: < 0.001), protein nitrogen appearance (r = -0.190, P: < 0.01), and percentage of lean body mass (r = -0.194, P: < 0.01). The H/HA group was a specific but not a sensitive predictor of poor baseline nutritional status. There was no significant change in any nutritional indices after 2 years in new cases and prevalent cases, regardless of transport status. The differences in nutritional indices between groups remained unchanged during the study period. There was a significant difference in hospitalization rate among peritoneal transport groups (median 12 versus 7 versus 3 days per year for H/HA, LA, and L groups, Kruskal-Wallis test, P: < 0.05). The difference remained similar when new cases and prevalent cases were analyzed separately. The L group had slightly better 2-year patient survival than the H/HA group (90.2% versus 83.3%), but the result was not statistically significant. We conclude that peritoneal transport status is not associated with longitudinal change of nutritional parameters, although transport status is associated with short-term patient morbidity. Further study is needed to identify the mechanisms of poor clinical outcome in high peritoneal transporters.
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