Relationship of peritoneal membrane transport characteristics to the nutritional status in CAPD patients

Abstract

Background. The study was carried out to evaluate the role of individual peritoneal membrane transport characteristics in the nutritional status expressed as the composite nutritional index (CNI). Methods. Cross-sectional analyses of the overall nutritional status of 147 continuous ambulatory peritoneal dialysis (CAPD) patients were performed using the CNI. CNIs based on a scoring system of 10 nutritional indices including subjective global assessment, biochemical parameters and anthropometry were compared according to the results of a standard peritoneal equilibration test (PET). Results. Patients were classified as low (n = 16, 10.9%), low average (n = 59, 40.2%), high average (n = 54, 36.7%) and high (n = 18, 12.2%) transporters based on the D/P(Cr) after 4 h dwells. The mean 4 h D/P(Cr) was 0.65 ± 0.12 (0.34-0.95), and there was no significant correlation between D/P(Cr) and other demographic parameters such as age, duration of peritoneal dialysis and body surface area. D/P(Cr) was correlated with dialytic albumin loss (r = 0.47, P < 0.001), serum albumin (r = -0.46, P < 0.001), serum creatinine (r = -0.38, P < 0.001), serum IGF-1 (r = -0.37, P < 0.01) and LBM(Cr) (r = -0.26, P < 0.05). In high transporters, the serum albumin was significantly lower while dialysate protein and albumin losses were significantly greater compared with low transporters. Serum creatinine and IGF-1 concentrations as well as LBM(Cr) were also decreased in higher transporters. The mean CNI score was 8.1 ± 4.9, with a range of 0-24. CNI was positively correlated with age, duration of peritoneal dialysis, incidence of peritonitis, CRP and dialytic protein loss, whereas it was inversely correlated with ultrafiltration volume, haemoglobin and NPNA. The CNI score was significantly higher in high transporters compared with low transporters (11.7 ± 4.3 vs. 5.9 ± 1.6, P < 0.01). There was also a significant correlation between D/P(Cr) and CNI (r = 0.29, P < 0.05). Multiple regression analysis revealed that the incidence of peritonitis, duration of CAPD, CRP and D/P(Cr) were the independent factors affecting the CNI. Conclusion. Peritoneal membrane transport characteristics correlate with the overall nutritional status of peritoneal dialysis patients assessed by the scoring system of the CNI, although it is associated with a different impact on the individual nutritional indices. The results of this cross-sectional study also suggest that a high permeability state is a risk factor for malnutrition in CAPD patients. Prospective studies evaluating the changes in nutritional parameters among patients with different membrane transport rates are needed to understand better the relationship of peritoneal membrane characteristics to the nutritional status of CAPD patients.