Effect of the membrane biocompatibility on nutritional parameters in chronic hemodialysis patients

Malnutrition is highly prevalent in chronic hemodialysis patients and is an important determinant of their morbidity and mortality. Several recent studies have suggested that the inflammatory response associated with the biocompatibility of the dialysis membranes is a potential contributing factor. In a prospective study of 159 new hemodialysis patients from two centers randomized to either a low-flux biocompatible (BCM) membrane or a low-flux bioincompatible (BICM) membrane, we measured the long-term effects of biocompatibility on several nutritional parameters, including estimated dry weight, serum albumin, insulin-like growth factor-1 (IGF-1), and prealbumin over 18 months. Our results show that the BCM group had a mean (+/- SD) increase in their dry weight of 2.96 +/- 6.88 kg at month 12 and 4.36 +/- 8.57 kg at month 18 (P < 0.05 vs. baseline for both), whereas no change in mean weight was observed in BICM group. Following initiation of hemodialysis, a significant increase was observed in serum albumin levels in both groups of patients. However, the biocompatible group had an earlier and more marked increase in serum albumin levels compared to the BICM group. The average increase in serum albumin compared to baseline was consistently greater than 0.25 g/dl after seven months in the BCM group, but did not reach this level until 12 months after initiation of dialysis in the BICM group. The difference between the groups was statistically significant at months 7, 8, and 10 (P < 0.05, higher in the BCM group). Furthermore, the overall difference in serum albumin concentration between the two groups was larger in the center where the dose of dialysis was equivalent (P < 0.001). A consistently higher value was also observed in IGF-1 levels for BCM patients compared to BICM group (P = NS). In a further analysis, changes in IGF-1 levels, but not prealbumin, predicted the subsequent changes in serum albumin. We conclude that biocompatible hemodialysis membranes favorably impact on the nutritional status of chronic hemodialysis patients, independently of the flux characteristics of the membranes, and that IGF-1 may be an early marker of nutritional status.