Effect of dialysis membranes and middle molecule removal on chronic hemodialysis patient survival

The type of dialysis membrane used for routine therapy has been recently sh own to correlate with the survival of chronic hemodialysis patients, We exa mined whether this effect of dialysis membrane could be explained by differ ences in dialyzer removal of middle molecules using data from the 1991 Case Mix Adequacy Study of the United States Renal Data System, The sample anal yzed included patients who had been treated by hemodialysis for 1 year or m ore, who were dialyzed with the 19 most commonly used dialyzers in 1991, an d for whom delivered urea Kt/V could be calculated from predialysis and pos tdialysis blood urea nitrogen concentrations. Vitamin B-12 (1,355 daltons) was used as a marker for middle molecules, and the clearance of Vitamin Bla was estimated based on in vitro data. After adjustments for case mix, como rbidities, and urea KW, the relative risk of mortality for a 10% higher cal culated total cleared Volume of Vitamin B-12 was 0.953 (P < 0.0001 v 1.000) . Similar results were obtained when middle molecule removal was adjusted f or body size. We conclude that both small and middle molecule removal indic es appear to be independently associated with the risk of mortality in chro nic hemodialysis patients, Differences in mortality when using different ty pes of dialysis membrane may be explained by differences in middle molecule removal. This is a US government work. There are no restrictions on its use.