Improved outcome for haemodialysis patients treated with high-flux membranes.

Improved survival for haemodialysis patients has been reported for synthetic, high-flux biocompatible membranes. The reported data fail to answer the question whether improved survival is related to an effect of enhanced biocompatibility or to increased clearance of larger molecular species of putative uraemic toxins. A retrospective analysis of 715 patients treated by continuous haemodialysis for up to 5 years was undertaken. Low-flux polysulfone dialysis was used exclusively for 252 patients and 463 patients were exposed for at least 3 months to high-flux polysulfone dialysis. Patients treated with high-flux dialysis had a lower mortality (21 vs 36 per 1000 years) and significantly lower standardized mortality ratio. For non-diabetic patients the 5-year probability of survival was significantly greater for high-flux patients (Kaplan-Meier: 92% vs 69%; P=0.036). High-flux dialysis significantly reduced the adverse effect of age on survival. In a Cox proportional hazard model membrane flux (high vs low) was one of the covariates with strong predictor value for reduction of death risk in non-diabetic patients. Although other variables may explain the better survival of patients exposed to high-flux dialysis the data reported here suggest that higher membrane flux, implying higher clearance of larger molecular species and independent of biocompatibility, is associated with improved survival for haemodialysis patients.