Can convective therapies improve dialysis outcomes?

Convective treatments are characterized by enhanced removal of middle and large molecular weight solutes, important in the genesis of many complications of hemodialysis, compared with conventional low-flux hemodialysis. The availability of these techniques represented an intriguing innovation and a possible means to improve the still poor prognosis of hemodialysis patients. In this study we will critically review the most important published studies evaluating the impact of convective treatments on dialysis outcomes.

The Hemodialysis (HEMO) study showed that greater urea removal nonsignificantly reduces the relative risk of mortality and that also high-flux hemodialysis was associated with a nonsignificant reduction, although a secondary analysis pointed to an advantage for high-flux membranes in subgroups of patients. More recently, the Membrane Permeability Outcome (MPO) study found that survival could be improved by use of high-flux membranes compared with low-flux dialysis in high-risk patients as identified by serum albumin < or =4 g/dl as well as in people with diabetes. In an observational study, hemodiafiltration with large reinfusion volume has been associated with a lower relative risk of mortality, compared with low-flux hemodialysis.

The biologic plausibility of advantages of convective treatments and the results of the MPO and Dialysis Outcomes and Practice Patterns (DOPPS) studies are supporting rationales for the use of convective treatments to improve survival and delay long-term complications of hemodialysis patients.