Hemodiafiltration: what is new in the literature

Nowadays it is widely acknowledged that, compared with standard hemodialysis (HD), on-line hemodiafiltration (HDF) may allow better results in terms of intra-dialytic tolerance, nutritional status, maintenance of residual renal function, responsiveness to erythropoietin and phosphorus control. However, so far controlled studies have not had sufficient power to demonstrate any superiority of HDF in reducing morbidity and mortality. Two recent prospective randomized controlled studies, the “Convective Transport Study” (CONTRAST) and the “Comparison of Post-dilution Online Hemodiafiltration and Hemodialysis” study (TURKISH OL-HDF STUDY), have compared patient survival and cardiovascular events rate in HDF and HD. Although the two studies were large enough and properly designed to evaluate such an important outcome, it was not possible to find significant differences between the treatments (HDF vs low-flux HD in the CONTRAST and HDF vs high-flux HD in the TURKISH STUDY). In post-hoc analyses, both studies showed that high convective volumes were associated with a better outcome. However these results need to be considered just hypothesis-generating and require to be tested in adequate trials. Results coming from the ongoing Spanish and French studies will help us in better understanding the important role of HDF in everyday clinical practice.