Long-term outcomes in online hemodiafiltration and high-flux hemodialysis: a comparative analysis

Abstract

Background and objectives: Theoretical advantages exist of online hemodiafiltration (HDF) over high-flux hemodialysis (HD), but outcome data are scarce. Our objective was to compare outcomes between these modalities.

Design, setting, participants, & measurements: We studied 858 incident patients in our incremental high-flux HD and online HDF program during an 18-yr period. We compared outcomes, including survival, in those who were treated predominantly with HDF (>50% sessions) and those with high-flux HD. Survival comparisons used a Cox model taking into account the time-varying proportion of time spent on HDF. All data were prospectively collected.

Results: A total of 152,043 sessions were delivered as HDF and 291,222 as high-flux HD. A total of 232 (27%) patients were treated predominantly with HDF and 626 (73%) with high-flux HD. Total Kt/V, serum albumin, erythropoietin resistance index, and BP were similar in both groups up to 5 yr after HD initiation. Intradialytic hypotension was less frequent in the predominant HDF group. Predominant HDF treatment was associated with a reduced risk for death after correction for confounding variables. In a second Cox model, proportion of time spent on HDF predicted survival, such that patients who were treated solely by HDF would have a hazard for death of 0.66 compared with those who solely used high-flux HD.

Conclusions: We found no benefits of HDF over high-flux HD with respect to anemia management, nutrition, mineral metabolism, and BP control. The mortality benefit associated with HDF requires confirmation in large randomized, controlled trials. These data may contribute to their design.

Figure 1.

Total Kt/V_urea in patients who were on predominantly high-flux HD and HDF. The incremental dialysis algorithm adjusted dialysis dosage to a total Kt/V of 1.2 regardless of dialysis type. Kt/V_Total comprised the sum of Kt/V_Dialysis and Kt/V_Renal. There was no significant difference in Kt/V_Total between patients who were on predominantly high-flux HD or HDF at all time points except at 24 mo.

Figure 2.

BP in patients who were treated with predominantly high-flux HD and HDF at different time points. There was no significant difference in BP between groups at any time point except that predialysis systolic BP was significantly higher in the high-flux HD group at 36 mo (P = 0.02).

Figure 3.

Ultrafiltration rate in patients who were treated with predominantly high-flux HD and HDF at different time points. UF rate was significantly higher in the group that was treated with predominantly HDF at each time point up to 60 mo.

Figure 4.

Cox proportional hazards model demonstrating survival differences between patients in whom the predominant treatment modality was HDF and high-flux HD. Treatment with HDF was an independent risk factor predicting a lower hazard for death (HR 0.46; P < 0.001). Other factors included in the model are shown in Table 5.