Background/Aims: Treatment time is associated with survival in hemodialysis (HD) patients and with convection volume in hemodiafiltration (HDF) patients. High-volume HDF is associated with improved survival. Therefore, we investigated whether this survival benefit is explained by treatment time.
Methods: Participants were subdivided into four groups: HD and tertiles of convection volume in HDF. Three Cox regression models were fitted to calculate hazard ratios (HRs) for mortality of HDF subgroups versus HD: (1) crude, (2) adjusted for confounders, (3) model 2 plus mean treatment time. As the only difference between the latter models is treatment time, any change in HRs is due to this variable. Results: 114/700 analyzed individuals were treated with high-volume HDF. HRs of high-volume HDF are 0.61, 0.62 and 0.64 in the three models, respectively (p values <0.05). Confidence intervals of models 2 and 3 overlap.
Conclusion: The survival benefit of high-volume HDF over HD is independent of treatment time.

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Blood Purification

de Roij van Zuijdewijn, C., Nubé, M., ter Wee, P., Blankestijn, P., Lévesque, R., van den Dorpel, M., … Grooteman, M. (2015). Treatment Time or Convection Volume in HDF. Blood Purification, 40(1), 53–58. doi:10.1159/000430903