title: Treatment Time or Convection Volume in HDF: What Drives the Reduced Mortality Risk?
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  The survival benefit of high-volume HDF over HD is independent of treatment time.
authors.affiliation: Department of Nephrology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Camiel L M
authors.initials: CL
authors.lastname: de Roij van Zuijdewijn
authors.forename: Menso J
authors.initials: MJ
authors.lastname: Nubé
authors.forename: Piet M
authors.initials: PM
authors.lastname: ter Wee
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Blankestijn
authors.forename: Renée
authors.initials: R
authors.lastname: Lévesque
authors.forename: Marinus A
authors.initials: MA
authors.lastname: van den Dorpel
authors.forename: Michiel L
authors.initials: ML
authors.lastname: Bots
authors.forename: Muriel P C
authors.initials: MP
authors.lastname: Grooteman
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D017583:Hemodiafiltration / Q000379:methods; D006801:Humans; D007676:Kidney Failure, Chronic / Q000401:mortality* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D016896:Treatment Outcome