title: Impact of initial dialysis modality on mortality: a propensity-matched study.
abstract: BACKGROUND
  Whether the choice of dialysis modality in patients with end stage renal disease may impact mortality is undecided. No randomized controlled trial has properly addressed this issue. Propensity-matched observational studies could give important insight into the independent effect of peritoneal (PD) opposed to haemodialysis (HD) on all-cause and cardiovascular mortality.
  
  
  METHODS
  To correct for case-mix differences between patients treated with PD and HD, propensity-matched analyses were utilized in all patients who initiated dialysis as first renal replacement therapy in Norway in the period 2005-2012. PD patients were matched in a 1:1 fashion with HD patients, creating 692 pairs of patients with comparable baseline variables. As-treated and intention-to treat analyses were undertaken to assess cardiovascular and all-cause mortality. Interaction analyses were used to assess differences in the relationship between initial dialysis modality and mortality, between strata of age, gender and prevalent diabetes mellitus.
  
  
  RESULTS
  In the as-treated analyses, initial dialysis modality did not impact 2-year (PD vs. HD: HR 0.87, 95 % CI 0.67-1.12) or 5-year all-cause mortality (HR 0.95, 95 % CI 0.77-1.17). In patients younger than 65 years, PD was superior compared to HD with regard to both 2-year (HR 0.39, 95 % CI 0.19-0.81), and 5-year all-cause mortality (HR 0.49, 95 % CI 0.27-0.89). Cardiovascular mortality was also lower in the younger patients treated with PD (5-year HR 0.38, 95 % CI 0.15-0.96). PD was not associated with impaired prognosis in any of the prespecified subgroups compared to HD. The results were similar in the as-treated and intention-to-treat analyses.
  
  
  CONCLUSIONS
  Survival in PD was not inferior to HD in any subgroup of patients even after five years of follow-up. In patients below 65 years, PD yielded superior survival rates compared to HD. Increased use of PD as initial dialysis modality in ESRD patients could be encouraged.
authors.affiliation: Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway. bard.waldum@medisin.uio.no.|Department of Nephrology, Oslo University Hospital, PB 4956 Nydalen, N-0424, Oslo, Norway. bard.waldum@medisin.uio.no.
authors.forename: Bård
authors.initials: B
authors.lastname: Waldum-Grevbo
authors.affiliation: Norwegian Renal Registry, Department of Transplantation Medicine, Oslo University Hospital, Oslo, Norway. tleivest@ous-hf.no.
authors.forename: Torbjørn
authors.initials: T
authors.lastname: Leivestad
authors.affiliation: Norwegian Renal Registry, Department of Transplantation Medicine, Oslo University Hospital, Oslo, Norway. areisate@ous-hf.no.|Section of Nephrology, Department of Transplantation Medicine, Oslo University Hospital, Oslo, Norway. areisate@ous-hf.no.
authors.forename: Anna V
authors.initials: AV
authors.lastname: Reisæter
authors.affiliation: Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway. ingrid.os@medisin.uio.no.|Department of Nephrology, Oslo University Hospital, PB 4956 Nydalen, N-0424, Oslo, Norway. ingrid.os@medisin.uio.no.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Os
mesh_terms: D017677:Age Distribution; D002318:Cardiovascular Diseases / Q000401:mortality*; D015897:Comorbidity; D003956:Dialysis; D005260:Female; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000401:mortality* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D057216:Propensity Score; D012042:Registries; D006435:Renal Dialysis / Q000401:mortality* / Q000706:statistics & numerical data*; D012307:Risk Factors; D017678:Sex Distribution; D015996:Survival Rate; D016896:Treatment Outcome