title: The association between body mass index and mortality in incident dialysis patients.
abstract: OBJECTIVE
  To study the body mass index (BMI) trajectory in patients with incident end-stage kidney disease and its association with all-cause mortality.
  
  
  METHODS
  This longitudinal cohort study included 17022 adult patients commencing hemodialysis [HD] (n = 10860) or peritoneal dialysis [PD] (n = 6162) between 2001 and 2008 and had ≥6-month follow-up and ≥2 weight measurements, using the Australia and New Zealand Dialysis and Transplant Registry data. The association of time-varying BMI with all-cause mortality was explored using multivariate Cox regression models.
  
  
  RESULTS
  The median follow-up was 2.3 years. There was a non-linear change in the mean BMI (kg/m2) over time, with an initial decrease from 27.6 (95% confidence interval [CI]: 27.5, 27.7) to 26.7 (95% CI: 26.6, 26.9) at 3-month, followed by increments to 27.1 (95% CI: 27, 27.2) at 1-year and 27.2 (95% CI: 26.8, 27.1) at 3-year, and a gradual decrease subsequently. The BMI trajectory was significantly lower in HD patients who died than those who survived, although this pattern was not observed in PD patients. Compared to the reference time-varying BMI category of 25.1-28 kg/m2, the mortality risks of both HD and PD patients were greater in all categories of time-varying BMI <25 kg/m2. The mortality risks were significantly lower in all categories of time-varying BMI >28.1 kg/m2 among HD patients, but only in the category 28.1-31 kg/m2 among PD patients.
  
  
  CONCLUSIONS
  BMI changed over time in a non-linear fashion in incident dialysis patients. Time-varying measures of BMI were significantly associated with mortality risk in both HD and PD patients.
authors.affiliation: Department of Nephrology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
authors.forename: Sunil V
authors.initials: SV
authors.lastname: Badve
authors.affiliation: Clinical Trials & Biostatistics Unit, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Sanjoy K
authors.initials: SK
authors.lastname: Paul
authors.affiliation: Clinical Trials & Biostatistics Unit, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Kerenaftali
authors.initials: K
authors.lastname: Klein
authors.affiliation: Department of Renal Medicine, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Clayton
authors.affiliation: Department of Nephrology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
authors.forename: Carmel M
authors.initials: CM
authors.lastname: Hawley
authors.affiliation: Department of Nephrology & Medicine, Monash Medical Centre and Monash University, Melbourne, Victoria, Australia.
authors.forename: Fiona G
authors.initials: FG
authors.lastname: Brown
authors.affiliation: School of Medicine and Pharmacology, University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Neil
authors.initials: N
authors.lastname: Boudville
authors.affiliation: Department of Nephrology & Medicine, Monash Medical Centre and Monash University, Melbourne, Victoria, Australia.
authors.forename: Kevan R
authors.initials: KR
authors.lastname: Polkinghorne
authors.affiliation: Australia and New Zealand Dialysis and Transplant Registry, University of Adelaide at Central Northern Adelaide Renal & Transplant Services, Adelaide, South Australia, Australia.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: McDonald
authors.affiliation: Department of Nephrology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
authors.forename: David W
authors.initials: DW
authors.lastname: Johnson
mesh_terms: D000328:Adult; D000368:Aged; D001315:Australia; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D009765:Obesity / Q000473:pathology; D012042:Registries; D006435:Renal Dialysis / Q000706:statistics & numerical data*; D012306:Risk; D012307:Risk Factors; D055815:Young Adult