title: Association of morbid obesity and weight change over time with cardiovascular survival in hemodialysis population.
abstract: BACKGROUND
  In maintenance hemodialysis (MHD) outpatients, a reverse epidemiology is described, ie, baseline obesity appears paradoxically associated with improved survival. However, the association between changes in weight over time and prospective mortality is not known.
  
  
  METHODS
  Using time-dependent Cox models and adjusting for changes in laboratory values over time, the relation of quarterly-varying 3-month averaged body mass index (BMI) to all-cause and cardiovascular mortality was examined in a 2-year cohort of 54,535 MHD patients from virtually all DaVita dialysis clinics in the United States.
  
  
  RESULTS
  Patients, aged 61.7 +/- 15.5 (SD) years, included 54% men and 45% with diabetes. Time-dependent unadjusted and multivariate-adjusted models, based on quarterly-averaged BMI controlled for case-mix and available time-varying laboratory surrogates of nutritional status, were calculated in 11 categories of BMI. Obesity, including morbid obesity, was associated with better survival and reduced cardiovascular death, even after accounting for changes in BMI and laboratory values over time. Survival advantages of obesity were maintained for dichotomized BMI cutoff values of 25, 30, and 35 kg/m2 across almost all strata of age, race, sex, dialysis dose, protein intake, and serum albumin level. Examining the regression slope of change in weight over time, progressively worsening weight loss was associated with poor survival, whereas weight gain showed a tendency toward decreased cardiovascular death.
  
  
  CONCLUSIONS
  Weight gain and both baseline and time-varying obesity may be associated with reduced cardiovascular mortality in MHD patients independent of laboratory surrogates of nutritional status and their changes over time. Morbidly obese patients have the lowest mortality. Clinical trials need to verify these observational findings.
authors.affiliation: Division of Nephrology and Hypertension, Los Angeles Biomedical Institute, Harbor-UCLA Medical Center, Torrance, CA 90509-2910, USA. kamkal@ucla.edu
authors.forename: Kamyar
authors.initials: K
authors.lastname: Kalantar-Zadeh
authors.forename: Joel D
authors.initials: JD
authors.lastname: Kopple
authors.forename: Ryan D
authors.initials: RD
authors.lastname: Kilpatrick
authors.forename: Charles J
authors.initials: CJ
authors.lastname: McAllister
authors.forename: Christian S
authors.initials: CS
authors.lastname: Shinaberger
authors.forename: David W
authors.initials: DW
authors.lastname: Gjertson
authors.forename: Sander
authors.initials: S
authors.lastname: Greenland
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000401:mortality*; D002423:Cause of Death; D015331:Cohort Studies; D015897:Comorbidity; D003920:Diabetes Mellitus / Q000453:epidemiology; D005006:Ethnicity / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007249:Inflammation / Q000453:epidemiology; D007676:Kidney Failure, Chronic / Q000453:epidemiology* / Q000628:therapy; D008297:Male; D044342:Malnutrition / Q000453:epidemiology; D008875:Middle Aged; D009026:Mortality; D009767:Obesity, Morbid / Q000453:epidemiology*; D016016:Proportional Hazards Models; D006435:Renal Dialysis; D012959:Socioeconomic Factors; D016019:Survival Analysis; D015430:Weight Gain; D015431:Weight Loss
chemical_list: D015415:Biomarkers