title: Body mass index and mortality in heart failure: a meta-analysis.
abstract: BACKGROUND
  In patients with chronic heart failure (CHF), previous studies have reported reduced mortality rates in patients with increased body mass index (BMI). The potentially protective effect of increased BMI in CHF has been termed the obesity paradox or reverse epidemiology. This meta-analysis was conducted to examine the relationship between increased BMI and mortality in patients with CHF.
  
  
  METHODS
  We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Scopus, and Web of Science to identify studies with contemporaneous control groups (cohort, case-control, or randomized controlled trials) that examined the effect of obesity on all-cause and cardiovascular mortality. Two reviewers independently assessed studies for inclusion and performed data extraction.
  
  
  RESULTS
  Nine observational studies met final inclusion criteria (total n = 28,209). Mean length of follow-up was 2.7 years. Compared to individuals without elevated BMI levels, both overweight (BMI approximately 25.0-29.9 kg/m(2), RR 0.84, 95% CI 0.79-0.90) and obesity (BMI approximately > or =30 kg/m(2), RR 0.67, 95% CI 0.62-0.73) were associated with lower all-cause mortality. Overweight (RR 0.81, 95% CI 0.72-0.92) and obesity (RR 0.60, 95% CI 0.53-0.69) were also associated with lower cardiovascular mortality. In a risk-adjusted sensitivity analysis, both obesity (adjusted HR 0.88, 95% CI 0.83-0.93) and overweight (adjusted HR 0.93, 95% CI 0.89-0.97) remained protective against mortality.
  
  
  CONCLUSIONS
  Overweight and obesity were associated with lower all-cause and cardiovascular mortality rates in patients with CHF and were not associated with increased mortality in any study. There is a need for prospective studies to elucidate mechanisms for this relationship.
authors.affiliation: Department of Clinical Epidemiology, School of Public Health, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Antigone
authors.initials: A
authors.lastname: Oreopoulos
authors.forename: Raj
authors.initials: R
authors.lastname: Padwal
authors.forename: Kamyar
authors.initials: K
authors.lastname: Kalantar-Zadeh
authors.forename: Gregg C
authors.initials: GC
authors.lastname: Fonarow
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Norris
authors.forename: Finlay A
authors.initials: FA
authors.lastname: McAlister
mesh_terms: D015992:Body Mass Index; D002423:Cause of Death; D005260:Female; D006333:Heart Failure / Q000401:mortality*; D006801:Humans; D008297:Male; D009765:Obesity / Q000150:complications*; D011379:Prognosis; D012016:Reference Values; D018570:Risk Assessment; D016019:Survival Analysis