title: Estimating population attributable fractions to quantify the health burden of obesity.
abstract: OBJECTIVE
  Obesity is a highly prevalent condition in the United States and elsewhere and is associated with increased mortality and morbidity. Here, we discuss some issues involved in quantifying the health burden of obesity using population attributable fraction (PAF) estimates and provide examples.
  
  
  METHODS
  We searched PubMed for articles reporting attributable fraction estimates for obesity. We reviewed eligible articles to identify methodological concerns and tabulated illustrative examples of PAF estimates for obesity relative to cancer, diabetes, cardiovascular disease, and all-cause mortality.
  
  
  RESULTS
  There is considerable variability among studies regarding the methods used for PAF calculation and the selection of appropriate counterfactuals. The reported estimates ranged from 5% to 15% for all-cause mortality, -0.2% to 8% for all-cancer incidence, 7% to 44% for cardiovascular disease incidence, and 3% to 83% for diabetes incidence.
  
  
  CONCLUSIONS
  To evaluate a given estimate, it is important to consider whether the exposure and outcome were defined similarly for the PAF and for the relative risks, whether the relative risks were suitable for the population at hand, and whether PAF was calculated using correct methods. Strong causal assumptions are not necessarily warranted. In general, PAFs for obesity may be best considered as indicators of association.
authors.affiliation: Centers for Disease Control and Prevention, National Center for Health Statistics, Hyattsville, MD. Electronic address: kmf2@cdc.gov.
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Flegal
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD.
authors.forename: Orestis A
authors.initials: OA
authors.lastname: Panagiotou
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD.
authors.forename: Barry I
authors.initials: BI
authors.lastname: Graubard
mesh_terms: D015992:Body Mass Index; D001835:Body Weight; D017281:Cost of Illness; D004812:Epidemiologic Methods; D006801:Humans; D015994:Incidence; D008297:Male; D009765:Obesity / Q000453:epidemiology* / Q000523:psychology; D011159:Population Surveillance; D015995:Prevalence; D012306:Risk; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
keywords: Body mass index; Body weight; Epidemiologic methods; Obesity; Risk