title: Obesity, physical activity, and their interaction in incident atrial fibrillation in postmenopausal women.
abstract: BACKGROUND
  Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with increased risk of stroke and death. Obesity is an independent risk factor for AF, but modifiers of this risk are not well known. We studied the roles of obesity, physical activity, and their interaction in conferring risk of incident AF.
  
  
  RESULTS
  The Women's Health Initiative (WHI) Observational Study was a prospective observational study of 93 676 postmenopausal women followed for an average of 11.5 years. Incident AF was identified using WHI-ascertained hospitalization records and diagnostic codes from Medicare claims. A multivariate Cox's hazard regression model adjusted for demographic and clinical risk factors was used to evaluate the interaction between obesity and physical activity and its association with incident AF. After exclusion of women with prevalent AF, incomplete data, or underweight body mass index (BMI), 9792 of the remaining 81 317 women developed AF. Women were, on average, 63.4 years old, 7.8% were African American, and 3.6% were Hispanic. Increased BMI (hazard ratio [HR], 1.12 per 5-kg/m(2) increase; 95% confidence interval [CI], 1.10 to 1.14) and reduced physical activity (>9 vs. 0 metabolic equivalent task hours per week; HR, 0.90; 95% CI, 0.85 to 0.96) were independently associated with higher rates of AF after multivariate adjustment. Higher levels of physical activity reduced the AF risk conferred by obesity (interaction P=0.033).
  
  
  CONCLUSIONS
  Greater physical activity is associated with lower rates of incident AF and modifies the association between obesity and incident AF.
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA (F.A., T.L.A., M.A.H., M.V.P.).
authors.forename: Farnaz
authors.initials: F
authors.lastname: Azarbal
authors.affiliation: Department of Medicine, Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, CA (M.L.S.).
authors.forename: Marcia L
authors.initials: ML
authors.lastname: Stefanick
authors.affiliation: Department of Medicine, Brown University School of Medicine, Providence, RI (E.S.B.).
authors.forename: Elena
authors.initials: E
authors.lastname: Salmoirago-Blotcher
authors.affiliation: Division of Preventive Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (J.A.E.M., C.M.A.).
authors.forename: JoAnn E
authors.initials: JE
authors.lastname: Manson
authors.affiliation: Division of Preventive Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (J.A.E.M., C.M.A.) Division of Cardiology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (C.M.A.).
authors.forename: Christine M
authors.initials: CM
authors.lastname: Albert
authors.affiliation: Department of Social and Prevention Medicine, School of Public Health and Health Professions, University of Buffalo, Buffalo, NY (M.J.L.M.).
authors.forename: Michael J
authors.initials: MJ
authors.lastname: LaMonte
authors.affiliation: Data Coordinating Center, Fred Hutchinson Cancer Research Center, Seattle, WA (J.C.L.).
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Larson
authors.affiliation: Division of Preventive and Behavioral Medicine, University of Massachusetts Medical School, Worcester, MA (W.L.).
authors.forename: Wenjun
authors.initials: W
authors.lastname: Li
authors.affiliation: School of Medicine and Health Sciences, George Washington University, Washington, DC (L.W.M.).
authors.forename: Lisa W
authors.initials: LW
authors.lastname: Martin
authors.affiliation: Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, CA (R.N.).
authors.forename: Rami
authors.initials: R
authors.lastname: Nassir
authors.affiliation: Department of Public Health Sciences, University of California Davis, Davis, CA (L.G.).
authors.forename: Lorena
authors.initials: L
authors.lastname: Garcia
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA (F.A., T.L.A., M.A.H., M.V.P.).
authors.forename: Themistocles L
authors.initials: TL
authors.lastname: Assimes
authors.affiliation: Institutional Research and Assessment, Loras College, Dubuque, IA (K.M.T.).
authors.forename: Katie M
authors.initials: KM
authors.lastname: Tharp
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA (F.A., T.L.A., M.A.H., M.V.P.) Department of Health Research and Policy, Stanford University School of Medicine, Stanford, CA (M.A.H.).
authors.forename: Mark A
authors.initials: MA
authors.lastname: Hlatky
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA (F.A., T.L.A., M.A.H., M.V.P.).
authors.forename: Marco V
authors.initials: MV
authors.lastname: Perez
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000453:epidemiology*; D002318:Cardiovascular Diseases / Q000453:epidemiology; D003920:Diabetes Mellitus / Q000453:epidemiology; D015444:Exercise; D005260:Female; D006801:Humans; D006949:Hyperlipidemias / Q000453:epidemiology; D006973:Hypertension / Q000453:epidemiology*; D015994:Incidence; D008137:Longitudinal Studies; D008875:Middle Aged; D009043:Motor Activity; D009765:Obesity / Q000453:epidemiology*; D050177:Overweight / Q000453:epidemiology; D017698:Postmenopause; D011446:Prospective Studies; D012307:Risk Factors; D057185:Sedentary Behavior
keywords: atrial fibrillation; electrophysiology; epidemiology; exercise; obesity