title: Atrial fibrillation risk in metabolically healthy obesity: A nationwide population-based study.
abstract: BACKGROUND
  Metabolically healthy obese (MHO) individuals are reported to have a marginal increase in cardiovascular risk; however, their atrial fibrillation (AF) risk is unclear. We aimed to assess AF risk in MHO individuals and identify whether AF development is associated with obesity or influenced by metabolic comorbidities.
  
  
  METHODS
  A retrospective cohort of 389,321 individuals (age, 45.6±14.5years; male, 52.1%) was extracted from the Korean National Health Insurance sample database between 2004 and 2006 and followed-up for new-onset AF until 2013. Subjects with diabetes mellitus, hypertension, and/or dyslipidemia were classified as "metabolically unhealthy." The cohort was stratified into four groups according to obesity and metabolic healthiness: metabolically healthy non-obese (MHNO), metabolically unhealthy non-obese (MUNO), MHO, and metabolically unhealthy obese (MUO).
  
  
  RESULTS
  AF was newly diagnosed in 5106 (1.3%) individuals during a mean follow-up of 7.5±1.5years. The AF incidence rates for the MHNO, MUNO, MHO, and MUO groups were 0.76, 2.66, 1.10, and 2.88 per 1000 person-years, respectively. Compared with the MHNO group, the MHO group had increased AF risk (adjusted hazard ratio, 1.30; 95% CI, 1.14-1.48) on multivariate analysis. One fourth of the MHO cohort became metabolically unhealthy, contributing to increased AF risk. Obesity was an independent risk factor for AF, and increased AF risk by 20%. Metabolic unhealthiness increased AF risk by around 40%, and of its components, hypertension contributed the most.
  
  
  CONCLUSIONS
  MHO individuals are at increased risk for AF development, and obesity was independently associated with elevated AF risk.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: HyunJung
authors.initials: H
authors.lastname: Lee
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea. Electronic address: choiek17@snu.ac.kr.
authors.forename: Eue-Keun
authors.initials: EK
authors.lastname: Choi
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. Electronic address: hwanx2@catholic.ac.kr.
authors.forename: Seung-Hwan
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Biostatistics, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Kyung-Do
authors.initials: KD
authors.lastname: Han
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Tae-Min
authors.initials: TM
authors.lastname: Rhee
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Chan-Soon
authors.initials: CS
authors.lastname: Park
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: So-Ryoung
authors.initials: SR
authors.lastname: Lee
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Won-Seok
authors.initials: WS
authors.lastname: Choe
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Seoul National University Boramae Medical Center, Seoul, Republic of Korea.
authors.forename: Woo-Hyun
authors.initials: WH
authors.lastname: Lim
authors.affiliation: Department of Cardiology, Cardiovascular Center, Seoul National University Bundang Hospital, Seongnam-si, Republic of Korea.
authors.forename: Si-Hyuck
authors.initials: SH
authors.lastname: Kang
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Myung-Jin
authors.initials: MJ
authors.lastname: Cha
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Seil
authors.initials: S
authors.lastname: Oh
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D000067329:Obesity, Metabolically Benign / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D011159:Population Surveillance / Q000379:methods; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Atrial fibrillation; Epidemiology; Metabolically healthy obesity; Obesity; Risk factors