title: Overweight is associated with improved survival and outcomes in patients with atrial fibrillation.
abstract: BACKGROUND
  The aim of this study was to investigate the association of body mass index (BMI) with mortality and cardiovascular events in Chinese patients with atrial fibrillation (AF).
  
  
  RESULTS
  This study consecutively enrolled AF patients presenting to an emergency department at 20 hospitals in China from November 2008 to October 2011. A total of 2,016 AF patients was enrolled, and patients were categorized as underweight (BMI <18.5), normal (BMI 18.5 to <24), overweight (BMI 24 to <28), and obese (BMI ≥ 28 all kg/m(2)). Multivariate Cox proportional hazards regression was used on all the patients. End points of the analyses were all-cause mortality, cardiovascular mortality, and combined end events. Among overall patients, mean BMI was 23.5 ± 3.6 kg/m(2); 279 (13.8 %) patients died during 12-month follow-up, and so did 23.2 % underweight, 16.3, 9.5 and 9.2 % normal weight, overweight, and obese patients, respectively (P < 0.001). Cardiovascular mortality was 8.3% in all patients, and in underweight, normal weight, overweight and obese categories were 16.5, 9.0, 5.4 and 6.9 %, respectively (P < 0.001). On multivariate analysis, as continuous variable, BMI was not a risk factor for all-cause mortality in AF patients (hazard ratio [HR] 0.94; 95 % confidence interval [CI] 0.91-0.97; P = 0.001). As categorical variable, underweight (HR 1.57, 95 % CI 1.02-2.42, P = 0.041) and normal weight (HR 1.53, 95 % CI 1.13-2.06, P = 0.005) categories were associated with higher all-cause mortality as compared with overweight category. Underweight (HR 2.01, 95 % CI 1.76-3.43, P = 0.011) and normal weight patients (HR 1.53, 95 % CI 1.03-2.28, P = 0.037) also had higher cardiovascular mortality as compared with the overweight category.
  
  
  CONCLUSIONS
  Obesity and overweight were not risk factors for 12-month mortality in Chinese AF patients. Overweight AF patients have better survival and outcomes than normal weight (BMI 18.5-24 kg/m(2)) and underweight patients.
authors.affiliation: Emergency and Intensive Care Center, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, 100037, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
authors.forename: Yan-min
authors.initials: YM
authors.lastname: Yang
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.forename: Xing-hui
authors.initials: XH
authors.lastname: Shao
authors.forename: Li
authors.initials: L
authors.lastname: Tian
authors.forename: Bi
authors.initials: B
authors.lastname: Huang
authors.forename: Li-tian
authors.initials: LT
authors.lastname: Yu
authors.forename: Xin
authors.initials: X
authors.lastname: Gao
authors.forename: Man
authors.initials: M
authors.lastname: Wang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000453:epidemiology* / Q000401:mortality; D015992:Body Mass Index; D002681:China / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D056865:Ideal Body Weight; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009765:Obesity / Q000453:epidemiology*; D050177:Overweight / Q000453:epidemiology*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D015996:Survival Rate; D013851:Thinness / Q000453:epidemiology*