title: Caffeine intake and atrial fibrillation incidence: dose response meta-analysis of prospective cohort studies.
abstract: BACKGROUND
  The association between habitual caffeine intake with incident atrial fibrillation (AF) was unknown. We conducted a meta-analysis to investigate the association between chronic exposure of caffeine and the risk of AF and to evaluate the potential dose-response relation.
  
  
  METHODS
  We searched PubMed, EMBASE, and the Cochrane Library up to November 2013 and references of relevant retrieved articles. Prospective cohort studies were included with relative risk (RR) or hazard ratio and 95% confidence intervals (CIs) for AF according to coffee/caffeine intake.
  
  
  RESULTS
  Six prospective cohort studies with 228,465 participants were included. In the primary meta-analysis, caffeine exposure was weakly associated with a reduced risk of AF (RR, 0.90; 95% CI, 0.81-1.01; P = 0.07; I(2) = 73%). In subgroup analyses, pooled results from studies with adjustment of potential confounders showed an 11% reduction for low doses (RR, 0.89; 95% CI, 0.80-0.99, P = 0.032; I(2) = 30.9%, P = 0.227) and 16% for high doses (RR, 0.84; 95% CI, 0.75-0.94, P = 0.002; I(2) = 24.1%, P = 0.267) of caffeine consumption in AF risk. An inverse relation was found between habitual caffeine intake and AF risk (P for overall trend = 0.015; P for nonlinearity = 0.27) in dose-response meta-analysis and the incidence of AF decreased by 6% (RR, 0.94; 95% CI, 0.90-0.99) for every 300 mg/d increment in habitual caffeine intake.
  
  
  CONCLUSIONS
  It is unlikely that caffeine consumption causes or contributes to AF. Habitual caffeine consumption might reduce AF risk.
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Min
authors.initials: M
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Zunsong
authors.initials: Z
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Xiangfeng
authors.initials: X
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. Electronic address: gudongfeng@vip.sina.com.
authors.forename: Dongfeng
authors.initials: D
authors.lastname: Gu
mesh_terms: D001281:Atrial Fibrillation / Q000517:prevention & control*; D002110:Caffeine / Q000008:administration & dosage*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015994:Incidence; D011446:Prospective Studies
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine