title: Increased risk of first-ever stroke in younger patients with atrial fibrillation not recommended for antithrombotic therapy by current guidelines: a population-based study in an East Asian cohort of 22 million people.
abstract: OBJECTIVE
  To assess the risk of first-ever ischemic stroke in younger patients with atrial fibrillation (AF) who have none of the CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, previous stroke/transient ischemic attack, vascular disease, age 65-74 years, sex category [female sex]) risk factors (excluding female sex) by using the National Health Insurance research database in Taiwan.
  
  
  METHODS
  From 22,842,778 insured people, we identified 24,612 hospitalized patients with newly diagnosed AF between January 1, 2002, and December 31, 2004, as the AF group and randomly selected 98,448 age- and sex-matched persons without AF as the non-AF group. Both groups were followed up until December 31, 2010, to estimate ischemic stroke incidences in relation to other stroke risk factors.
  
  
  RESULTS
  During a follow-up period of 89,468 person-years, the stroke rate was higher in patients with AF than in those without AF (5.79 per 100 person-years vs 2.25 per 100 person-years). The higher prevalence of CHA2DS2-VASc comorbidities (heart failure, hypertension, diabetes, coronary artery disease, and peripheral artery disease) in patients with AF further increased the stroke risk. In 790 patients with AF aged 30 to 55 years who had none of the CHA2DS2-VASc comorbidities at baseline and retained a "low risk," that is, those with a CHA2DS2-VASc score of 0 in men and 1 in women during follow-up, the stroke rate remained considerably higher than that in their non-AF counterparts (1.00 per 100 person-years vs 0.25 per 100 person-years), with a sex-adjusted hazard ratio of 4.09 (95% CI, 2.97-5.62).
  
  
  CONCLUSIONS
  This study finds an increased risk of stroke in younger patients with AF who are not recommended for prevention of thromboembolism by current guidelines. Better stroke risk stratification tools are needed to prioritize younger patients with AF for thromboprophylactic therapy in this population.
authors.affiliation: Division of Cardiology, Department of Medicine, China Medical University Hospital, Taichung, Taiwan; Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.
authors.forename: Kuan-Cheng
authors.initials: KC
authors.lastname: Chang
authors.affiliation: Division of Cardiology, Department of Medicine, China Medical University Hospital, Taichung, Taiwan; Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.
authors.forename: Yu-Chen
authors.initials: YC
authors.lastname: Wang
authors.affiliation: Division of Cardiology, Department of Medicine, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Po-Yen
authors.initials: PY
authors.lastname: Ko
authors.affiliation: Division of Cardiology, Department of Medicine, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Hung-Pin
authors.initials: HP
authors.lastname: Wu
authors.affiliation: Department of Neurology, Landseed Hospital, Taoyuan, Taiwan.
authors.forename: Yu-Wei
authors.initials: YW
authors.lastname: Chen
authors.affiliation: Department of Public Health, China Medical University, Taichung, Taiwan; China Medical University Hospital Management Office for Health Data, Taichung, Taiwan.
authors.forename: Chih-Hsin
authors.initials: CH
authors.lastname: Muo
authors.affiliation: Department of Public Health, China Medical University, Taichung, Taiwan.
authors.forename: Fung-Chang
authors.initials: FC
authors.lastname: Sung
authors.affiliation: Graduate Institute of Biostatistics, China Medical University, Taichung, Taiwan.
authors.forename: Tsai-Chung
authors.initials: TC
authors.lastname: Li
authors.affiliation: Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan; Department of Public Health, China Medical University, Taichung, Taiwan. Electronic address: hsucy63141@gmail.com.
authors.forename: Chung Y
authors.initials: CY
authors.lastname: Hsu
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001281:Atrial Fibrillation / Q000150:complications / Q000188:drug therapy*; D015897:Comorbidity; D005260:Female; D005343:Fibrinolytic Agents / Q000592:standards* / Q000627:therapeutic use; D006801:Humans; D015994:Incidence; D007345:Insurance Claim Review; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D017410:Practice Guidelines as Topic; D015995:Prevalence; D012189:Retrospective Studies; D018570:Risk Assessment; D020521:Stroke / Q000209:etiology / Q000517:prevention & control*; D013624:Taiwan / Q000453:epidemiology
chemical_list: D005343:Fibrinolytic Agents