title: First-ever atrial fibrillation documented after hemorrhagic or ischemic stroke: the role of the CHADS(2) score at the time of stroke.
abstract: BACKGROUND
  The CHADS(2) score (C, congestive heart failure [CHF]; H, hypertension [HT]; A, age ≥75 y; D, diabetes mellitus; S(2) , prior stroke or transient ischemic attack) is used to assess the risk of ischemic stroke in patients with atrial fibrillation (AF). However, its role in patients without documented AF is not well explored.
  
  
  OBJECTIVE
  The goal of the current study was to explore if the incidence of hospitalization with first-ever AF after stroke increased with increasing CHADS(2) score.
  
  
  METHODS
  We identified 57636 patients with nonfatal stroke and no documented AF in the Swedish Stroke Register (Riks-Stroke) during 2001-2004 and followed them for a mean of 2.2 years through record linkage to the Inpatient and Cause of Death registers. Cox regression hazard models were used to estimate the relative risk (RR) of new AF following stroke and its association with different CHADS(2) scores.
  
  
  RESULTS
  Overall, 2769 patients were hospitalized with new AF (4.8%, 21.7 per 1000 person-years). The incidence increased from 9.6 per 1000 person-years in CHADS(2) score 0 to 42.7 in CHADS(2) score 6, conferring a RR of 4.2 (95% confidence interval [CI]: 2.5-6.8). For CHADS(2) scores 3-5, the RRs were approximately 3 (vs CHADS(2) score 0). Adjusted RRs were 1.9 (95% CI: 1.7-2.1) for CHF, 1.4 (95% CI: 1.3-1.5) for HT, 2.1 (95% CI: 2.0-2.3) for age ≥75 years, 0.9 (95% CI: 0.8-1.0) for diabetes, and 1.0 (95% CI: 0.91-1.07) for previous stroke. The risk of AF was higher in ischemic than in hemorrhagic stroke.
  
  
  CONCLUSIONS
  In this retrospective register study, the incidence of AF following stroke was strongly influenced by higher CHADS(2) scores where age ≥75 years, CHF, and HT were the contributing CHADS(2) components.
authors.affiliation: AstraZeneca, Epidemiology R&D, Sweden; Department of Laboratory Medicine, Lund University, Lund, Sweden. karin.henriksson@astrazeneca.com
authors.forename: Karin M
authors.initials: KM
authors.lastname: Henriksson
authors.forename: Bahman
authors.initials: B
authors.lastname: Farahmand
authors.forename: Signild
authors.initials: S
authors.lastname: Asberg
authors.forename: Andreas
authors.initials: A
authors.lastname: Terént
authors.forename: Nils
authors.initials: N
authors.lastname: Edvardsson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology*; D002545:Brain Ischemia / Q000150:complications* / Q000175:diagnosis; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012042:Registries; D012189:Retrospective Studies; D012306:Risk; D020521:Stroke / Q000150:complications* / Q000175:diagnosis; D013548:Sweden; D013997:Time Factors