title: Risks for stroke and bleeding with warfarin or aspirin treatment in patients with atrial fibrillation at different CHA(2)DS(2)VASc scores: experience from the Stockholm region.
abstract: OBJECTIVE
  This study evaluated the benefits of and possible contraindications to warfarin treatment in patients with atrial fibrillation (AF) prior to the introduction of new oral anticoagulants using health registry data from inpatient care, specialist ambulatory care, and primary care.
  
  
  METHODS
  This is a cohort study including all patients in the region of Stockholm, Sweden (2.1 million inhabitants) with a diagnosis of non-valvular AF (n = 41 810) recorded during 2005-2009. The risks of suffering ischemic stroke, bleeding, or death with warfarin, aspirin, or no antithrombotic treatment during 2010 were related to CHA2DS2VASc scores, age, and complicating co-morbidities.
  
  
  RESULTS
  One-year risks for ischemic stroke were 1.0-1.2 % with aspirin, 0-0.3 % with warfarin, and 0.1-0.2 % without treatment at CHA2DS2VASc scores 0-1. Among the aspirin-treated patients with CHA2DS2VASc scores ≥2, half had possible contraindications and high risks for ischemic stroke (5.2 %), bleeding (5.0 %), and death (19.3 %). The other half of the patients with no identified contraindications had a high risk for ischemic stroke (4.0 %) but a low bleeding risk (1.8 %) and a moderate mortality rate (8.4 %).
  
  
  CONCLUSIONS
  The present observations confirm earlier findings of undertreatment with warfarin and half of the high-risk patients treated with aspirin were obvious candidates for anticoagulant treatment. However, the other half of the patients had complicating co-morbidities, high bleeding risk, and poor prognosis. This and possible overtreatment of low-risk patients should be taken into account when considering more aggressive use of anticoagulant treatment.
authors.affiliation: Department of Medicine Solna, Clinical Pharmacology Unit, Karolinska University Hospital, Karolinska Institutet, 171 76, Stockholm, Sweden, tomas.forslund@sll.se.
authors.forename: Tomas
authors.initials: T
authors.lastname: Forslund
authors.forename: Björn
authors.initials: B
authors.lastname: Wettermark
authors.forename: Per
authors.initials: P
authors.lastname: Wändell
authors.forename: Mia
authors.initials: M
authors.lastname: von Euler
authors.forename: Jan
authors.initials: J
authors.lastname: Hasselström
authors.forename: Paul
authors.initials: P
authors.lastname: Hjemdahl
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects*; D001241:Aspirin / Q000009:adverse effects*; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced / Q000453:epidemiology*; D006801:Humans; D008297:Male; D012306:Risk; D020521:Stroke / Q000139:chemically induced / Q000453:epidemiology*; D013548:Sweden / Q000453:epidemiology; D013923:Thromboembolism / Q000517:prevention & control; D014859:Warfarin / Q000009:adverse effects*
chemical_list: D000925:Anticoagulants; D014859:Warfarin; D001241:Aspirin