title: Increased risk of stroke after discontinuation of acetylsalicylic acid: a UK primary care study.
abstract: OBJECTIVE
  Discontinuation of low-dose acetylsalicylic acid (ASA) therapy may increase the risk of ischemic events. This study evaluated the risk of ischemic stroke (IS) and TIA after low-dose ASA discontinuation in patients with cardiovascular disease or cerebrovascular disease.
  
  
  METHODS
  The Health Improvement Network UK primary care database was used to identify a cohort of individuals aged 50-84 years with a first prescription for low-dose ASA (75-300 mg/day) for the secondary prevention of cardiovascular or cerebrovascular events in 2000-2007 (n = 39,512). Individuals were followed up for a mean of 3.4 years to identify cases of IS/TIA. Nested case-control analyses were used to assess risk factors for IS/TIA, including low-dose ASA discontinuation.
  
  
  RESULTS
  The overall incidence of IS/TIA was 5.0 per 1,000 person-years (95% confidence interval [CI] 4.6-5.4). IS/TIA was significantly more common in patients with a previous diagnosis of cerebrovascular disease (relative risk [RR] 2.79; 95% CI 2.05-3.80) or atrial fibrillation (RR 1.71; 95% CI 1.28-2.29) than in those without these conditions. Compared with current users of low-dose ASA, those who discontinued treatment 31-180 days before the index date had a significantly increased overall risk of IS/TIA (RR 1.40; 95% CI 1.03-1.92). The most common reason for discontinuation was patient nonadherence.
  
  
  CONCLUSIONS
  In patients prescribed low-dose ASA for the secondary prevention of cardiovascular or cerebrovascular events, discontinuation of low-dose ASA was associated with a 40% increase in the risk of IS/TIA compared with continuation of therapy.
  
  
  METHODS
  This study provides Class III evidence that discontinuation of low-dose ASA is associated with a 40% increased risk of stroke within 31-180 days of discontinuation.
authors.affiliation: Spanish Centre for Pharmacoepidemiologic Research (CEIFE), Madrid 28004, Spain. lagarcia@ceife.es
authors.forename: Luis A
authors.initials: LA
authors.lastname: García Rodríguez
authors.forename: Lucía
authors.initials: L
authors.lastname: Cea Soriano
authors.forename: Catherine
authors.initials: C
authors.lastname: Hill
authors.forename: Saga
authors.initials: S
authors.lastname: Johansson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000009:adverse effects*; D002318:Cardiovascular Diseases / Q000517:prevention & control; D002561:Cerebrovascular Disorders / Q000517:prevention & control; D015331:Cohort Studies; D005260:Female; D005343:Fibrinolytic Agents / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data*; D011320:Primary Health Care / Q000706:statistics & numerical data; D012307:Risk Factors; D020521:Stroke / Q000139:chemically induced* / Q000453:epidemiology*; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D005343:Fibrinolytic Agents; D001241:Aspirin