title: Discontinuation of low dose aspirin and risk of myocardial infarction: case-control study in UK primary care.
abstract: OBJECTIVE
  To evaluate the risk of myocardial infarction and death from coronary heart disease after discontinuation of low dose aspirin in primary care patients with a history of cardiovascular events.
  
  
  METHODS
  Nested case-control study.
  
  
  METHODS
  The Health Improvement Network (THIN) database in the United Kingdom.
  
  
  METHODS
  Individuals aged 50-84 with a first prescription for aspirin (75-300 mg/day) for secondary prevention of cardiovascular outcomes in 2000-7 (n=39,513).
  
  
  METHODS
  Individuals were followed up for a mean of 3.2 years to identify cases of non-fatal myocardial infarction or death from coronary heart disease. A nested case-control analysis assessed the risk of these events in those who had stopped taking low dose aspirin compared with those who had continued treatment.
  
  
  RESULTS
  There were 876 non-fatal myocardial infarctions and 346 deaths from coronary heart disease. Compared with current users, people who had recently stopped taking aspirin had a significantly increased risk of non-fatal myocardial infarction or death from coronary heart disease combined (rate ratio 1.43, 95% confidence interval 1.12 to 1.84) and non-fatal myocardial infarction alone (1.63, 1.23 to 2.14). There was no significant association between recently stopping low dose aspirin and the risk of death from coronary heart disease (1.07, 0.67 to 1.69). For every 1000 patients, over a period of one year there were about four more cases of non-fatal myocardial infarction among patients who discontinued treatment with low dose aspirin (recent discontinuers) compared with patients who continued treatment.
  
  
  CONCLUSIONS
  Individuals with a history of cardiovascular events who stop taking low dose aspirin are at increased risk of non-fatal myocardial infarction compared with those who continue treatment.
authors.affiliation: Spanish Centre for Pharmacoepidemiologic Research, Madrid, Spain. lagarcia@ceife.es
authors.forename: Luis A García
authors.initials: LA
authors.lastname: Rodríguez
authors.forename: Lucía
authors.initials: L
authors.lastname: Cea-Soriano
authors.forename: Elisa
authors.initials: E
authors.lastname: Martín-Merino
authors.forename: Saga
authors.initials: S
authors.lastname: Johansson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000008:administration & dosage*; D016022:Case-Control Studies; D003327:Coronary Disease / Q000209:etiology / Q000401:mortality; D006801:Humans; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology* / Q000401:mortality / Q000517:prevention & control; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D011379:Prognosis; D018570:Risk Assessment; D012307:Risk Factors; D055502:Secondary Prevention; D016903:Drug Monitoring
chemical_list: D010975:Platelet Aggregation Inhibitors; D001241:Aspirin