title: Association between low-dose acetylsalicylic acid reinitiation and the risk of myocardial infarction or coronary heart disease death.
abstract: In secondary cardiovascular prevention, discontinuation of acetylsalicylic acid (ASA) is associated with an increased risk of cardiovascular events. This study assessed the impact of ASA reinitiation on the risk of myocardial infarction and coronary heart disease death.
  
  
  
  Patients prescribed ASA for secondary cardiovascular prevention and who had had a period of ASA discontinuation of ≥90 days in 2000-2007 were identified from The Health Improvement Network (N = 10,453). Incidence of myocardial infarction/coronary heart disease death was calculated. Survival analyses using adjusted Cox proportional hazard models were performed to calculate hazard ratios and 95% confidence intervals for the risk of myocardial infarction/coronary heart disease death associated with ASA use patterns after the initial period of discontinuation. Individuals who were prescribed ASA during follow-up were considered reinitiators.
  
  
  
  The incidence of myocardial infarction/coronary heart disease death was 8.90 cases per 1000 person-years. Risk of myocardial infarction/coronary heart disease death was similar for current ASA users, who had been continuously exposed since reinitiation, and patients who had not reinitiated ASA (hazard ratio 1.27, 95% confidence interval 0.93-1.73). Among reinitiators, an additional period of ASA discontinuation was associated with increased risk of myocardial infarction/coronary heart disease death compared with no reinitiation (current users: hazard ratio 1.46, 95% confidence interval 1.13-1.90; noncurrent users: hazard ratio 1.70, 95% confidence interval 1.31-2.21).
  
  
  
  ASA reinitiation was not associated with a decreased risk of myocardial infarction/coronary heart disease death. This may be explained by confounding by indication/comorbidity, whereby higher-risk patients are more likely to reinitiate therapy. An additional period of ASA discontinuation among reinitiators was associated with an increased risk of myocardial infarction/coronary heart disease death.
authors.affiliation: Spanish Centre for Pharmacoepidemiologic Research (CEIFE), Madrid, Spain Andalusian Bioinformatics Research Centre (CAEBi), Seville, Spain.
authors.forename: María E
authors.initials: ME
authors.lastname: Sáez
authors.affiliation: Spanish Centre for Pharmacoepidemiologic Research (CEIFE), Madrid, Spain Andalusian Bioinformatics Research Centre (CAEBi), Seville, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: González-Pérez
authors.affiliation: AstraZeneca Gothenburg, Mölndal, Sweden.
authors.forename: Saga
authors.initials: S
authors.lastname: Johansson
authors.affiliation: AstraZeneca Gothenburg, Mölndal, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Himmelmann
authors.affiliation: Spanish Centre for Pharmacoepidemiologic Research (CEIFE), Madrid, Spain lagarcia@ceife.es.
authors.forename: Luis A
authors.initials: LA
authors.lastname: García Rodríguez
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000008:administration & dosage*; D002423:Cause of Death / Q000639:trends; D003324:Coronary Artery Disease / Q000453:epidemiology* / Q000517:prevention & control; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000517:prevention & control; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D055502:Secondary Prevention / Q000379:methods*; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology; D028761:Withholding Treatment
chemical_list: D010975:Platelet Aggregation Inhibitors; D001241:Aspirin
keywords: Acetylsalicylic acid; coronary heart disease death; discontinuation; myocardial infarction; reinitiation