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Discontinuation of low dose aspirin and risk of myocardial infarction: case-control study in UK primary care

BMJ 2011; 343 doi: (Published 19 July 2011) Cite this as: BMJ 2011;343:d4094
  1. Luis A García Rodríguez, director1,
  2. Lucía Cea-Soriano, epidemiologist1,
  3. Elisa Martín-Merino, epidemiologist1,
  4. Saga Johansson, senior principal scientist/associate professor23
  1. 1Spanish Centre for Pharmacoepidemiologic Research (CEIFE), Madrid 28004, Spain
  2. 2AstraZeneca Research and Development, Mölndal, Sweden
  3. 3Institute of Medicine, Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden
  1. Correspondence to: L A García Rodríguez lagarcia{at}
  • Accepted 13 May 2011


Objectives 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.

Design Nested case-control study.

Setting The Health Improvement Network (THIN) database in the United Kingdom.

Participants 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).

Main outcome measures 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.


  • We thank Nesta Hughes and Catherine Hill, of Oxford PharmaGenesis, who provided writing support funded by AstraZeneca.

  • Contributors: LAGR contributed to study design, data collection, statistical analysis, interpretation of data, and drafting the report; LC-S and EM-M contributed to data collection and statistical analysis and reviewed the report; SJ contributed to study design, interpretation of data, and reviewed the report. LAGR is guarantor.

  • Funding: This study was funded by an unrestricted research grant from AstraZeneca Research and Development Mölndal. The sponsors played no part in the design or conduct of the study.

  • Competing interests: All authors have completed the Unified Competing Interest form at (available on request from the corresponding author); LAGR, LC-S and EM-M work for CEIFE, which has received research funding from AstraZeneca; SJ is an employee of AstraZeneca.

  • Ethical approval: This study was approved by the multicentre research ethics committee (08/H0305/49).

  • Data sharing: No additional data available.

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