By linking three separate sets of data, this research showed that it is common for people to stop taking a recommended anti-clotting drug once they are discharged from hospital after a heart attack. There is also evidence that stopping taking the drug is associated with an increased rate of death, although this research did not prove a causal link between the two.

Why was this work needed?

Clopidogrel is an anti-clotting drug which is recommended for people who have recently had a heart attack. However, it is difficult to know whether people continue to take this for the recommended length of time after they are discharged from hospital and, if they choose to stop taking it, what happens to them.

What happened?

This research linked together three sets of data to try to understand more about what happens to people once they are discharged from hospital, after receiving treatment for a heart attack. It linked records of someone’s treatment and prescriptions in hospital with GP data showing what happened to them after discharge. They then linked these to national data recording individual deaths.

What were the benefits?

The research demonstrated that stopping taking clopidogrel is common, and that this is associated with an increased number of heart attacks and death. However, while the research demonstrated an association, it could not prove a causal link. Future research will continue to investigate this.

What type of data was involved?

This research linked data from four sources: Clinical Practice Research Datalink (CPRD), Hospital Episode Statistics (HES) Admitted Patient Care, Office for National Statistics (ONS) mortality and Myocardial Ischaemia National Audit Project (MINAP).

The Health and Social Care Information Centre (now NHS Digital) carried out the linkage. After this, the records were de-personalised before being used by the researchers.

Who funded and collaborated on this work?

This study was funded by AstraZeneca UK Ltd. Researchers from CPRD, representatives from the MINAP data custodians, and cardiovascular healthcare professionals collaborated on this research.

Where can I go for more information?

Clopidogrel discontinuation after acute coronary syndromes: frequency, predictors and associations with death and myocardial infarction--a hospital registry-primary care linked cohort (MINAP-GPRD)