Medical information is increasingly processed electronically. This study will describe the similarities and differences in the data recorded by different databases of electronic healthcare database. These will include the General Practice Research Database (GPRD) and the Myocardial Ischaemia National Audit Project (MINAP) and hospital episode statistics (HES).

This study is part of the CALIBER (Cardiovascular disease research using linked bespoke studies and electronic records) programme funded over 5 years from the NIHR and Wellcome Trust. The central theme of the CALIBER research is linkage of the Myocardial Ischaemia National Audit Project (MINAP) with primary care (GPRD) and other resources. The overarching aim of CALIBER is to better understand the aetiology and prognosis of specific coronary phenotypes across a range of causal domains, particularly where electronic records provide a contribution beyond traditional studies. CALIBER has received both Ethics approval (ref 09/H0810/16) and ECC approval (ref ECC 2-06(b)/2009 CALIBER dataset).

Specific aims are as follows:

1. To validate the linkage between the three databases (General Practice Research Database (GPRD), Myocardial Ischaemia National Audit Project (MINAP), Hospital Episode Statistics (HES)) (checking age, sex and unique identifiers across databases) and establish a cohort of patients with acceptable registration status for further analysis.

2. To describe the ways that MIs are recorded between the three datasets based on the 'best case definition' in each database.

   1. Starting from a 'best case definition' MINAP MI definition (based on the CALIBER phenotype algorithm, which itself is based on the international definition of MI), to examine the way in which the MINAP MI is recorded in GPRD and HES. This analysis will examine STEMI and NSTEMI separately.
   2. Starting from a 'best case definition' algorithm for MI in GPRD (to be decided by GPRD/LSHTM/UCL), to examine the ways in which this MI is recorded in MINAP and HES.
   3. Starting from a 'best case definition' choice of ICD-10 codes for MI in HES, to examine the ways in which this MI is recorded in MINAP and GPRD.

3. To examine predictors of non-concordance between the three datasets.

4. To develop recommendations for a new gold standard definition of MI in each of the databases, based on aims 1-3.

A detailed protocol for this study is available on request. This study has been approved by the Independent Scientific Advisory Committee (ISAC) and by the MINAP Academic Group (MAG).

Study investigators:

R. Boggon, GPRD; Dr S. Denaxas, UCL; Professor H. Hemingway, UCL; E. Herrett, LSHTM; Dr A. Shah, UCL; Professor A. Timmis; Professor T. van Staa, GPRD.

Inclusion Criteria:

• Aged 18+
• Patients in GPRD practices which are deemed "up to standard" by GPRD criteria
• Patients in GPRD whose practice agreed to be linked to the MINAP and HES datasets.
• Patients whose records are deemed "acceptable" by GPRD criteria
• Patients whose age and sex, as recorded in GPRD is the same as that recorded in HES and MINAP.
• Patients with evidence of myocardial infarction in one of the datasets (HES, MINAP, GPRD, ONS) between 1st January 2003 and 6th August 2009.

Exclusion Criteria:

-

The study population is comprised of "acceptable" patients registered at those GPRD practices that agreed to the linkage with MINAP and HES, whose practices are "up to standard" according to GPRD criteria. Practices taking part in the GPRD are chosen to be representative of UK practices, and 98% of people in the UK are registered with a GP. Therefore the GPRD should be a representative sample of the UK population.