Methods

Ischemic heart disease (IHD) is a leading cause of morbid-ity and mortality that is often managed in primary care;1 however, recent evidence indicates a wide variability in the management of such patients.2,3 The increasing use of elec-tronic medical records (EMRs) could facilitate improved monitoring of patients with IHD. However, unlike the case of diabetes, where structured fields in the EMR (such as laboratory results and treatments) can be used to accurately identify patients,5 using the EMR to develop a registry of IHD patients is difficult.6 Therefore, in jurisdictions where providers are not incentivised to systematically code diag-noses, approaches to help identify patients with IHD are needed to facilitate quality improvement efforts. With this goal in mind, we developed and tested a novel EMR search algorithm focusing on the unstructured text in the medical history fields. We also examined whether searching for nitrate prescriptions in the EMR would increase the accu-racy of identification of patients with IHD as has been pro-posed in similar studies.