Purpose: Patients' self-reported drug exposure is subjected to memory errors and different sources of bias. Utilization of prescription records is impaired with non-compliance and over-the-counter (OTC) drug utilization. This study compared patients' self-report (PS) to physician's prescriptions of cardiovascular drugs (CVDs).
Methods: The PGRx database is constituted by networks of specialized centers that recruited cases of 15 different diseases including myocardial infarction (MI) cases, and a network of general practitioners recruiting a pool of potential referents. For MI cases and referents, data on all drug utilization within the 2 years preceding the index date were obtained from PS and from physician's report of their prescriptions (PP). Patients' reports were obtained using a structured telephone interview complemented with an interview guide containing names of diseases and pictures of drug packages. Comparisons were made on exposure to each class of CVDs, for different time-windows, 2 months, 3-12 months and 13-24 months prior to the index date.
Results: The concordance between physician and patient report was assessed on 2702 patient-physician pairs. Agreement was excellent overall (kappa = 0.83, 95% confidence interval (CI): 0.81-0.85). Prevalences of exposure were very close between PS and PP for all classes of prescription CVDs.
Conclusion: Using a standardized and systematic collection of information on drug exposure directly from patients appeared to provide similar information to using physician prescription records over a 2-year recall period.