Objective: To evaluate whether physicians are prescribing antihypertensive drugs appropriately and according to the recommendations of the Canadian Hypertension Society.
Design: Retrospective cohort study.
Setting: Family medicine teaching clinic in Montreal.
Participants: A cohort of 183 patients followed between 1993 and 1995. Of 350 patients registered at the clinic, 167 were excluded because diagnosis of hypertension was not supported by chart review, their charts contained insufficient information, they were pregnant or younger than 18 years, or they had secondary hypertension and complex medical conditions.
Main outcome measures: The dependent variable was the antihypertensive medication. Independent variables were age and sex of patients, duration of hypertension, total number of visits and number of visits for hypertension, number of physicians consulted at the clinic, associated medical conditions, diagnosis of target organ damage, blood pressure readings, and associated medications.
Results: Diuretics were prescribed most frequently (45.9%). Angiotensin-converting enzyme (ACE) inhibitors ranked second (28.4%), followed by calcium channel blockers (26.2%) and beta-blockers (18.0%). Age, sex, duration of hypertension, and blood pressure readings were not associated with medications. Prescription of beta-blockers was strongly associated with previous myocardial infarction, but not with diagnosis of angina pectoris. Patients with contraindications to beta-blockers were less likely to receive them and more likely to receive calcium channel blockers. Only 32% of diabetic patients received ACE inhibitors.
Conclusion: Results suggest that some prescriptions for antihypertensive medications are inappropriate, but that physicians are following some of the Canadian Hypertension Society's recommendations. A better understanding of physicians' prescribing behaviours could help target continuing education interventions to improve prescribing for hypertension.