Canadian provincial trends in antihypertensive drug prescriptions between 1996 and 2006

Background: Little is known regarding potential differences in antihypertensive prescribing practices at a Canadian provincial level. Our objective was to determine provincial differences in the use of antihypertensive drug therapy in Canada.

Methods: Using longitudinal drug data (IMS CompuScript database; IMS Health Canada), we examined the increase in number of prescriptions dispensed for all antihypertensive agents for each province over an 11-year period (1996-2006).

Results: Over the 11-year study period, antihypertensive prescriptions increased by 106.2% for single-drug therapy (from 35.8% in Prince Edward Island and Newfoundland to 167.2% in British Columbia) and by 112.8% (from 22.0% in New Brunswick to 216.0% in Québec) for combination-drug therapy. Among drug classifications, angiotensin receptor blockers had the largest increase for single-drug therapy and angiotensin-converting enzyme inhibitors-diuretics for combination-drug therapy. There were marked provincial differences in the increase in total antihypertensive therapy, ranging from British Columbia, with an increase of 262%, to Prince Edward Island and Newfoundland, where the increase was 134%.

Conclusion: Large increases in antihypertensive prescriptions occurred in all provinces of Canada, but the provinces varied substantially in the increase in total and drug-specific classes of antihypertensive drugs. The basis for provincial differences in antihypertensive prescriptions remains unknown and is likely multifactorial but may relate in part to initial provincial variations in diagnosis, treatment, and control of hypertension, as well as individual provincial drug policies.