Antihypertensive drug therapy in Saskatchewan: patterns of use and determinants in hypertension.
BACKGROUND
The benefits of continuous treatment of hypertension have been extensively documented in randomized controlled trials. However, clinical trials may not reflect actual drug use in the population.


OBJECTIVE
To examine the distribution and determinants of patterns of use of antihypertensive agents in the first 5 years of hypertension treatment in Saskatchewan.


METHODS
Patterns of use and modifications to therapy were derived from a careful examination of medication use in a cohort of 19 501 subjects aged 40 to 79 years, without recognized cardiac disease and initiating therapy with an angiotensin-converting enzyme inhibitor, a calcium antagonist, or a beta-blocker in Saskatchewan between 1990 and 1993.


RESULTS
Angiotensin-converting enzyme inhibitors (37.4%), followed by calcium antagonists (27.5%) and beta-blockers (26.4%), were the most commonly prescribed agents to initiate treatment in our study population. Patients with diabetes were less likely to be dispensed a beta-blocker, as were younger and female patients. Previous visits to a cardiologist decreased the likelihood of receiving combination therapy or angiotensin-converting enzyme inhibitors but increased that of using calcium antagonists. Apart from dose adjustment, 89% of study subjects underwent at least 1 modification to their initial regimen, at a median time of 134 days. After 1 year, only 33.8% of patients were still using their initial drug. An early decrease in the proportion of patients continuing to receive initial therapy was noted, especially among beta-blocker users.


CONCLUSIONS
Erratic drug-taking behaviors were observed in this Saskatchewan population. In addition, initial drug use does not seem to be in accordance with the stepped-care approach to hypertension therapy recommended in the Canadian guidelines.
Bourgault
C
C
Department of Epidemiology and Biostastics, Royal Victoria Hospital, McGill University Health Centre (MUHC), 687 Pine Ave W, Ross 4.29, Montreal, Quebec, Canada H3A 1A1.
Rainville
B
B
Suissa
S
S
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000627:therapeutic use*; D011307:Drug Prescriptions / Q000706:statistics & numerical data; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D012525:Saskatchewan / Q000453:epidemiology
D000319:Adrenergic beta-Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers