Antihypertensive persistence and drug class

Noncompliance with antihypertensive therapy is a major problem that hinders successful hypertension management.

To study antihypertensive drug persistence for hypertensive patients in routine clinical settings.

Hypertensive patients were retrospectively studied (1994 through 1998) using databases managed by Saskatchewan Health. The study population (46,458 people) included all patients with an International Classification of Diseases-9 code of 401, 402, 403 or 404, or any four-digit code included in these categories, who received at least one antihypertensive therapy prescription during the first 4.5 years of the study and received no antihypertensive therapy 12 months before the dispensing of the first therapy. Prescriptions were placed into the following drug classes: angiotensin II antagonists, angiotensin-converting enzyme inhibitors, beta-blockers, calcium channel blockers and diuretics. Persistence was determined for four intervals in the patient's therapy at 180, 360, 540 and 720 days.

Drug class had a statistically significant (P<0.001) effect on persistence. Angiotensin II antagonists had the highest persistence followed by angiotensin-converting enzyme inhibitors, calcium channel blockers, beta-blockers and diuretics. Persistence decreased as the time interval increased. Females were significantly more persistent than males (P<0.005), and elderly patients were significantly more persistent than younger patients (P<0.001) at each of the four time intervals. For angiotensin II antagonists, age and sex did not affect persistence.

The consistently higher persistence associated with the use of angiotensin II antagonists may improve the management of hypertension.