Antihypertensive agents have been found to decrease morbidity and/or mortality associated with cardiovascular disease (CVD). Surveys have shown that hypertension has been diagnosed in many patients but remains uncontrolled. One factor may be the lack of persistence to treatment.
To evaluate persistence with antihypertensives and its determinants among newly treated patients.
A cohort of 21,011 patients with essential hypertension was reconstructed from prescription records in the Régie de l'assurance maladie du Québec administrative database. We included subjects between 50 and 64 years of age newly treated for hypertension with diuretics, beta-blockers, angiotensin-converting enzyme inhibitors, calcium-channel blockers, or angiotensin II receptor blockers prescribed individually or in combination. Cohort entry was from January 1, 1998, to December 31, 2000. Subjects were considered newly treated if they had not taken any antihypertensive agents in the year prior to the index date, which was defined as the date of the first prescription. Patients were followed until June 30, 2001; death; end of coverage; or occurrence of CVD. Main outcome measure was the persistence rate. The cumulative persistence rate was determined by Kaplan-Meier analysis. The rate ratio of discontinuing antihypertensive therapy was estimated using the Cox regression model.
The mean age of patients was 58 years. Persistence with antihypertensive therapy fell to 75% in the first 6 months after treatment and continued to decline over the next 3 years to 55%. During a one-year period of follow-up, with diuretics used as the reference class and controlling for several variables, patients prescribed other antihypertensive classes or combined therapy (HR 0.71; 95% CI 0.67 to 0.75) were found to have a better rate of persistence. Having diabetes (HR 0.86; 95% CI 0.79 to 0.94) and dyslipidemia (HR 0.71; 95% CI 0.66 to 0.76) increased the rate of persistence. Similar values were observed during the 3-year period of follow-up.
Barriers to persistence occur early in the course of therapy, and adherence continues to decline over a period of 3 years. Patients were least persistent to diuretic therapy.