Long-term adherence to antihypertensive therapy: a survey in four primary care clinics

BACKGROUND: Many hypertensive patients have suboptimal control of their blood pressure. One of the most common causes is poor adherence with treatment. AIM: To identify factors associated with poorer adherence to antihypertensive treatment. METHODS: The study was conducted in four urban clinics of Clalit Health Services (Israel's largest Health management organization): 3799 patients aged > 20 years with hypertension in whom a new antihypertensive medicine was started in a 3-year period were included. Data included: age; gender; chronic diseases; type of antihypertensive medicine; and adherence with treatment. Reasons for non-adherence had been evaluated in a random sample of 453 of the medical records. RESULTS: Of the patients, 2234/3799 (58.8%) stopped >or= 1 medicine. Lower adherence was associated with female gender, new immigration, ischemic heart disease and being a non-diabetic. Adherence was related to the type of medicine. The highest rates of adherence were found with the use of angiotensin receptor blockers (59.1%) and selective beta-blockers (59%), and the lowest with non-selective beta-blockers (30.1%). There was no documentation of the reason to medicine cessation in 183/453 (40.4%) of the medical records. In 20.1% of cessations, the physician continued to prescribe the drug, despite the fact that the patient had stopped purchasing it. Common reasons for treatment cessation were side effects (15%) and lack of blood pressure control (5.5%). CONCLUSIONS: Adherence with antihypertensive treatment declines with time and is associated with the type of medicine, and sociodemographic and clinical backgrounds. Family physicians must increase their documentation and awareness to medicine adherence.