Discontinuation of and changes in treatment after start of new courses of antihypertensive drugs: a study of a United Kingdom population

OBJECTIVE: To evaluate the incidence of discontinuation of and changes in treatment after newly prescribed courses of antihypertensive drugs of the four primary therapeutic classes: beta blocker, calcium channel blocker, and angiotensin converting enzyme inhibitor. DESIGN: A retrospective analysis of patients on an automated database of 1.2 million patients was conducted on visits between 1 October 1992 and 30 September 1993. SETTING: General practices in the United Kingdom. SUBJECTS: 37,643 patients with hypertension receiving a relevant drug in the time period were identified. A new course of treatment in at least one of the four therapeutic classes, defined as a drug not prescribed in the previous four months, was observed in 10,222 patients aged > or = 40 years. MAIN OUTCOME MEASURES: Patients changing to other treatment or discontinuing after initiating a new course of treatment, defined as the absence of a refill prescription for the new drug or another in its category within a six month observation period. RESULTS: Changes in or discontinuation of treatment were frequently observed, and by month six continuation rates ranged between 40% to 50% for all four classes of drugs. CONCLUSION: Low rates of continuation with a newly prescribed antihypertensive drug exist regardless of which drug is prescribed.