Discontinuation of angiotensin-converting enzyme inhibitors: a cohort study

Angiotensin-converting enzyme inhibitors (ACEI) are among the most commonly used antihypertensive agents worldwide. Factors associated with their discontinuation in clinical practice are not well defined as studies undertaken in different ethnic populations have yielded conflicting result. We aimed to identify predictors of ACEI discontinuation among Chinese patients.

We used a validated clinical database for this cohort study. We included all adult patients aged ≥ 18 years who visited any primary care clinic in one Territory of Hong Kong and who were prescribed an ACEI from January 2004 to June 2007. The cumulative incidence of discontinuation 180 days after prescription of an ACEI was measured. Factors associated with discontinuation were evaluated by multiple regression analyses.

Among 9398 eligible patients, 14·0% discontinued their prescriptions. After controlling for patient's age, gender, socio-economic status, service type, district of residence, visit type and number of comorbidities, patients aged 70 or above [adjusted odds ratio (AOR) = 1·27, 95% CI 1·04-1·56, P = 0·022], male subjects (AOR = 1·21, 95% CI 1·05-1·40, P = 0·008), new visitors (AOR = 0·64, 95% CI 0·55-0·75, P < 0·001), patients who obtained their prescriptions in Family Medicine Specialist Clinic (FMSC) (AOR = 1·43, 95% CI 1·14-1·79, P = 0·002), patients who lived in the less urbanized district (AOR = 1·96, 95% CI 1·55-2·48, P < 0·001) and the most rural district (AOR = 1·24, 95% CI 1·03-1·49, P = 0·027), and patients with no comorbidity, were more likely to discontinue their medications.

Physicians should pay attention to adherence problems particularly when prescribing ACEI to male patients, those who are older than 70 years, have no comorbidity, live in less urbanized or more rural areas, qualify for fee-waiver, are new attendees of consultations or obtain their ACEI prescriptions in FMSC. Future research should evaluate the reasons for ACEI discontinuation among these higher-risk groups.