Duration of initial antihypertensive prescription and medication adherence: A cohort study among 203,259 newly diagnosed hypertensive patients

• Published in: International journal of cardiology 2015-03, Vol.182, p.503-508
• Main Authors: Wong, Martin C.S, Tam, Wilson W.S, Wang, Harry H.X, Cheung, Clement S.K, Tong, Ellen L.H, Cheung, N.T, Leeder, Stephen R, Griffiths, Sian M
• Format: Article
• Language: English
• Subjects: Age Factors; Antihypertensive Agents - therapeutic use; Cardiovascular; Chinese population; Cohort study; Duration; Female; Follow-Up Studies; Hong Kong - epidemiology; Humans; Hypertension - drug therapy; Hypertension - epidemiology; Initial antihypertensive prescription; Male; Medication Adherence; Middle Aged; Odds Ratio; Prescription Drugs; Treatment Outcome
• ISSN: 0167-5273; 1874-1754
• DOI: 10.1016/j.ijcard.2014.12.058

Abstract Background Optimal adherence with antihypertensive medications is crucial to prevent hypertension-related complications. This study evaluated whether the duration of initial antihypertensive prescription is associated with better medication adherence in a large sample of Chinese hypertensive patients. Methods and results From a validated clinical database which consists of all patients in the public healthcare sector in Hong Kong, all patients on their first-ever antihypertensive agent from 2001 to 2005 (N = 203,259) were included and followed-up for 12 months (and up to 5 years in separate analyses). The average age was 58.7 years (SD 17.3), and the overall rate of optimal adherence (as measured by having the Proportion of Days Covered ≥ 0.80) was 32.4%. The proportion of patients whose initial prescriptions lasted for ≤ 6 days; 7–14 days; 15–28 days and ≥ 29 days was 23.7%, 24.3%, 15.1% and 37.0%, respectively. The corresponding proportion of optimal adherence was 18.1%, 20.1%, 31.0% and 50.3%. The binary logistic regression analysis showed that after controlling for age, sex, socioeconomic status, service type, drug class, and district of residence, those whose initial prescription was 7–14 days (adjusted odds ratio [AOR] = 1.17, 95% C.I. 1.12–1.22); 15–28 days (AOR = 1.90, 95% C.I. 1.82–1.99) and ≥ 29 days (AOR = 4.13, 95% C.I. 3.96–4.31) were significantly more likely to be adherent than those who were prescribed for ≤ 6 days (all p < 0.001). These findings remained significant in separate analyses where the period of follow-up was extended to 5 years. Conclusions Shorter duration of first antihypertensive prescriptions was associated with poorer medication adherence, and this practice should be avoided if possible.