Abstract
PurposeAdverse effects of antihypertensive therapy incur substantial cost. We evaluated whether any major classes of antihypertensive drugs were significantly associated with switching as a proxy measure of medication side effects in a large Chinese population in Hong Kong.MethodsFrom a clinical database, all adult patients newly prescribed an antihypertensive mono-therapy in Hong Kong between the years 2001–2003 and 2005 were included. Those who paid only one visit, died or stayed in the cohort for <180 days after the prescription, or prescribed more than one antihypertensive agent were excluded. The factors associated with switching at 180 days were evaluated by multivariate regression analyses. Age, gender, payment status, service type, district of residence, drug class, systolic and diastolic blood pressure levels were predictor variables.ResultsFrom 250,851 subjects, 159,813 patients were eligible. A total of 6,163 (3.9%) switched their medications within 180 days. Patients prescribed thiazide diuretics had the highest switching rate (5.6%), followed by ACEIs (4.5%), CCBs (4.4%) and beta-blockers (3.2%). When compared with ACEIs, patients on thiazide diuretics were significantly more likely to be switchers (adjusted odds ratio [AOR] 1.49, 95% C.I. 1.31–1.69, p<0.001), whilst patients prescribed CCBs and beta-blockers were similarly likely to have switching. Following these patients up for 5 years showed that thiazide had the most marked increase in switching rate.ConclusionsThe higher rates of switching among thiazide diuretics in this study might raise a probably greater incidence of their adverse effects in this Chinese population, yet other factors might also influence switching rates. Patients prescribed thiazide diuretics for longer term should be observed for their intolerability.
Highlights
Hypertension is the biggest contributor to global mortality and is rising in prevalence [1,2]
We have previously reported the rates of switching among antihypertensive agents in Chinese adults
The objective of this study was to evaluate the longer-term switching rates according to drug classes among all Hong Kong residents, and it tested the a priori hypothesis that there existed differences in switching rates among the major antihypertensive drug classes as reported in our previous study [22]
Summary
Hypertension is the biggest contributor to global mortality and is rising in prevalence [1,2]. Despite clinical consequences of uncontrolled hypertension as expressed in morbidity and mortality from cardiovascular disease and stroke being well recognized [2,9,10], very small proportions of patients achieve control at less than 140/90 mmHg [11] This problem is worse in countries belonging to the Asia Pacific region like China, where recent studies have found that only 3.5% of rural and 3.7% of urban hypertensive patients achieved optimal control [12,13]. It has been estimated by the American Heart Association that the yearly direct and indirect costs of hypertension exceeded 93.5 billion in 2011, and together with stroke and cardiovascular diseases, accounts for 17% of the total healthcare expenditure per year in the US [14]
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