Secular Trends in Prescription Patterns of Single-Pill Combinations of an Angiotensin-Converting Enzyme Inhibitor or Angiotensin Receptor Blocker Plus a Thiazide Diuretic for Hypertensive Patients in Taiwan.

BACKGROUND Poor adherence to recommended drug regimens is one of the fundamental issues behind suboptimal control rates of hypertension worldwide. Single-pill combinations (SPCs) improve patient adherence, decrease cost, and are increasingly prescribed in the Western societies. We conducted this study to elucidate the prescription patterns and the secular trends of SPCs in Taiwan. METHODS We retrospectively reviewed the reimbursement database of Taiwan's National Health Insurance from 2002 to 2007. Among the one million-person random samples, information from those coded with ICD-9 401-405 and antihypertensive prescriptions was obtained. RESULTS From 2002 to 2007, there had been amore than 7.5-fold increase in annual prescription frequency of SPCs of an angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) plus a thiazide diuretic (from 1.1% to 8.5%, p < 0.001) among 302,628 hypertensive patients. Likewise, among patients treated with at least ACEIs or ARBs and diuretics, the relative proportion of SPC use, in contrast to free combinations, increased markedly (from 10.8% to 54.2%, p = 0.005). Incorporating patient antihypertensive treatment prior to SPCs prescription,we categorized the SPC prescription patterns into 3 groups: naïve, switch, and add-on. The increase in patients taking SPCs came mostly from the naïve SPC prescription group (from 2.3% in 2002 to 28.8% in 2007 among all patients treated with ACEIs or ARBs and thiazide diuretics, p = 0.003). Compared to both naïve and add-on SPC users, patients in the switch group had a greater pill burden and more comorbidities, whichmight drive physicians to switch from free combinations to SPCs. CONCLUSIONS Single-pill combinations are well-accepted and increasingly prescribed in Taiwan, particularly in drug-naïve hypertensive patients. This finding might indicate an aggressive attitude towards early hypertension control among physicians in Taiwan. KEY WORDS Angiotensin-converting enzyme inhibitor; Angiotensin receptor blocker; Diuretic; Hypertension; Single-pill combinations.