| Summary: | 博士 === 臺北醫學大學 === 藥學研究所 === 95 === Background and Purpose
Antihypertensive medications have represented a tremendous financial burden to the health care plan globally. This study examined the utilization pattern of the antihypertensive agents to analyze the underlying reasons responsible for the pharmaceutical expenditure in Taiwan during 1997 to 2002 as well as to evaluate the long term impact of a new pharmacological class antihypertensive medicine- angiotensin II antagonist (AIIA) to the clinical utilization of the existing antihypertensive medications in Taiwan.
Methods
The claims data during 1997 to 2002 were obtained from National Health Insurance Academic Research Database (NHIARD), which include ambulatory service record and prescription data of the entire population. Drug expenditure was decomposed into 5 components: relative drug price, number of patients treated, average physician visit per patient, Defined Daily Dose (DDD) per physician visit and a residual. Gross growth of DDD and prescription numbers, market share analysis including monetary market share (MMS), clinical market share (CMS), prescription market share (PrMS) and patient market share (PtMS), market penetration time and DDDs/ prescription were used to assess AIIA''s impact on the angiotensin converting enzyme inhibitors (ACEI), β- Blockers (BB), calcium channel blockers (CCB) and other miscellaneous antihypertensive agents (MIS).
Result
Total antihypertensive drug spending increased 102% during this period, mainly due to the compounding effect from the increment of patients treated (34%) and DDD per physician visit (33%). Residual analysis revealed that the aggregate residual for antihypertensive agents only had a 7% effect; the brand- name product had 11% increment and the generic product had a 12% decrement. It also showed that while hospital sector had a positive 11% residual, primary care clinics had an 11% decrement. Detailed analysis on each sub- group revealed that CCB had the most significant gross growth of DDDs and prescription at 117.1 and 3.4 million increments, respectively. CMS results revealed that the introduction of AIIA had the most significant impact to the clinical utilization of MIS (-5.5%) and a moderate impact to both BB (-4.5%) and ACEI (-4.1%). Whereas PMS demonstrated the most significant impact to MIS (-6.5%), a moderate impact to ACEI (-2.3%) and a very minor impact to BB (-0.9%). AIIA, however, had a positive CMS (+3.9%) and PMS (+2.4%) correlation with CCB. AIIA utilization implicated by relative growth strength for the CMS and PMS at Medical Center, Regional Hospital, District Hospital and Primary Care Clinic were 4.95 : 3.77 : 2.77 : 1 and 5.28 : 4.17 : 2.94 : 1, respectively.
Conclusion
The most important factors that contribute to the expenditure surge of antihypertensive agents are number of treated patients and DDD per physician visit. While physicians at the hospital sector adopted more new and innovative medications, their counterpart at the primary care clinics tended to switch some off- patent products to the generics. The introduction of AIIA did not affect the negative clinical utilization drift of MIS and BB since this depressing trend started before AIIA introduction. On the other hand, the preference of using CCB and AIIA to control hypertension among the physicians in Taiwan was on the ascending side. Medial center was the early leading adaptor for AIIA and furthermore played an important role in the utilization diffusion of AIIA.
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