Series of Studies for Outcomes Research and Pharmacoeconomic Evaluation
Date Issued
2009
Date
2009
Author(s)
Liu, Pang-Hsiang
Abstract
BACKGROUNDlthough antihypertensive pharmacotherapy is widely considered to reduce the premature mortalities and comorbidities associated with hypertension, no consensus has yet been reached as to the appropriate choice of first-line medication. Knowledge of existing prescription patterns in the treatment of newly-diagnosed hypertension can provide useful information for improving clinical practice in this field. The aims of this dissertation are to determine the prescription patterns and time trends for antihypertensive medication in newly-diagnosed cases of uncomplicated hypertension in Taiwan and to compare these with current clinical guidelines. Furthermore, we conducted an outcome research to assess the risk of stroke associated with various antihypertensive drugs among previously uncomplicated hypertensive patients. ETHODSirst, a total of 6,536 newly-diagnosed patients with uncomplicated hypertension, aged over 30 years, were identified from the representative 200,000-person sample in the computerized reimbursement database of the National Health Insurance in Taiwan. These patients were followed from 1998 to 2004 with all diagnoses, prescription data and medication charges being retrieved for subsequent analysis. For the outcome research of antihypertensive treatment, another retrospective cohort study was undertaken, covering the period from 1997 to 2004, on a 1,000,000-person random sample obtained from Taiwan''s National Health Insurance reimbursement database. Between January 1999 and December 2004, 29,759 patients aged 30 years or older were identified as newly-diagnosed uncomplicated hypertensive cases. They were followed up until the end of 2004. A time-dependent Cox’s proportional hazards model was specified to analyze the risk of stroke development.ESULTSrescription patterns varied by age, gender and clinical facilities, with mono-therapies being found to be dominant in the first year, albeit declining over time. Calcium channel blockers and beta-blockers were the most frequently prescribed antihypertensive drugs, either alone or in combinations. Although least expensive, the prescription rates of diuretics were low, at 8.3% for mono-therapies and 19.9% overall. The prescription rate for angiotensin receptor blockers was elevated considerably over time. After controlling for other related factors by multiple logistic regression analysis, angiotensin receptor blockers were found to be prescribed mainly by medical centers or regional hospitals. Among the 29,759 uncomplicated hypertensive patients in the 1,000,000-person random sample of NHI reimbursement database, 1,078 new cases of stroke were identified and followed up for at least one month during the study period, including 654 ischemic stroke cases. After adjustment for various risk factors, the hazard ratio of developing stroke was significantly higher for poor medication compliance (hazard ratio 1.5-1.9), old age, male, and comorbid diabetes mellitus and/or other heart diseases. Different categories of antihypertensive medications were not associated with differential effects on stroke development. In the subsequent analysis, we found that patients receiving pharmacotherapy with beta-blockers were 1.3 (95% confidence interval 1.0-1.6) times more likely to develop ischemic stroke than those who had been treated with other types of antihypertensive medication.ONCLUSIONShe above findings indicate the existence of a gap between current clinical practice and the desired goal of cost-effectiveness in antihypertensive treatment in our country, which should be corrected. Poor medication compliance is a key determinant of developing stroke among hypertensive patients. Our research suggests that there has been no differential effect of antihypertensive medication on overall risk of stroke, whereas beta-blockers might be associated with more ischemic stroke. Further studies are needed to corroborate this hypothesis.
Subjects
antihypertensive therapy
beta-blocker
compliance
cost-effectiveness
National Health Insurance
pharmacoepidemiology
SDGs
Type
thesis
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