Objective: To determine the risk of stroke associated with various antihypertensive drugs among previously uncomplicated hypertensive patients.
Methods: A retrospective cohort study was undertaken, covering the period from 1997 to 2004, of 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.
Results: From the 29 759 uncomplicated hypertensive patients, 1078 new cases of stroke were identified and followed up for at least 1 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 sex, 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.
Conclusion: Poor medication compliance is a key determinant of developing stroke among hypertensive patients. This study 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.