Stroke risk and antihypertensive drug treatment in the general population: the Japan arteriosclerosis longitudinal study.

OBJECTIVE: To evaluate the association between stroke risk and blood pressure (BP) levels with regard to the usage of antihypertensive medications. METHODS: From the Japan arteriosclerosis longitudinal study, 11,371 participants from the four population-based cohort studies (aged 40-89) were followed up for a mean of 9.5 years. A Poisson regression model, adjusting for possible confounding factors, was used to investigate the risk of first stroke among six BP-based categories (BP defined according to recent guidelines), in relation to the use of antihypertensive medications. RESULTS: There were 324 incident cases of first stroke. Among untreated groups, the relative hazard increased linearly with the elevation of BP grade (trend P = 0.0001). The untreated group with normal BP had a significantly higher stroke risk [relative hazard 2.09, 95% confidence interval 1.09-4.01] than the untreated group with optimal BP. There was no stepwise increase in stroke risk observed among treated groups (trend P = 0.1). The stroke risk among treated groups, even among those with optimal BP (relative hazard 4.10, 95% confidence interval 1.17-14.4), was significantly higher than that in the untreated groups with the same BP level. CONCLUSION: Treated individuals with optimal BP had a higher stroke risk than untreated ones with optimal BP. Healthcare providers need to be vigilant for residual cardiovascular risks in treated hypertensive patients.