To evaluate the association between stroke risk and blood pressure (BP) levels with regard to the usage of antihypertensive medications.
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.
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.
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.
aComprehensive Research and Education Center for Planning of Drug Development and Clinical Evaluation, Tohoku University 21st Century COE Program, Japan
bDepartment of Planning for Drug Development and Clinical Evaluation, Tohoku University Graduate School of Pharmaceutical Sciences, Sendai, Japan
cDepartment of Biostatistics/Epidemiology and Preventive Health Sciences, School of Health Sciences and Nursing, University of Tokyo, Tokyo, Japan
dDepartment of Epidemiology, Research Institute for Brain and Blood Vessels-Akita, Akita, Japan
eDepartment of Medical Genetics, Tohoku University Graduate School of Medicine, Sendai, Japan
fDepartment of Health Science, Shiga University of Medical Science, Shiga, Japan
gDepartment of Biostatistics, School of Public Health, University of Tokyo, Tokyo, Japan
hDepartment of Clinical Pharmacology and Therapeutics, Tohoku University Graduate School of Pharmaceutical Sciences and Medicine, Sendai, Japan
Received 2 May, 2008
Revised 6 August, 2008
Accepted 16 September, 2008
Correspondence to Professor Yutaka Imai, MD, PhD, Department of Clinical Pharmacology and Therapeutics, Tohoku University Graduate School of Pharmaceutical Sciences and Medicine, 1-1 Seiryo-cho, Aoba-ku, Sendai 980-8574, Japan Tel: +81 22 717 7770; fax: +81 22 717 7776; e-mail: firstname.lastname@example.org
Part of the work was presented at the 21st Scientific Meeting of the International Society of Hypertension (ISH 2006), Fukuoka, Japan.