Advantages and limitations of antihypertensive treatment for stroke risk in a general population: the Akita Stroke Registry.
BACKGROUND
Although the association between stroke risk and blood pressure (BP) levels related to antihypertensive medication has been an object of study for a long time, there is little agreement as to the relationship in a general population study.


RESULTS
We obtained mass health screening data regarding 156,847 (142,989 untreated and 13,858 treated) subjects from the Akita Prefectural Federation of Agricultural Cooperative for Health and Welfare from 1991 to 1998. Stroke events were determined from the Akita stroke registry between 1991 and 2001. 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 JNC-6), with or without antihypertensive medication. Stroke developed in 1,323 (0.8%) individuals in the study population within 3 years after the health examination. Among untreated groups, the relative hazard linearly increased with elevation of the BP grade. In the untreated group, stroke risk was significantly higher (relative hazard 2.1, 95% confidence interval (CI) 1.6-2.7) in the subjects with high-normal BP levels than with optimal BP levels. In the treated group, stroke risk was significantly higher in patients with high-normal BP levels (relative hazard 2.0, 95% CI 1.0-4.2) than with optimal BP levels. Furthermore, stroke risk was significantly higher in the treated groups with normal BP levels (relative hazard 3.1, 95% CI 2.0-4.9) compared with the untreated group with optimal BP levels.


CONCLUSIONS
Although antihypertensive medication can reduce stroke risk, treated patients within non-hypertension levels may still have a higher risk compared with untreated subjects of the same categories.
Department of Cardiology, Jichi Medical University, Shimotsuke City, Tochigi, Japan. izumi@jichi.ac.jp
Manabu
M
Izumi
Kazuo
K
Suzuki
Tetsuya
T
Sakamoto
Masato
M
Hayashi
D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology*; D007564:Japan; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology* / Q000503:physiopathology*
D000959:Antihypertensive Agents