Objective : To examine whether drug treatment for hypertension prevents the first occurrence of cerebral hemorrhage, a population-based case-control study was conducted in Hirara-city, Okinawa Prefecture, Japan.
Methods : Cases were 36 hypertensive persons, 45 to 84 years of age, who had experienced cerebral hemorrhage from 1991 to 1994. Twenty of them were ascertained to be hypertensive by residential mass health examinations before the occurrence of cerebral hemorrhage, and other cases were ascertained by stroke register. Controls were 158 hypertensive persons unaffected by stroke and other life-threatening diseases, who were matched with their corresponding case for sex, age and mean blood pressure. All controls were ascertained as hypertensive by health examinations in 1991. Data on antihypertensive treatment, during the two years before the occurrence for cases and between April 1992 and March 1994 for controls, were collected by claims for medical care cost and medical records. Conditional logistic regression was employed for matched analyses.
Results : Regarding treatment, 16 (44.4%) cases and 36 (23.5%) controls did not receive antihypertensive drug treatment, and 13 (36.1%) cases and 30 (19.6%) controls had interrupted treatment. Compared with continuously treated persons, untreated persons and interrupted persons had odds ratios of 6.27 (95% confidence interval : 2.21 to 17.8) and 4.94 (1.79 to 13.6) for cerebral hemorrhage, respectively. Cases were prescribed antihypertensive drugs for fewer months than controls. By subgroup analyses limited to the cases ascertained as hypertensive by mass health examinations and their matched controls, the same relation was observed.
Conclusion : Among hypertensive persons, non-treatment and interruption of antihypertensive drug treatment were associated with a higher risk of cerebral hemorrhage. Long-term continuous treatment with antihypertensive drug (s) prevents the first occurrence of cerebral hemorrhage.