Premature menopause is associated with increased risk of cerebral infarction in Japanese women

Objective: Few epidemiological studies have examined the relationship between age at menopause and stroke incidence, and none have done so in Japanese women. Here, we investigated the relationship between age at menopause and stroke incidence in a large group of Japanese women. Methods: The study participants were 4,790 postmenopausal women aged 36 to 89 years enrolled in the Jichi Medical School Cohort Study, a population-based prospective study. Baseline data were obtained by questionnaire and health checkups between April 1992 and July 1995 in 12 rural areas in Japan. The incidence of all strokes and stroke subtypes was monitored. Results: Mean (SD) participant age was 61.0 (6.7) years, and mean (SD) age at menopause was 48.3 (4.8) years. A total of 185 strokes were observed during a mean follow-up of 10.8 years. On adjustment for age, systolic blood pressure, total cholesterol, body mass index, smoking habits, and alcohol drinking habits, hazard ratios (95% CIs) of stroke for women who underwent menopause before age 40 years, at 40 to 44 years, at 45 to 49 years, and at 55 years or after relative to those who underwent menopause at age 50 to 54 years were 1.56 (0.78-3.12), 1.59 (1.00-2.51), 1.28 (0.92-1.78), and 0.83 (0.38-1.81), respectively. However, hazard ratios (95% CI) of cerebral infarction for women who underwent menopause before age 40 years, at 40 to 44 years, at 45 to 49 years, and at 55 years or after relative to those who underwent menopause at age 50 to 54 years were 2.57 (1.20-5.49), 1.49 (0.80-2.78), 1.06 (0.67-1.68), and 1.08 (0.43-2.74), respectively. Conclusions: Our data suggest that Japanese women who undergo menopause before age 40 years are at an increased risk of cerebral infarction. Premature menopause should be considered an indicator of the need for more aggressive medical intervention aimed at the prevention of cerebral infarction.