Changes in stroke mortality rates for 1950 to 1997: a great slowdown of decline trend in Japan.

BACKGROUND AND PURPOSE Stroke is the second leading cause of death in Japan. We sought to examine changes in stroke mortality rates by age, sex, and birth cohorts from 1950 to 1997. METHODS The numbers of deaths from stroke and the population by age and sex in subjects aged 55 to 79 years between 1950 and 1997 were obtained from national vital statistics. Poisson regression analyses for annual percentage changes were used to explore these trends. RESULTS Stroke mortality rates decreased since the mid-1960s for both men and women. Four periods of the decline are identified. In the first period (1950 to 1964), the age-adjusted annual percent changes averaged 0.9% for men (P<0.05) and -0.6% for women (P>0.05). In the second period (1965 to 1974), the annual change averaged -5.0% for men and -5.2% for women (both P<0.01). In the third period (1975 to 1989), the annual change averaged -8.6% for men and -8.7% for women (both P<0.01). In the fourth period (1990 to 1997), the annual change averaged -1.2% for men (P>0.05) and -3.0% for women (P<0.01). In the fourth period, the slowdown of the decline in stroke mortality was most evident in the older age groups of men. CONCLUSIONS The findings suggested that along with an increasing aging population, the slowdown in the decline of stroke mortality rates, especially for men, is of considerable concern. Efforts to control stroke should be vigorously continued in the 2000s.