Analysis of differences in stroke mortality rates between metropolitan and non-metropolitan areas in Japan from 1999 to 2023

Purpose

This research examined trends in stroke mortality rates between metropolitan and non-metropolitan areas in Japan.

Methods

Data regarding stroke mortality for individuals aged 40–79 from 1999 to 2023 were sourced from Japan’s Vital Statistics. Age-standardized stroke mortality rate was computed annually for by sex and area. Moreover, an age-period-cohort analysis was performed, and the estimated stroke mortality rate was calculated for each age group, year, and cohort by sex and area.

Results

Throughout the years, the age-standardized mortality rate in non-metropolitan areas consistently exceeded that of metropolitan areas, while the difference in the age-standardized mortality rate diminished over years in men. Furthermore, the difference in estimated mortality rates between these two areas diminished and ultimately vanished from the cohorts born in the 1920s to those born in the late 1930s for men and from cohorts born in the 1920s to those born in the early 1950s for women. Conversely, starting from the cohorts born in the 1950s, the regional difference in the estimated mortality rates began to expand in men.

Conclusions

The results revealed the difference in age-standardized stroke mortality rates between the areas, and the difference in mortality rate varied depending on the birth cohort.