Trends in mortality from major causes and lifestyle factors by per capita prefectural income: Ecological panel data analysis from 1995 to 2016 in Japan

In Japan, trends in mortality and lifestyle have not been fully investigated according to subnational socioeconomic factors. Forty-seven prefectures (subnational units) were divided into quartiles by annual per capita prefectural income. Age-standardized mortality from all causes, cancer, heart disease, and stroke was averaged by quartile in 1995, 2000, 2005, 2010, and 2015. Data from the National Health and Nutrition Survey were obtained for periods 1 (1995–1997), 2 (1999–2001), 3 (2003–2005), 4 (2007–2009), 5 (2012), and 6 (2016). Body mass index (BMI), the intake of vegetables and salt, the number of steps, and the prevalence of current smoking and drinking for the 40–69-year age range were standardized by 10-year age groups in the 2010 Japanese population and were averaged by quartile. Differences in mortality and lifestyle by year and period, and quartile were tested using a two-way analysis of variance. Mortality decreased in both sexes and mortality in men from all causes, cancer, and stroke differed by quartile, with mortality highest in the first (lowest) quartile. BMI in men and smoking prevalence in women increased, whereas remaining lifestyle factors except for the prevalence of drinking decreased in women. BMI and the number of steps in both sexes and current smoking prevalence in women differed by quartile, with lower quartiles showing a higher BMI and fewer step counts. In conclusion, favorable trends and significant differences in mortality from all causes, cancer, and stroke in men and BMI in women were observed by per capita prefectural income level.