Influence of Municipal- and Individual-level Socioeconomic Conditions on Mortality in Japan

Background The health effect of area socioeconomic conditions has been evident especially in Western countries; however, limited research has focused on the effect of municipal-level socioeconomic conditions, especially in Asia. Purpose Multilevel research using data from the Japan Collaborative Cohort Study, a large cohort study followed from 1990 to 2006, was conducted to examine individual as well as municipal socioeconomic conditions on risk of death, adjusting for each other. Method We included 24,460 men and 32,649 women aged 40 to 65 years at baseline in 35 municipalities as our study population. Primary predictors were municipal socioeconomic conditions (proportion of college graduates, per capita income, unemployment rate, and proportion of households receiving public assistance) and individual socioeconomic conditions (education level and occupation). Results Among men, the multilevel logistic estimate (standard errors) of proportion of college graduates and unemployment rate for mortality from cardiovascular disease were −0.399 (0.094) and −0.343 (0.122), respectively. Among women, the multilevel logistic estimate (standard errors) of proportion of college graduates and per capita annual income for mortality from injuries were −0.386 (0.171) and −1.069 (0.407). Individual education level and occupation were associated with all-cause mortality, in particular, mortality from cardiovascular disease or injuries. Interactions between individual education level and indicators of municipal socioeconomic conditions were observed for mortality from cancer and cardiovascular disease among men and mortality from injuries among women. Conclusion Municipal and individual socioeconomic conditions were independently and interactively associated with premature death; this suggests that reducing social inequalities in health demands a focus on municipal conditions in addition to those of individuals.