Mortality risks in relation to occupational category and position among the Japanese working population: the Jichi Medical School (JMS) cohort study

OBJECTIVES A well-known demographic finding in modern society is the inverse association between socioeconomic status and mortality. The purpose of the study was to examine socioeconomic indicators, such as occupational category (white-collar vs blue -collar) and occupational position (managerial vs non-managerial) as determinants of all -cause, cardiovascular disease (CVD) and cancer mortality in a Japanese working population. DESIGN This is a prospective study. PARTICIPANTS Data of a baseline survey were collected between 1992 and 1995, and ultimately 6929 Japanese workers aged 65 years and younger (3333 men and 3596 women) from 12 rural communities across Japan were followed until the end of 2005. MAIN OUTCOME MEASURES The HRs of death and 95% CIs from all causes were calculated using the Cox proportional hazard model. RESULTS Men in blue-collar jobs showed an increased all-cause mortality risk compared with those in white-collar jobs (HR 1.64, 95% CI 1.10 to 2.45). Stratified by occupational category, non-managerial women in blue-collar jobs showed a decreased CVD mortality risk compared with managerial women (HR 0.15, 95% CI 0.03 to 0.81), after adjusting for confounding factors. However, non-managerial women in white-collar jobs showed an increased mortality risk compared with managerial women, although this was not significant (HR 2.34, 95% CI 0.25 to 21.87). CONCLUSIONS Socioeconomic disparity according to occupational category was related to the risk of all-cause mortality among Japanese men. There is a potential interaction of occupational category and position in CVD mortality among Japanese women.