Socioeconomic status and self-reported health among middle-aged Japanese men: results from a nationwide longitudinal study

Objective: To examine potential associations between socioeconomic factors and self-rated health among a national sample of Japanese men aged 50-59 years between 2005 and 2010, including the 2008 global financial crisis. Design: Prospective cohort study. Setting: Randomly selected 2515 census areas from a total of 1.8 million census areas in Japan. Participants: This study utilised data from a national, longitudinal survey conducted by the Ministry of Health, Labour and Welfare. Starting in 2005, 16 738 Japanese men aged 50-59 years were recruited and sent a questionnaire each year. We analysed data for the 6-year period (2005-2010) from participants who had worked for over 20 years in the same industry (n=9727). Main outcome measures: We focused on worsening self-rated health status by occupation, education and employment contract. Results: Working in the manufacturing industry was associated with worsening self-rated health scores when compared to those working in management (HR=1.19; 95% CI 1.04 to 1.37). A relationship between education level and worsening self-rated health was also identified as follows: junior high school (HR=1.49; 95% CI 1.31 to 1.69), high school (HR=1.29; 95% CI 1.17 to 1.42), and vocational college (HR=1.25; 95% CI 1.07 to 1.46), when compared with those holding university-level qualifications. Precarious employment (HR=1.17; 95% CI 1.00 to 1.37) was also associated with worsening self-rated health status in the current study. Conclusions: This study suggests that working in manufacturing for more than 20 years and having lower education levels may have a significant impact on the self-rated health of middle-aged Japanese men. This may reflect a progressive decline in Japanese working conditions following the global financial crisis and/or the impact of lower socioeconomic status.