Household income and the risk of incident hypertension in employees at multiple workplaces in Japan: J-HOPE.

This cohort study aimed to investigate the association between household income and incident hypertension in a Japanese employed population. During 2012, a total of 4314 normotensive daytime employees (3153 men and 1161 women) were included in this study. Participants had a wide range of occupations and were employed at one of 12 workplaces from various economic sectors in Japan. After a 2-year follow-up, incident hypertension was compared among groups according to household income: <5.0, 5.0-7.9, 8.0-9.9, and ≥10.0 million Japanese yen (¥)/year. A Cox proportional hazard model was used to calculate the hazard ratio for incident hypertension in each household income group, compared with the group earning <5.0 million ¥/year. The hazard ratios for men were 1.52 (95% confidence interval, 1.08-2.18) for 5.0-7.9 million ¥/year, 1.49 (0.98-2.27) for 8.0-9.9 million ¥/year, and 1.92 (1.23-3.01) for ≥10.0 million ¥/year after adjusting for age, baseline systolic blood pressure, worksite, type of occupation, number of family members, and smoking status. This positive relationship was attenuated but remained significant after further adjustment for alcohol consumption and body mass index, both of which were higher among men with higher household income. Conversely, there was no significant difference for women in the risk of incident hypertension among household income groups, although those with higher household income tended to have a lower risk of incident hypertension. Household income is positively associated with the onset of hypertension in Japanese employed men working daytime hours.