Little is known about health of the growing subpopulation of the working poor in Japan. We aimed to evaluate health status and healthcare utilization in relation to income among Japanese working adults. We conducted a one-month prospective cohort study using a health diary in working adults from a nationally representative random sample in Japan. Based on the government criterion, the working poor group was defined as earning an equivalent annual income of less than 1.48 million Japanese-yen. For health status, we measured symptomatic episodes and health-related quality of life (HRQOL). For healthcare utilization, we measured frequencies of visits to a physician or pharmacy, and use of complementary and alternative medicine (CAM). We constructed multiple linear regression models for these measures adjusted for age, gender, and co-morbidity, using annual equivalent income as a 4-level categorical variable.
Of 3,568 participants originally enrolled in the study panel, 3,477 completed the survey (response rate 97%). For the purpose of the study, of the 3,568 participants, we analyzed 1,406 working adults who were 20–65 years old (mean age, 40.8 yr: 58.4% men). There were 106 (7.5%) working poor: 56 men (6.8% of working men) and 50 women (8.5% of working women). Compared to the highest income group, the working poor reported the greater number of symptomatic episodes and a slightly lower score of physical component of HRQOL (PCS8). The numbers of symptomatic episodes among the working poor and the highest income group during the 1-month study period were 9.79 (SD, 8.77) and 7.01 (SD, 7.34), respectively (p < 0.01). The PCS8 among the working poor was 48.71 (SD, 7.05) and it was 50.34 (SD, 6.55) among the highest income group (p < 0.01). There was no difference of healthcare utilization by the different levels of income.
We concluded that the working poor (7.5% of all working adults) more frequently report symptomatic episodes and show slightly poorer physical health status, compared to the highest income group. Healthcare utilization is not affected by income.