Job strain and sick leave among Japanese employees: a longitudinal study

The present study is an investigation of the association between job stress, determined on the basis of a demand-control model or worksite social support at the baseline, and absence due to illness among employed Japanese males and females.

We analyzed 448 male and 81 female subjects who had taken no sick leave in the year preceding the baseline (1997) and observed them all until 1999. A self-administered questionnaire was the source information collected. It consisted of questions on socio-demographic variables, occupations, health-related behavior, a Japanese version of the Job Content Questionnaire, and the number of absences in the year preceding both the baseline and follow-up. Logistic regression analyses were used to determine how the characteristics of a job at the baseline affected sickness absence of 5 days or longer per year; controls were established for the gender, age, level of education completed, occupation, number of cigarettes smoked daily, and the amount of alcohol consumed weekly.

Compared to the lowest tertile of the ratio of demand to control (job strain), the highest tertile was significantly associated with an increased risk of sickness absence of 5 days or longer per year (odds ratio 3.02; 95%CI 1.00-9.16) at follow-up. The dose-response relationship was supported (p for trend <0.05). However, individual variables of job demand, job control, and worksite social support were not significantly associated with the risk of absence from illness.

The study provided prospective evidence that job strain leads to an increased risk of sick leave among Japanese employees.