Age-, sex-, and diagnosis-specific incidence rate of medically certified long-term sick leave among private sector employees: The Japan Epidemiology Collaboration on Occupational Health (J-ECOH) study

BACKGROUND: Long-term sick-leave is a major public health problem, but data on its incidence in Japan are scarce. We aimed to present reference data for long-term sick-leave among private sector employees in Japan. METHODS: The study population comprised employees of 12 companies that participated in the Japan Epidemiology Collaboration on Occupational Health Study. Details on medically certified sick-leave lasting ≥30 days were collected from each company. Age- and sex-specific incidence rate of sick-leave was calculated for the period of April 2012 to March 2014. RESULTS: A total of 1422 spells in men and 289 in women occurred during 162,989 and 30,645 person-years of observation, respectively. The three leading causes of sick-leave (percentage of total spells) were mental disorders (52%), neoplasms (12%), and injury (8%) for men; and mental disorders (35%), neoplasms (20%), and pregnancy-related disease (14%) for women. Incidence rate of sick-leave due to mental disorders was relatively high among men in their 20s–40s but tended to decrease with age among women. Incidence rate of sick-leave due to neoplasms started to increase after age 50 in men and after age 40 in women, making neoplasms the leading cause of sick-leave after age 50 for women and after age 60 for men and the second leading cause after age 40 for women and after age 50 for men. Pregnancy-related disease was the second leading cause of sick-leave among women aged 20–39 years. CONCLUSIONS: These results suggest that mental disorder, neoplasms, and pregnancy-related disease are the major causes of long-term sick-leave among private sector employees in Japan.