Prospective Cohort Study of Work Functioning Impairment and Subsequent Absenteeism Among Japanese Workers

OBJECTIVE: This study examined the association of work functioning impairment as measured by work functioning impairment scale (WFun) and subsequent sick leave. METHODS: A prospective cohort study was conducted at a manufacturer in Japan, and 1263 employees participated. Information on sick leave was gathered during an 18-month follow-up period. RESULTS: The hazard ratios (HRs) of long-term sick leave were substantially increased for those with a WFun score greater than 25 (HR = 3.99, P = 0.003). The incidence rate ratios (IRRs) of days of short-term absence gradually increased as scores of WFun increased (IRR = 1.18, P < 0.001 in the subjects with WFun of over 25 comparing with those with WFun of 14 or less). CONCLUSIONS: Assessing work functioning impairment is a useful way of classifying risk for future sick leave among employees.