Roles of age, length of service and job in work-related injury: a prospective study of 446 120 person-years in railway workers

Objectives Because work-related injuries are common and yet the mechanisms through which various types of injuries relate to age, length of service and job remain unknown, this study assessed the role of age, length of service and job in work-related injury. Methods Prospective study of all 164 814 permanently employed male workers at the French national railway company during 1998-2000, based on the company's injury database: 446 120 person-years, 15 195 injuries with working days lost, coded using the company's injury classification, which is derived from that of the French health insurance scheme. We investigated the incidence of 10 types of injury: fall on same level, fall to lower level, handling materials/machine parts during assembly, handling objects, lifting/handling equipment, collision with/by moving objects, collision with/by vehicles, operating machines/equipment, using hand tools and other injuries. Data were analysed using negative binomial regression. Results Workers aged <25 years were subject to a higher injury risk from handling materials/machine parts during assembly, and collision with/by moving objects or vehicles. Older workers, especially those aged 50-55 years, were subject to a higher risk of fall and injury resulting from lifting/handling materials/equipment/objects or from collision with/by moving objects/vehicles. Using hand tools was a risky task for workers aged <30 or >= 40 years. The relative risk decreased steadily with increasing length of service with the company, from 2.6 for 1 year to 1.0 for >= 30 years, and the slope of the trend is stronger for fall to lower level, lifting/handling materials/equipment and collision with/by moving objects. Conclusion Younger and older ages and shorter length of service are at risk for various types of injuries. Preventive measures should improve working conditions, especially for younger/older ages, provide knowledge through specific training during the first years in a job and help workers to be more aware of risks associated with their age, years of employment and job.