Analysis of determinants of work-related accidents in the construction industry

Purpose Our knowledge about the relative weight and interactions between determinants of work-related accidents is still limited. This prospective study aims to evaluate the role of organizational factors versus contract relationship in multiple injury risk. Methods A cohort of 4998 injured workers in the period 2000 to 2001 was defined from the Navarra Occupational Health Institute Register (with a population-based coverage of 15,600 construction workers). Cox proportional hazards survival regression was performed with endpoint (multiple injuries) defined as suffering a third disabling injury during 2 years of follow-up. Predictor variables were obtained from official accident reports and by linkage with population occupational databases. Results Nonqualified workers have an increased risk of multiple injury (hazard ratio = 1.61; 95% CI = 1.14–2.28) as observed for qualified structural jobs, such as bricklayers (hazard ratio = 1.81; 95% CI = 1.30–2.52). Training period workers had almost threefold accident risk (hazard ratio = 2.72; 95% CI = 1.39–5.31). Risk increases linearly with firm size, and shows a quadratic relationship with worker age. Temporary contracts did not increase the risk of multiple injuries (hazard ratio = 1.24; 95% CI = 0.93–1.66). Power analysis of our Cox regression model reached 80% for detecting a 40% increase in risk ratio. Conclusion Organizational factors, particularly working conditions and experience, contribute to accident risk to a greater extent than the contract relationship, suggesting the development of preventive strategies.