Evaluating the Effectiveness of an Occupational Health and Safety Management System Certification Program on Firm Work Injury Rates in Alberta, Canada.

Background: Occupational health and safety management systems (OHSMS) certification programs have the potential to improve workplace health and safety. In Canada, the Certificate of Recognition (COR) program is an example of such program and has been introduced in many industries and provinces. This study's objective was to identify whether the implementation of the COR program led to greater reduction in firm work-related injuries in Alberta, Canada.

Methods: Using firm- and claim-level data from the Workers' Compensation Board of Alberta and COR registration data from Government of Alberta, the effect of becoming COR-certified on firm-level injury rates was assessed using a matched difference-in-differences study design with population-averaged negative binomial regression models.

Results: A total of 14,377 certified firms were matched with 11,338 non-certified firms during the years 2000 to 2015. Firms that became certified had a greater reduction in the lost-time injury rate (IRR: 0.86, 95% CI 0.83-0.88) and disabling injury rate (IRR 0.97, 95% CI 0.94-1.00) relative to the change in injury rates among similar non-certified firms. The effectiveness of OHSMS certification was strongest in the transportation, manufacturing and trade sectors, in more recent years, and among firms certified using the standard COR program as opposed to the program adapted for small employers.

Conclusions: The findings suggest that COR can be an effective program, but that the effectiveness of this program is dependent on the context in which it is implemented, such as the industry sector, time period, and type of audit program.