Presumptive coverage policies and workers' compensation of post-traumatic stress disorder and other mental health conditions: a retrospective time-series study in Canada 2001-2019

Background: The impact of presumptive coverage policies for work-related mental health disorders has not been extensively studied to date. Using data from the Association of Workers' Compensation Boards of Canada (AWCBC), our objectives were to describe the evolution of compensated mental health conditions, and to explore the association between the implementation of presumptive coverage and the number of compensated mental health conditions. Methods: Datasets on mental health lost-time claims (LTCs) were obtained from the AWCBC for 2001-2019. The total number of all-cause LTCs was used as a denominator. Independent variables included presumptive coverage, union coverage, unemployment rate, proportion of service industry workers, proportion of working women, physicians and psychologists per 100,000 inhabitants, and workers' compensation board coverage. Regression and interrupted time series analyses were conducted. Results: Over the study period, mental health LTC accounted for 0.97% of all-cause LTCs: half of the former were PTSD cases. In the multivariate analysis, presumptive coverage policies restricted to PTSD were only positively associated with the proportion of PTSD LTCs (Incidence Rate Ratio, [IRR] = 1.237, 95% CI 1.005-1.521) but not with other mental health LTCs. More lenient policies were positively associated with the proportion of PTSD LTCs (IRR = 1.211, 95% CI [1.025-1.430]), and non-PTSD mental health LTC (IRR = 1.435; 95% CI [1.001-2.058]). Conclusions: Workers' compensation presumptive coverage policies for mental health conditions have the effect of increasing claim volumes for these conditions. When restricted to coverage of PTSD, the portion of PTSD of all LTC is larger, but there is no documented ripple effect on other mental health conditions.