Time trends in the prevalence of depressive disorder symptoms in the Danish workforce, 2012 to 2018

BACKGROUND: Over the last decade, and well-before the COVID-19 pandemic, the prevalence of mental health problems has increased in many European countries, particularly in youth, raising public health concerns. Yet, there has been little focus on the mental health status of the working population, and it is unknown if the proportion of workers with impaired mental health is growing as well. In this paper, we report change in the prevalence of depressive disorder in a large nationwide sample of the Danish workforce (N = 76,802) from 2012 to 2018. METHODS: We used data from the Work Environment and Health in Denmark study, a bi-annual nationwide survey on working conditions and health. We measured depressive symptoms using the Major Depression Inventory and defined prevalence of depressive disorder by a score ≥21, in accordance with previous clinical validation studies. Using a log-binomial regression model, we estimated change in prevalence of depressive disorders from 2012 to 2018 with 95% confidence intervals (95% CI). RESULTS: From 2012 to 2018, the prevalence of depressive disorder increased from 7.0% (95% CI: 6.7-7.4) to 9.4% (9.0-9.9) corresponding to an adjusted increase of 36.1% (27.4-45.4) over the 6-year period. We observed a statistically significant increase in the prevalence in every wave, from 2012 to 2014 (adjusted change in prevalence: 10.8%, 3.2-18.9), from 2014 to 2016 (8.6%, 1.3-16.4)), and from 2016 to 2018 (13.1%, 6.0-20.7)). The increase occurred in both sexes, all age groups and for all types of occupational status, but was more pronounced among women, younger workers and workers of low occupational status. CONCLUSIONS: In a large nationwide sample of the Danish workforce, we observed an increasing prevalence of depressive disorder from 2012 to 2018. The results indicate that the general trend towards increased levels of mental health problems also encompasses the workforce and underlines the need for public health action. KEY MESSAGES: • The prevalence of depressive disorder in the Danish workforce increased considerably from 2012 to 2018. • The increase in prevalence of depressive disorder was observed in all groups, but was particularly pronounced for women, younger workers and basic-skilled workers.