Abstract
AIMS: Exposure to workplace bullying is associated with an increased risk of mental health conditions, yet it is debated whether the association is causal. This study aims to address this by examining whether onset of workplace bullying is associated with initiating treatment with psychotropic medication, here used as a proxy measure for onset of common mental disorders. METHODS: We used two longitudinal datasets from Sweden and Denmark (mean age: 47.4, women: 52.8%), combined with national registry data on psychotropic medication purchases. Using a target trial approach, the study population (N = 25 309) consisted of employees free of workplace bullying and psychotropic medication use at baseline. We used Cox proportional hazards regression (adjusted for sociodemographic variables, depressive symptoms and psychosocial work characteristics) to assess the association between onset of exposure to workplace bullying and incident treatment with psychotropic medication during 2 years. RESULTS: In total, 1490 individuals (5.9%) experienced onset of workplace bullying. Bullying onset was associated with incident treatment with any psychotropic medication (HR: 1.42, 95% CI 1.15-1.77, model adjusted for sociodemographic variables). This association was attenuated in the fully adjusted model (HR: 1.24, 95% CI 0.99-1.53). In analyses focusing on antidepressant treatment, the estimates were stronger (HR: 1.55, 95% CI: 1.15-2.09, fully adjusted model). The results further demonstrated an exposure-response relationship, such that higher frequency of bullying exposure was associated with an increased risk of initiating any psychotropic treatment and antidepressants. CONCLUSIONS: Individuals experiencing onset of workplace bullying were at higher risk of starting antidepressant treatment within 2 years. This is the first study showing that onset of workplace bullying can contribute to the development of mental health conditions requiring medical treatment. These results underline the importance of preventive interventions that reduce workplace bullying.