Background Workplace bullying is a severe stressor that is related to numerous adverse outcomes, such as poor health and low quality of life. Previous studies have shown that bullying is a strong predictor of long-term sickness absence that can have substantial costs for both society and the individual. A commonly used definition of bullying is when an individual, over a prolonged period of time, such as six months, perceives him/herself as being exposed to negative acts from superiors or co-workers that it is difficult to defend one-self against. The causes of long-term sickness absence are multifactorial. One possible pathway linking workplace bullying and sickness absence is through chronically increased levels of perceived stress.

Objective To examine if perceived stress mediated the association between workplace bullying and subsequent long-term sickness absence.

Methods The PRISME cohort was established in 2007 and re-examined in 2009. Questionnaire data about workplace bullying (self-labelling question) and perceived stress (Cohen’s perceived stress scale) were obtained from 4114 individuals. Participants were followed in registers on long-term sickness absence (≥30 consecutive days of sickness absence).

Results We had 4,114 participants with no history of long-term sickness absence in the previous two years contributing 6,331 observations in 2007 and/or 2009, giving a total of 6331 observations of which 430 were among workplace bullied. Workplace bullying was associated with subsequent sickness absence (OR = 2.05; 95% CI: 1.57–2.65) and concurrent high perceived stress levels (OR = 2.34; 95% CI: 1.86–2.96). A high perceived stress level was also associated with subsequent sickness absence (OR = 1.33; 95% CI: 1.13–1.56). Perceived stress explained 13% (95% CI: 6–23%) of the total association between bullying and sickness absence.

Conclusions The association between workplace bullying and subsequent long-term sickness absence may be partially mediated by perceived stress.