By Michael H. Crawford, MD, Editor

SYNOPSIS: In a 12-year follow-up of surveyed Scandinavian employees, reported workplace violence and bullying increased the risk of future cardiovascular disease of a magnitude similar to other recognized cardiovascular disease risk factors.

SOURCES: Xu T, Magnusson Hanson LL, Lange T, et al. Workplace bullying and workplace violence as risk factors for cardiovascular disease: A multi-cohort study. Eur Heart J 2019;40:1124-1134.

Herrmann-Lingen C. Victimization in the workplace: A new target for cardiovascular prevention? Eur Heart J 2019;40:1135-1137.

Workplace stressors such as bullying and violence are associated with a higher risk of type 2 diabetes, but their role in cardiovascular (CV) disease is unclear. From three large Scandinavian longitudinal studies of working men and women, Xu et al studied four cohorts based on enrollment years ranging from 1995 to 2011. Employees aged 18-65 years with no prior CV disease and information available on workplace bullying and violence were identified. This resulted in a study population of more than 79,000 people.

Workplace bullying and exposure to or threat of violence were obtained from self-administered questionnaires. CV disease was defined as first hospitalization for coronary or cerebral vascular disease. Other biographical data were obtained to assess confounders and other stressors at work that could influence the results. The subjects’ mean age was 43 years; 53% of subjects were women.

The prevalence of bullying ranged from 8-13% over 12 months in the four cohorts. Mainly, the perpetrators were from within the company (79%), and 21% were clients. The prevalence of violence ranged from 7-17% over 12 months in the cohorts, and the perpetrators were mainly clients (91%). Only 10-14% of employees experienced both stressors at the same time. After a mean follow-up of 12.4 years, 3,229 CV events occurred in these employees. After adjustment for various covariates, bullying increased the risk of CV disease (hazard ratio [HR], 1.59; 95% confidence interval [CI], 1.28-1.40).

Workplace violence also increased CV disease risk (HR, 1.25; 95% CI, 1.12-1.40). The frequency of bullying increased the risk (frequent HR, 2.22; 95% CI, 1.23- 4.01). Frequent violence increased risk of cerebrovascular disease by 36%. The authors concluded that bullying and violence in the workplace are common and associated with a greater risk of developing CV disease.

COMMENTARY

Previous studies have revealed that mental illnesses such as depression are independent risk factors for CV disease, as are certain personality traits, such as hostility and anger. Also, social risk factors, such as low socio-economic status and stress, have been identified. Considering that workplace bullying and violence are related to some of the above risk factors, it is not surprising that they would be independent risk factors, too. In this study, the population-attributable risk was 5% for bullying and 3% for violence, which is similar to other well-established risk factors such as diabetes (4%). In addition, a dose response relationship was established for bullying, less so with violence. Sensitivity analyses with known confounders suggested these results were robust. Interestingly, there were no identified differences between the two sexes. Since such behavior potentially is modifiable, physicians and workplace managers need to be aware of these results.

There were limitations to this study. The authors relied on self-reporting on one day, and no further bullying or violence data were collected during follow-up. There is no information on underlying personality traits and behaviors, which could be important in understanding the results. It is possible that some victims may have exhibited negative behaviors that provoked inappropriate responses. Also, there may have been other stressors involved, such as marital conflict. The authors of these large studies did not provide data on clinical information such as blood pressure and cholesterol levels. Finally, this was a Scandinavian population, and the results may not be generalizable to other groups.

The main strengths of the study were the large population (> 79,000 people) and the long follow-up (mean = 12 years). Also, it is biologically feasible that these work stresses could lead to anxiety, depression, overeating, increased alcohol consumption, impaired sleep, and hypertension, all of which would explain an increased incidence of CV disease. The weaker association with violence compared to bullying may be due to the fact that almost all the violence was perpetrated by clients. The authors suggested that workers in these jobs may be self-selected for their ability to deal with irate clients better. In the final analysis, though, outcome studies that mitigate these behaviors need to be conducted to prove that eliminating bullying and violence would improve CV health.