Occup Environ Med Aims: To examine exposure to workplace bullying as a risk factor for cardiovascular disease and depression in employees. Methods: Logistic regression models were related to prospective data from two surveys in a cohort of 5432 hospital employees (601 men and 4831 women), aged 18-63 years. Outcomes were new reports of doctor diagnosed cardiovascular disease and depression during the two year follow up among those who were free from these diseases at baseline. Results: The prevalence of bullying was 5% in the first survey and 6% in the second survey. Two per cent reported bullying experiences in both surveys, an indication of prolonged bullying. After adjustment for sex, age, and income, the odds ratio of incident cardiovascular disease for victims of prolonged bullying compared to non-bullied employees was 2.3 (95% CI 1.2 to 4.6). A further adjustment for overweight at baseline attenuated the odds ratio to 1.6 (95% CI 0.8 to 3.5). The association between prolonged bullying and incident depression was significant, even after these adjustments (odds ratio 4.2, 95% CI 2.0 to 8.6). Conclusions: A strong association between workplace bullying and subsequent depression suggests that bullying is an aetiological factor for mental health problems. The victims of bullying also seem to be at greater risk of cardiovascular disease, but this risk may partly be attributable to overweight. N o generally accepted definition of workplace bullying exists, but most definitions refer to aspects such as the persistence of bullying and the negative or detrimental effects perceived by the victim. 1 Examples of bullying include situations in which someone is subjected to social isolation or exclusion, the subject's work and work efforts are devalued, and the subject is threatened or otherwise worn down or frustrated. Thus, victimisation to workplace bullying may represent a social stressor related to a serious deficiency in perceived organisational justice and fairness. 2 7-9 However, the question whether workplace bullying predicts the onset of illness, such as cardiovascular disease and depression, has awaited longitudinal testing. Stress can contribute to the development of disease. Chronic overactivity or underactivity in cardiovascular and metabolic systems in relation to prolonged stress has been found to be an aetiological factor for cardiovascular disease and hypertension. 13 When representing a major chronic stressor, workplace bullying can be hypothesised to increase the victims' vulnerability to these stress related diseases. Testing this hypothesis requires repeated measurements of victimisation for the establishment of continuous bullying, a measurement strategy that has not been applied in prior occupational studies. We carried out a prospective study to examine whether exposure to workplace bullying is associated with new reports of cardiovascular disease and depression among hospital personnel. The study data on prolonged exposure to bullying were based on two surveys over two years. METHODS Study population A postal questionnaire was sent to all 10 969 employees (1712 men and 9257 women) aged 18-63 years, working in Finnish hospitals in 1998. Ten per cent of the employees were doctors, 47% nurses, 12% laboratory and x ray department staff, 12% administrative staff, and 19% maintenance, cleaners, and other workers. Respondents who were still working in the hospitals two years later, were sent a follow up questionnaire in 2000. The surveys gathered information on bullying, stress related diseases, and behavioural risks on both occasions. The approval of the Ethics Committee of the Finnish Institute of Occupational Health was obtained for the study. Measures Bullying was measured by the following question: ''Workplace bullying refers to a situation where someone is subjected to social isolation or exclusion, his or her work and efforts are devalued, he or she is threatened, derogatory comments are made about him or her in his or her absence, or other negative behaviour that is aimed to torment, wear down, or frustrate the victim occur. Have you been subjected to such bullying? ''. 5 Cardiovascular disease and depression were measured using a self administered checklist of common chronic diseases. 14 For each disease, the respondent was requested to indicate whether or not a medical doctor had diagnosed him or her as having the disease. Cardiovascular disease was identified if the respondent reported myocardial infarction, angina pectoris, cerebrovascular disease, or hypertension. Depression was identified if the respondent reported that a medical doctor had diagnosed him or her as having depression. Incident cases of cardiovascular disease and Other variables were: smoking (smoker versus nonsmoker, and the number of cigarettes smoked per day); alcohol consumption in grams of absolute alcohol per average week (cut offs for high consumption 280 and 190 g for men and women, respectively); weight and height for the calculation of body mass index (overweight indicated by BMI .29 kg/m 2 ); and demographics (sex, age, occupation, income, and job contract (permanent versus temporary) obtained from the employers' records). Statistical analysis We used logistic regression analysis to test predictive relations of bullying to cardiovascular disease and depression. The first step tested reversed causality. Baseline diseases and other baseline characteristics were set as predictors for incident caseness of bullying (bullied in the second survey) among employees who did not report being bullied at baseline. The second step examined whether prolonged bullying predicted incidence of cardiovascular disease and depression. Three exposure groups were formed: employees not reporting bullying in the first survey and in the second survey (the control group); employees who reported victimisation either in the first survey or the second survey (but not both); and victims of prolonged bullying (reporting victimisation in both surveys). Those with baseline diseases were excluded. Odds ratios and 95% confidence intervals (CI) for new cardiovascular disease and depression in the second survey were adjusted for sex, five year age categories, and income tertiles (calculated separately for men and women). The third step reported logistic models where the associations of bullying with cardiovascular disease and depression were additionally adjusted for those behavioural risk factors that showed significant differences between the levels of bullying. Finally, interactions between these behavioural risks and bullying on cardiovascular disease and depression were studied. All analyses were conducted using the SPSS 9.0 software package. RESULTS Response rates and sample attrition A total of 8104 employees (74%) responded to the first survey. The mean age of the respondents was 43.3 years, 88% were women, 77% had a permanent job contract, and the mean income was 1849 per month. The corresponding figures for the eligible population were 42.9 years, 84%, 75%, and 1884 per month, respectively. Thus, any differences between the respondents and all eligible employees were small. Of respondents to the first survey, 6674 were working in the target hospitals two years later at the time of the second survey. Of the 6674 eligible respondents of the first survey, 5432 (81%) responded to the second survey. Female, high income, non-depressive, and permanent employees were slightly overrepresented Reversed causality The prevalence of reported bullying was 5.2% in the first survey and 5.9% in the second survey. Bullying as a predictor of new disease Of the respondents, 1.7% reported bullying experiences in both surveys. As table 3 shows, prolonged bullying was associated with the onset of cardiovascular disease and depression. After adjustment for sex, age, and income, the odds ratio of incident cardiovascular disease for prolonged bullying, compared with no bullying, was 2.3. The corresponding odds ratio of new physician diagnosed depression was 4.8. For those who reported bullying only in one of the two surveys, the odds ratio of depression was 2.3. The role of behavioural risk factors Of the behavioural risk factors, overweight predicted the onset of new cardiovascular disease (OR 2.95, 95% CI 2.20 to 3.95). Smoking and high alcohol consumption at baseline were associated with an increased risk of depression (ORs 1.54 (95% CI 1.08 to 2.21) and 1.53 (95% CI 1.00 to 2.34), respectively). Examination of whether bullying contributes to behavioural risk factors shows that prolonged bullying, compared with no bullying, did not predict subsequent smoking (baseline adjusted OR 0.64, 95% CI 0.19 to 2.19), heavy alcohol consumption (OR 1.06, 95% CI 0.46 to 2.46), or overweight (OR 0.64, 95% CI 0.25 to 1.64). However, individuals who were bullied at both times were more often overweight at baseline than non-victims (OR 2.04, 95% CI 1.20 to 3.46). Adjustment for overweight in addition to demographic factors attenuated the association between bullying and new cardiovascular disease (OR 1.62, 95% CI 0.75 to 3.50 for bullying at both times versus at neither time), but did not affect the association between bullying and depression (OR 4.16, 95% CI 2.01 to 8.63). Interactions between bullying and overweight were not significant for cardiovascular disease (p = 0.902) and depression (p = 0.174). Main messages N There is a strong association between workplace bullying and subsequent depression. Exposure to bullying predicts the onset of depression in a doseresponse gradient. N There is also an association between bullying and incidence of cardiovascular disease. However, this association may partly be attributable to obesity. Policy implications N Evidence of depression implies that the problem of workplace bullying should be effectively treated in workplaces. N Early identification and prevention of workplace bullying may be a key factor in attempts to minimise its adverse effects on mental health
