title: Workplace bullying and subsequent health problems.
abstract: BACKGROUND
  Cross-sectional studies demonstrate that exposure to bullying in the workplace is positively correlated with self-reported health problems. However, these studies do not provide a basis to draw conclusions on the extent to which bullying leads to increased health problems or whether health problems increase the risk of being bullied. To provide better indications of a causal relationship, knowledge from prospective studies on the association between bullying in the workplace and health outcomes is therefore summarised.
  
  
  METHODS
  We conducted a systematic literature review of original articles from central literature databases on longitudinal associations between bullying in the workplace and health. Average associations between bullying and health outcomes are calculated using meta-analysis.
  
  
  RESULTS
  A consistent finding across the studies is that exposure to bullying is significantly positively related to mental health problems (OR =1.68; 95% KI 1.35-2.09) and somatic symptoms (OR = 1.77; 95% KI 1.41-2.22) over time. Mental health problems are also associated with subsequent exposure to bullying (OR = 1.74; 95% KI 1.44-2.12).
  
  
  CONCLUSIONS
  Bullying is positively related to mental health problems and somatic symptoms. The association between mental health problems and subsequent bullying indicates a self-reinforcing process between mental health and bullying. The methodological quality of the studies that were conducted is relatively sound. However, based on the existing knowledge base there are no grounds for conclusions regarding an unambiguous causal relationship between bullying and health.
authors.affiliation: Statens arbeidsmiljøinstitutt og Institutt for samfunnspsykologi Universitetet i Bergen.
authors.forename: Morten Birkeland
authors.initials: MB
authors.lastname: Nielsen
authors.affiliation: Yrkesmedisinsk avdeling Haukeland universitetssykehus.
authors.forename: Nils
authors.initials: N
authors.lastname: Magerøy
authors.affiliation: Statens arbeidsmiljøinstitutt og Institutt for biovitenskap Universitetet i Oslo.
authors.forename: Johannes
authors.initials: J
authors.lastname: Gjerstad
authors.affiliation: Institutt for samfunnspsykologi Universitetet i Bergen.
authors.forename: Ståle
authors.initials: S
authors.lastname: Einarsen
mesh_terms: D058445:Bullying / Q000523:psychology*; D006801:Humans; D001523:Mental Disorders / Q000209:etiology*; D009784:Occupational Diseases / Q000209:etiology / Q000523:psychology; D017132:Workplace / Q000523:psychology*