title: Mental and somatic health complaints associated with school bullying between 10th and 12th grade students; results from cross sectional studies in Oslo, Norway.
abstract: BACKGROUND
  Bullying is a widespread and serious problem that might influence both mental and psychical well being as well as school performance and social life. The aim of this study was to describe the prevalence of bullying, mental health problems and psychical complaints among 10th and 12th grade students and to analyze the association between bullying, mental health problems and muscle and skeletal complaints.
  
  
  METHODS
  Two cross sectional studies of adolescents living in Oslo, Norway the first conducted in 2001 among 10th grade students (15/16 years old) and the second in 2004 among 12th grade students (18/19 years old). Both surveys were based on self report, were mostly school based and had almost identical questionnaires. There were around 3700 participants in both surveys, but the participation rate was lower in the latter survey (88 versus 80%). The Hopkins Symptoms Check List (HSCL-10) and the Strength and Difficulties Questionnaire (SDQ) were used to measure mental health problems.
  
  
  RESULTS
  Bullying is decreasing both among boys and girls while the prevalence of internalized mental health problems are increasing from 10th to 12th grade. For muscle and skeletal pain there is a diverging trend between boys and girls, with an increase among girls and a decrease among boys. The highest Odds Ratios, as a measure for the association between bullying, mental health problems and pain, were found for internalized mental health problems at both 10th and 12th grade both for boys and girls.
  
  
  CONCLUSIONS
  Both internalized and externalized mental health problems together with pain seem to be associated with bullying irrespective of school type and gender.
authors.affiliation: Institute of Psychiatry, University of Oslo, Box 1130, 0318 Oslo, Norway. lars.lien@medisin.uio.no.
authors.forename: Lars
authors.initials: L
authors.lastname: Lien
authors.forename: Kristian
authors.initials: K
authors.lastname: Green
authors.forename: Audun
authors.initials: A
authors.lastname: Welander-Vatn
authors.forename: Espen
authors.initials: E
authors.lastname: Bjertness