title: Does problem behaviour affect attrition from a cohort study on adolescent mental health?
abstract: BACKGROUND
  Most surveys are plagued by significant numbers of non-respondents. In psychiatric epidemiology, differences in levels of psychopathology are often assumed between respondents and non-respondents. However, studies on attrition are rare, especially in child and adolescent populations. The present study sought to estimate the association of depression, anti-social behaviour with attrition from a cohort study among adolescents.
  
  
  METHODS
  The adolescent mental health cohort study (AMHC) is a prospective follow-up study on prevalence and determinants of mental health problems and risk behaviour among Finnish adolescents at two study sites. Subjects of the final baseline sample (n = 3278) were reached for a 2-year follow-up. Differences in data collecting methods between the study sites yielded different response rates (78% vs. 51%). Chi-square statistics and logistic regression models were computed to estimate the effect of two types of problem behaviour on attrition.
  
  
  RESULTS
  Depression at baseline was associated with higher probability of attrition at follow-up. School performance was a stronger predictor of attrition than problem behaviour. The models predicted non-response in the study site with mainly school-based surveys but not in the study site with mainly postal surveys.
  
  
  CONCLUSIONS
  Internalizing problem behaviour may be underrepresented in adolescent mental health surveys. School performance is strongly associated with attrition. Hence, special attention should be paid to designing questionnaires targeting adolescents.
authors.affiliation: Tampere School of Public Health, University of Tampere, Tampere, Finland. sari.frojd@uta.fi
authors.forename: Sari A
authors.initials: SA
authors.lastname: Fröjd
authors.forename: Riittakerttu
authors.initials: R
authors.lastname: Kaltiala-Heino
authors.forename: Mauri J
authors.initials: MJ
authors.lastname: Marttunen
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology*; D000987:Antisocial Personality Disorder / Q000523:psychology*; D015331:Cohort Studies; D003866:Depressive Disorder / Q000523:psychology*; D004522:Educational Status; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010352:Patient Dropouts / Q000706:statistics & numerical data*; D011446:Prospective Studies; D012919:Social Behavior; D011795:Surveys and Questionnaires