title: Attrition bias in longitudinal research involving adolescent psychiatric outpatients.
abstract: This study investigated whether the degree of difficulty contacting participants at follow-up in a longitudinal study of adolescent psychiatric outpatients is associated with baseline and/or follow-up Axis I and II psychopathology and sociodemographic variables. At baseline, 101 participants 15 to 18 years old were assessed using standardized diagnostic instruments, and 97 were reinterviewed, face-to-face, at 2-year follow-up. A hierarchical tracking strategy and meticulous follow-up contact log were used. More than one quarter of the sample required multiple tracking efforts to be located and interviewed. The presence and number of Axis I and II disorders at 2-year follow-up was significantly associated with follow-up contact difficulty. Baseline psychopathology and sociodemographic variables were not associated with follow-up contact difficulty. The findings indicate that longitudinal studies of adolescent outpatients that compare dropouts with completers utilizing baseline characteristics are likely to underestimate the extent of psychopathology at follow-up.
authors.affiliation: ORYGEN Research Centre, Department of Psychiatry, University of Melbourne, Melbourne, Australia. kallott@unimelb.edu.au
authors.forename: Kelly
authors.initials: K
authors.lastname: Allott
authors.forename: Andrew
authors.initials: A
authors.lastname: Chanen
authors.forename: Hok Pan
authors.initials: HP
authors.lastname: Yuen
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000553:Ambulatory Care; D001315:Australia / Q000453:epidemiology; D003625:Data Collection / Q000379:methods / Q000706:statistics & numerical data*; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D001523:Mental Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D010352:Patient Dropouts / Q000706:statistics & numerical data*; D018579:Patient Selection; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D015983:Selection Bias