title: Functioning and validity of a Computerized Adaptive Test to measure anxiety (A-CAT).
abstract: BACKGROUND
  The aim of this study was to evaluate the Computerized Adaptive Test to measure anxiety (A-CAT), a patient-reported outcome questionnaire that uses computerized adaptive testing to measure anxiety.
  
  
  METHODS
  The A-CAT builds on an item bank of 50 items that has been built using conventional item analyses and item response theory analyses. The A-CAT was administered on Personal Digital Assistants to n=357 patients diagnosed and treated at the department of Psychosomatic Medicine and Psychotherapy, Charité Berlin, Germany. For validation purposes, two subgroups of patients (n=110 and 125) answered the A-CAT along with established anxiety and depression questionnaires.
  
  
  RESULTS
  The A-CAT was fast to complete (on average in 2 min, 38 s) and a precise item response theory based CAT score (reliability>.9) could be estimated after 4-41 items. On average, the CAT displayed 6 items (SD=4.2). Convergent validity of the A-CAT was supported by correlations to existing tools (Hospital Anxiety and Depression Scale-A, Beck Anxiety Inventory, Berliner Stimmungs-Fragebogen A/D, and State Trait Anxiety Inventory: r=.56-.66); discriminant validity between diagnostic groups was higher for the A-CAT than for other anxiety measures.
  
  
  CONCLUSIONS
  The German A-CAT is an efficient, reliable, and valid tool for assessing anxiety in patients suffering from anxiety disorders and other conditions with significant potential for initial assessment and long-term treatment monitoring. Future research directions are to explore content balancing of the item selection algorithm of the CAT, to norm the tool to a healthy sample, and to develop practical cutoff scores.
authors.affiliation: Department of Psychosomatic Medicine and Psychotherapy, Charité Universitätsmedizin, Berlin, Germany. janine.becker@charite.de
authors.forename: Janine
authors.initials: J
authors.lastname: Becker
authors.forename: Herbert
authors.initials: H
authors.lastname: Fliege
authors.forename: Rüya-Daniela
authors.initials: RD
authors.lastname: Kocalevent
authors.forename: Jakob B
authors.initials: JB
authors.lastname: Bjorner
authors.forename: Matthias
authors.initials: M
authors.lastname: Rose
authors.forename: Otto B
authors.initials: OB
authors.lastname: Walter
authors.forename: Burghard F
authors.initials: BF
authors.lastname: Klapp
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001008:Anxiety Disorders / Q000175:diagnosis* / Q000523:psychology; D015897:Comorbidity; D034201:Computers, Handheld; D003866:Depressive Disorder / Q000175:diagnosis / Q000523:psychology; D003936:Diagnosis, Computer-Assisted; D005260:Female; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis / Q000523:psychology; D008875:Middle Aged; D015233:Models, Statistical; D010555:Personality Inventory / Q000706:statistics & numerical data*; D011594:Psychometrics / Q000706:statistics & numerical data; D011602:Psychophysiologic Disorders / Q000175:diagnosis / Q000523:psychology; D015203:Reproducibility of Results; D012984:Software; D055815:Young Adult