title: IRT health outcomes data analysis project: an overview and summary.
abstract: BACKGROUND
  In June 2004, the National Cancer Institute and the Drug Information Association co-sponsored the conference, "Improving the Measurement of Health Outcomes through the Applications of Item Response Theory (IRT) Modeling: Exploration of Item Banks and Computer-Adaptive Assessment." A component of the conference was presentation of a psychometric and content analysis of a secondary dataset.
  
  
  OBJECTIVE
  A thorough psychometric and content analysis was conducted of two primary domains within a cancer health-related quality of life (HRQOL) dataset.
  
  
  METHODS
  HRQOL scales were evaluated using factor analysis for categorical data, IRT modeling, and differential item functioning analyses. In addition, computerized adaptive administration of HRQOL item banks was simulated, and various IRT models were applied and compared.
  
  
  METHODS
  The original data were collected as part of the NCI-funded Quality of Life Evaluation in Oncology (Q-Score) Project. A total of 1,714 patients with cancer or HIV/AIDS were recruited from 5 clinical sites.
  
  
  METHODS
  Items from 4 HRQOL instruments were evaluated: Cancer Rehabilitation Evaluation System-Short Form, European Organization for Research and Treatment of Cancer Quality of Life Questionnaire, Functional Assessment of Cancer Therapy and Medical Outcomes Study Short-Form Health Survey.
  
  
  CONCLUSIONS
  Four lessons learned from the project are discussed: the importance of good developmental item banks, the ambiguity of model fit results, the limits of our knowledge regarding the practical implications of model misfit, and the importance in the measurement of HRQOL of construct definition. With respect to these lessons, areas for future research are suggested. The feasibility of developing item banks for broad definitions of health is discussed.
authors.affiliation: Department of Rehabilitation Medicine, University of Washington School of Medicine, Seattle, Washington, USA. karonc2@u.washington.edu
authors.forename: Karon F
authors.initials: KF
authors.lastname: Cook
authors.forename: Cayla R
authors.initials: CR
authors.lastname: Teal
authors.forename: Jakob B
authors.initials: JB
authors.lastname: Bjorner
authors.forename: David
authors.initials: D
authors.lastname: Cella
authors.forename: Chih-Hung
authors.initials: CH
authors.lastname: Chang
authors.forename: Paul K
authors.initials: PK
authors.lastname: Crane
authors.forename: Laura E
authors.initials: LE
authors.lastname: Gibbons
authors.forename: Ron D
authors.initials: RD
authors.lastname: Hays
authors.forename: Colleen A
authors.initials: CA
authors.lastname: McHorney
authors.forename: Katja
authors.initials: K
authors.lastname: Ocepek-Welikson
authors.forename: Anastasia E
authors.initials: AE
authors.lastname: Raczek
authors.forename: Jeanne A
authors.initials: JA
authors.lastname: Teresi
authors.forename: Bryce B
authors.initials: BB
authors.lastname: Reeve
mesh_terms: D003627:Data Interpretation, Statistical; D005260:Female; D015658:HIV Infections / Q000523:psychology; D006304:Health Status; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000523:psychology; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011594:Psychometrics; D011788:Quality of Life; D012984:Software; D013315:Stress, Psychological; D011795:Surveys and Questionnaires