title: Psychometric evaluation of the EORTC computerized adaptive test (CAT) fatigue item pool.
abstract: OBJECTIVE
  Fatigue is one of the most common symptoms associated with cancer and its treatment. To obtain a more precise and flexible measure of fatigue, the EORTC Quality of Life Group has developed a computerized adaptive test (CAT) measure of fatigue. This is part of an ongoing project developing a CAT version of the widely used EORTC QLQ-C30 questionnaire.
  
  
  METHODS
  Based on the literature search and evaluations by experts and patients, 41 new fatigue items were developed (in addition to the three QLQ-C30 fatigue items). Psychometric properties of the items, including evaluations of dimensionality, fit to item response theory (IRT) model, and differential item functioning (DIF), were assessed in an international sample of cancer patients.
  
  
  RESULTS
  Responses were obtained from 1,321 cancer patients coming from eight countries. Factor analysis showed that 37 of the items could be included in a unidimensional model (RMSEA = 0.098, TLI = 0.995, CFI = 0.920). Of the 37 items, two were deleted because of poor fit to the IRT model forming the basis for the CAT, and one because of DIF between cancer sites.
  
  
  CONCLUSIONS
  We have established a 34-item fatigue bank allowing for more precise and flexible measurement of fatigue, while still being backward compatible with the QLQ-C30 fatigue scale.
authors: The Research Unit, Department of Palliative Medicine, Bispebjerg University Hospital, Bispebjerg bakke 23, 2400, Copenhagen, NV, Denmark, mpet0009@bbh.regionh.dk.
authors: Morten Aa
authors: MA
authors: Petersen
authors: Johannes M
authors: JM
authors: Giesinger
authors: Bernhard
authors: B
authors: Holzner
authors: Juan I
authors: JI
authors: Arraras
authors: Thierry
authors: T
authors: Conroy
authors: Eva-Maria
authors: EM
authors: Gamper
authors: Madeleine T
authors: MT
authors: King
authors: Irma M
authors: IM
authors: Verdonck-de Leeuw
authors: Teresa
authors: T
authors: Young
authors: Mogens
authors: M
authors: Groenvold
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005163:Factor Analysis, Statistical; D005221:Fatigue / Q000145:classification* / Q000175:diagnosis / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D011594:Psychometrics / Q000295:instrumentation*; D011788:Quality of Life; D012984:Software; D011795:Surveys and Questionnaires; D055815:Young Adult