title: Working mechanism of a multidimensional computerized adaptive test for fatigue in rheumatoid arthritis.
abstract: BACKGROUND
  This paper demonstrates the mechanism of a multidimensional computerized adaptive test (CAT) to measure fatigue in patients with rheumatoid arthritis (RA). A CAT can be used to precisely measure patient-reported outcomes at an individual level as items are consequentially selected based on the patient's previous answers. The item bank of the CAT Fatigue RA has been developed from the patients' perspective and consists of 196 items pertaining to three fatigue dimensions: severity, impact and variability of fatigue.
  
  
  METHODS
  The CAT Fatigue RA was completed by fifteen patients. To test the CAT's working mechanism, we applied the flowchart-check-method. The adaptive item selection procedure for each patient was checked by the researchers. The estimated fatigue levels and the measurement precision per dimension were illustrated with the selected items, answers and flowcharts.
  
  
  RESULTS
  The CAT Fatigue RA selected all items in a logical sequence and those items were selected which provided the most information about the patient's individual fatigue. Flowcharts further illustrated that the CAT reached a satisfactory measurement precision, with less than 20 items, on the dimensions severity and impact and to somewhat lesser extent also for the dimension variability. Patients' fatigue scores varied across the three dimensions; sometimes severity scored highest, other times impact or variability. The CAT's ability to display different fatigue experiences can improve communication in daily clinical practice, guide interventions, and facilitate research into possible predictors of fatigue.
  
  
  CONCLUSIONS
  The results indicate that the CAT Fatigue RA measures precise and comprehensive. Once it is examined in more detail in a consecutive, elaborate validation study, the CAT will be available for implementation in daily clinical practice and for research purposes.
authors.affiliation: Department of Psychology, Health and Technology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands. stephanie.nikolaus@radboudumc.nl.|Expert Center for Chronic Fatigue, Radboud University Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands. stephanie.nikolaus@radboudumc.nl.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Nikolaus
authors.affiliation: Department of Psychology, Health and Technology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands. c.bode@utwente.nl.
authors.forename: Christina
authors.initials: C
authors.lastname: Bode
authors.affiliation: Department of Psychology, Health and Technology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands. e.taal@utwente.nl.
authors.forename: Erik
authors.initials: E
authors.lastname: Taal
authors.affiliation: Department of Psychology, Health and Technology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands. h.vonkeman@mst.nl.|Medical Spectrum Twente, Department of Rheumatology and Clinical Immunology, P.O. Box 50 000, 7500 KA, Enschede, The Netherlands. h.vonkeman@mst.nl.
authors.forename: Harald E
authors.initials: HE
authors.lastname: Vonkeman
authors.affiliation: Department of Research Methodology, Measurement and Data Analysis, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands. c.a.w.glas@utwente.nl.
authors.forename: Cees A W
authors.initials: CA
authors.lastname: Glas
authors.affiliation: Department of Psychology, Health and Technology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands. m.vandelaar@mst.nl.|Medical Spectrum Twente, Department of Rheumatology and Clinical Immunology, P.O. Box 50 000, 7500 KA, Enschede, The Netherlands. m.vandelaar@mst.nl.
authors.forename: Mart A F J
authors.initials: MA
authors.lastname: van de Laar
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications* / Q000523:psychology; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005221:Fatigue / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life