TY - JOUR T1 - Measuring global physical health in children with cerebral palsy: Illustration of a multidimensional bi-factor model and computerized adaptive testing JF - Quality of Life Research Y1 - 2009 A1 - Haley, S. M. A1 - Ni, P. A1 - Dumas, H. M. A1 - Fragala-Pinkham, M. A. A1 - Hambleton, R. K. A1 - Montpetit, K. A1 - Bilodeau, N. A1 - Gorton, G. E. A1 - Watson, K. A1 - Tucker, C. A. KW - *Computer Simulation KW - *Health Status KW - *Models, Statistical KW - Adaptation, Psychological KW - Adolescent KW - Cerebral Palsy/*physiopathology KW - Child KW - Child, Preschool KW - Factor Analysis, Statistical KW - Female KW - Humans KW - Male KW - Massachusetts KW - Pennsylvania KW - Questionnaires KW - Young Adult AB - PURPOSE: The purposes of this study were to apply a bi-factor model for the determination of test dimensionality and a multidimensional CAT using computer simulations of real data for the assessment of a new global physical health measure for children with cerebral palsy (CP). METHODS: Parent respondents of 306 children with cerebral palsy were recruited from four pediatric rehabilitation hospitals and outpatient clinics. We compared confirmatory factor analysis results across four models: (1) one-factor unidimensional; (2) two-factor multidimensional (MIRT); (3) bi-factor MIRT with fixed slopes; and (4) bi-factor MIRT with varied slopes. We tested whether the general and content (fatigue and pain) person score estimates could discriminate across severity and types of CP, and whether score estimates from a simulated CAT were similar to estimates based on the total item bank, and whether they correlated as expected with external measures. RESULTS: Confirmatory factor analysis suggested separate pain and fatigue sub-factors; all 37 items were retained in the analyses. From the bi-factor MIRT model with fixed slopes, the full item bank scores discriminated across levels of severity and types of CP, and compared favorably to external instruments. CAT scores based on 10- and 15-item versions accurately captured the global physical health scores. CONCLUSIONS: The bi-factor MIRT CAT application, especially the 10- and 15-item versions, yielded accurate global physical health scores that discriminated across known severity groups and types of CP, and correlated as expected with concurrent measures. The CATs have potential for collecting complex data on the physical health of children with CP in an efficient manner. VL - 18 SN - 0962-9343 (Print)0962-9343 (Linking) N1 - Haley, Stephen MNi, PengshengDumas, Helene MFragala-Pinkham, Maria AHambleton, Ronald KMontpetit, KathleenBilodeau, NathalieGorton, George EWatson, KyleTucker, Carole AK02 HD045354-01A1/HD/NICHD NIH HHS/United StatesK02 HD45354-01A1/HD/NICHD NIH HHS/United StatesResearch Support, N.I.H., ExtramuralResearch Support, Non-U.S. Gov'tNetherlandsQuality of life research : an international journal of quality of life aspects of treatment, care and rehabilitationQual Life Res. 2009 Apr;18(3):359-70. Epub 2009 Feb 17. U2 - 2692519 ER -