@article {312,
	title = {Development of computerized adaptive testing (CAT) for the EORTC QLQ-C30 physical functioning dimension},
	journal = {Quality of Life Research },
	volume = {20},
	number = {4},
	year = {2010},
	note = {Qual Life Res. 2010 Oct 23.},
	pages = {479-490},
	edition = {2010/10/26},
	abstract = {PURPOSE: Computerized adaptive test (CAT) methods, based on item response theory (IRT), enable a patient-reported outcome instrument to be adapted to the individual patient while maintaining direct comparability of scores. The EORTC Quality of Life Group is developing a CAT version of the widely used EORTC QLQ-C30. We present the development and psychometric validation of the item pool for the first of the scales, physical functioning (PF). METHODS: Initial developments (including literature search and patient and expert evaluations) resulted in 56 candidate items. Responses to these items were collected from 1,176 patients with cancer from Denmark, France, Germany, Italy, Taiwan, and the United Kingdom. The items were evaluated with regard to psychometric properties. RESULTS: Evaluations showed that 31 of the items could be included in a unidimensional IRT model with acceptable fit and good content coverage, although the pool may lack items at the upper extreme (good PF). There were several findings of significant differential item functioning (DIF). However, the DIF findings appeared to have little impact on the PF estimation. CONCLUSIONS: We have established an item pool for CAT measurement of PF and believe that this CAT instrument will clearly improve the EORTC measurement of PF.},
	isbn = {1573-2649 (Electronic)0962-9343 (Linking)},
	author = {Petersen, M. A. and Groenvold, M. and Aaronson, N. K. and Chie, W. C. and Conroy, T. and Costantini, A. and Fayers, P. and Helbostad, J. and Holzner, B. and Kaasa, S. and Singer, S. and Velikova, G. and Young, T.}
}
@article {311,
	title = {Multidimensional computerized adaptive testing of the EORTC QLQ-C30: basic developments and evaluations},
	journal = {Quality of Life Research},
	volume = {15},
	number = {3},
	year = {2006},
	note = {Petersen, Morten AaGroenvold, MogensAaronson, NeilFayers, PeterSprangers, MirjamBjorner, Jakob BEuropean Organisation for Research and Treatment of Cancer Quality of Life GroupResearch Support, Non-U.S. Gov{\textquoteright}tNetherlandsQuality of life research : an international journal of quality of life aspects of treatment, care and rehabilitationQual Life Res. 2006 Apr;15(3):315-29.},
	month = {Apr},
	pages = {315-29},
	edition = {2006/03/21},
	abstract = {OBJECTIVE: Self-report questionnaires are widely used to measure health-related quality of life (HRQOL). Ideally, such questionnaires should be adapted to the individual patient and at the same time scores should be directly comparable across patients. This may be achieved using computerized adaptive testing (CAT). Usually, CAT is carried out for a single domain at a time. However, many HRQOL domains are highly correlated. Multidimensional CAT may utilize these correlations to improve measurement efficiency. We investigated the possible advantages and difficulties of multidimensional CAT. STUDY DESIGN AND SETTING: We evaluated multidimensional CAT of three scales from the EORTC QLQ-C30: the physical functioning, emotional functioning, and fatigue scales. Analyses utilised a database with 2958 European cancer patients. RESULTS: It was possible to obtain scores for the three domains with five to seven items administered using multidimensional CAT that were very close to the scores obtained using all 12 items and with no or little loss of measurement precision. CONCLUSION: The findings suggest that multidimensional CAT may significantly improve measurement precision and efficiency and encourage further research into multidimensional CAT. Particularly, the estimation of the model underlying the multidimensional CAT and the conceptual aspects need further investigations.},
	keywords = {*Quality of Life, *Self Disclosure, Adult, Female, Health Status, Humans, Male, Middle Aged, Questionnaires/*standards, User-Computer Interface},
	isbn = {0962-9343 (Print)},
	author = {Petersen, M. A. and Groenvold, M. and Aaronson, N. K. and Fayers, P. and Sprangers, M. and Bjorner, J. B.}
}
