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Erschienen in:
01.08.2007 | Original Paper
IRT health outcomes data analysis project: an overview and summary
Erschienen in: Quality of Life Research | Sonderheft 1/2007
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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.
Objectives
A thorough psychometric and content analysis was conducted of two primary domains within a cancer health-related quality of life (HRQOL) dataset.
Research design
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.
Subjects
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.
Measures
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.
Results and 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.