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- Title
Calibration of an item pool for assessing the burden of headaches: an application of item response theory to the headache impact test (HIT).
- Authors
Bjorner, Jakob B.; Kosinski, Mark; Ware. Jr., John E.; Ware, John E Jr
- Abstract
<bold>Background: </bold>Measurement of headache impact is important in clinical trials, case detection, and the clinical monitoring of patients. Computerized adaptive testing (CAT) of headache impact has potential advantages over traditional fixed-length tests in terms of precision, relevance, real-time quality control and flexibility.<bold>Objective: </bold>To develop an item pool that can be used for a computerized adaptive test of headache impact.<bold>Methods: </bold>We analyzed responses to four well-known tests of headache impact from a population-based sample of recent headache sufferers (n = 1016). We used confirmatory factor analysis for categorical data and analyses based on item response theory (IRT).<bold>Results: </bold>In factor analyses, we found very high correlations between the factors hypothesized by the original test constructers, both within and between the original questionnaires. These results suggest that a single score of headache impact is sufficient. We established a pool of 47 items which fitted the generalized partial credit IRT model. By simulating a computerized adaptive health test we showed that an adaptive test of only five items had a very high concordance with the score based on all items and that different worst-case item selection scenarios did not lead to bias.<bold>Conclusion: </bold>We have established a headache impact item pool that can be used in CAT of headache impact.
- Subjects
HEADACHE; PSYCHOMETRICS; CLINICAL trials; ITEM response theory; PSYCHOLOGICAL tests
- Publication
Quality of Life Research, 2003, Vol 12, Issue 8, p913
- ISSN
0962-9343
- Publication type
journal article
- DOI
10.1023/A:1026163113446