Calibration of an item pool for assessing the burden of headaches: an application of item response theory to the headache impact test (HIT)
Department of Quantitative Health Sciences
Medical Subject Headings
Adolescent; Adult; Aged; Calibration; Disabled Persons; Factor Analysis, Statistical; Headache; Humans; Middle Aged; Quality of Life; Questionnaires; *Sickness Impact Profile
Biostatistics | Epidemiology | Health Services Research
BACKGROUND: 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.
OBJECTIVE: To develop an item pool that can be used for a computerized adaptive test of headache impact.
METHODS: 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).
RESULTS: 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.
CONCLUSION: We have established a headache impact item pool that can be used in CAT of headache impact.
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Citation: Qual Life Res. 2003 Dec;12(8):913-33. Link to article on publisher's site
Bjorner, Jakob B.; Kosinski, Mark; and Ware, John E. Jr., "Calibration of an item pool for assessing the burden of headaches: an application of item response theory to the headache impact test (HIT)" (2003). Quantitative Health Sciences Publications and Presentations. 587.