Practical implications of item response theory and computerized adaptive testing: a brief summary of ongoing studies of widely used headache impact scales.

We have the potential to substantially advance the field of health status assessment by constructing and calibrating questionnaires based on item response theory (IRT) and administering them using computerized adaptive methods. This opportunity could hardly come at a better time. The health care industry needs more practical tools to monitor population health on a large scale as well as more precise tools to identify those who need and are most likely to benefit from treatment. Furthermore, we need to standardize the concepts and metrics of health sufficiently to permit comparisons of results across assessment tools and across diverse applications. To achieve the full potential of IRT models, many methodological issues must be addressed, including those raised by Hays et al1 and McHorney and Cohen.2 In responding to these authors, we have chosen to emphasize the practical implications of IRT models, particularly their usefulness for purposes of computerized adaptive health assessments. We briefly summarize ongoing efforts to calibrate and dynamically administer widely used measures of headache impact, note similarities and differences in our analytic approaches, and comment on the implications of IRT methodology.