Valid and accurate assessment of health-related outcomes is crucial in both clinical research and routine clinical practice. Especially the assessment of the patient’s perspective on health outcomes has received growing attention in all areas of health and medical research. Standardized questionnaires, so-called patient-reported outcomes (PROs), are now are now widely accepted as major endpoints in many fields of medicine. Moreover, drug regulatory agencies such the US Food and Drug Administration (FDA) and the European Medicines Agency (EMEA), increasingly stress the need for and additional value of using PROs in supporting labeling claims about the efficacy of medical products.
However, current outcome measures are far from perfect. Measures are often either too long, which limits their use in clinical practice and places a large burden on respondents, or too short to provide the necessary measurement precision in clinical trials. Contemporary statistical and measurement methods, such as item response theory (IRT) and computer adaptive testing (CAT), have the ability to maximize precision and, at the same time, minimize response burden. For instance, recent project such as the NIH-sponsored Patient Reported Outcomes Measurement Information System (PROMIS) project, demonstrated that the number of required items for a PRO could be reduced up to 70% using IRT and CAT without any loss in measurement precision. Additionally, the increased measurement precision of PROs based on CAT will reduce the number of patients required for clinical trials while holding statistical power constant.
Since IRT and CAT have shown to be powerful tools for developing better health-related outcome measures, many health researchers and clinicians are becoming increasingly interested in this new approach to health measurement. The aim of this symposium is to acquaint those people with the basic issues involved in IRT analysis and CAT development and provide examples of state-of-art projects in different medical areas.