Using item response theory to enrich and expand the PROMIS® pediatric self report banks

BACKGROUND The primary objective was to enhance the content coverage of some of the pediatric self-report item banks for ages 8-17 years from the National Institutes of Health (NIH) Patient Reported Outcomes Measurement Information System (PROMIS®), and extend the range of precise measurement to higher levels of physical functioning. METHODS Data from 1,419 pediatric patients with cancer, chronic kidney disease, obesity, rehabilitation needs, rheumatic disease, and sickle cell disease were combined with item responses from the original standardization sample of 3,048 children to calibrate new items for the pediatric PROMIS Anger, Anxiety, Depressive Symptoms, Pain Interference, Fatigue, and physical functioning Upper Extremity and Mobility scales. Simultaneous or concurrent calibration using the graded item response theory model placed all of the items on the same scale. RESULTS Twenty-two of 28 potential new items were added across the seven scales. A recommended short form was proposed for the Anger scale, and the recommended short forms for the Anxiety and Depressive Symptoms scales were revised. Unfortunately, we were not particularly successful at extending the range of measurement for the physical functioning banks. CONCLUSIONS The present study expanded PROMIS pediatric item banks to add new content and to increase the range of measurement. Using item response theory, the banks were revised and expanded without changing the underlying scale of measurement. For Anger, Anxiety, and Depressive Symptoms, we successfully added new content that may render those banks more robust and flexible.