Development and testing of item response theory-based item banks and short forms for eye, skin and lung problems in sarcoidosis.

PURPOSE: Sarcoidosis is a multisystem disease that can negatively impact health-related quality of life (HRQL) across generic (e.g., physical, social and emotional wellbeing) and disease-specific (e.g., pulmonary, ocular, dermatologic) domains. Measurement of HRQL in sarcoidosis has largely relied on generic patient-reported outcome tools, with little disease-specific measures available. The purpose of this paper is to present the development and testing of disease-specific item banks and short forms of lung, skin and eye problems, which are a part of a new patient-reported outcome (PRO) instrument called the sarcoidosis assessment tool.
METHODS: After prioritizing and selecting the most important disease-specific domains, we wrote new items to reflect disease-specific problems by drawing from patient focus group and clinician expert survey data that were used to create our conceptual model of HRQL in sarcoidosis. Item pools underwent cognitive interviews by sarcoidosis patients (n = 13), and minor modifications were made. These items were administered in a multi-site study (n = 300) to obtain item calibrations and create calibrated short forms using item response theory (IRT) approaches.
RESULTS: From the available item pools, we created four new item banks and short forms: (1) skin problems, (2) skin stigma, (3) lung problems, and (4) eye Problems. We also created and tested supplemental forms of the most common constitutional symptoms and negative effects of corticosteroids.
CONCLUSIONS: Several new sarcoidosis-specific PROs were developed and tested using IRT approaches. These new measures can advance more precise and targeted HRQL assessment in sarcoidosis clinical trials and clinical practice.