Measurement of Quality of Life in Patients with Mycosis Fungoides/Sézary Syndrome Cutaneous T-Cell Lymphoma: Development of an Electronic Instrument

Background: Although the quality of life (QoL) plays an important role in treatment decision making and clinical management of mycosis fungoides (MF) or Sezary syndrome (SS) subtypes of cutaneous T-cell lymphomas (MF/SS-CTCLs), an MF- or SS-specific measure of QoL does not exist. Objective: The objective of this research was to develop and validate the first QoL instrument for MF/SS-CTCL using a patient-centered approach. Methods: A conceptual framework for the MF/SS-CTCL QoL was developed through a literature review and interviews with key opinion leaders. Concept elicitation with patients was utilized to refine the conceptual model and generate preliminary items. The items were then revised based on qualitative and quantitative feedback obtained through cognitive debriefing surveys and interviews with patients. Next, participants (N=126) completed the preliminary MF/SS-CTCL QoL and a comparator measure of health-related QoL (Skindex-29) through the PatientsLikeMe Open Research Exchange. The MF/SS-CTCL QoL was completed again 5 days later by 66 participants for the purposes of evaluating test-retest reliability. The MF/SS-CTCL QoL was finalized based on results from an empirical evaluation, which included both classical and modern test theory approaches. Specifically, this included evaluation of (1) the optimal item response theory measurement model; (2) item fit; (3) unidimensionality; (4) rating scale performance; (5) reliability; (6) test information (precision); (7) person-to-item map; (8) convergent and discriminant validity; and (9) presence of bias via differential item function. Results: Results from the comprehensive psychometric evaluation utilizing a Rasch-Grouped Rating Scale model yielded a final 12-item instrument. The rating scale functioned as expected, and the instrument exhibited adequate person reliability (.87), good to excellent test-retest reliability (r=.89, P