Development and initial validation of a brief self-report measure of cognitive dysfunction in fibromyalgia

Pain is often the focus of research and clinical care in fibromyalgia (FM); however, cognitive dysfunction is also a common, distressing, and disabling symptom in FM. Current efforts to address this problem are limited by the lack of a comprehensive, valid measure of subjective cognitive dysfunction in FM that is easily interpretable, accessible, and brief. The purpose of this study was to leverage cognitive functioning item banks that were developed as part of the Patient Reported Outcomes Measurement Information System (PROMIS) to devise a 10-item short form measure of cognitive functioning for use in FM. In study 1, a nationwide (U.S.) sample of 1,035 adults with FM (age range = 18-82, 95.2% female) completed 2 cognitive item pools. Factor analyses and item response theory analyses were used to identify dimensionality and optimally performing items. A recommended 10-item measure, called the Multidimensional Inventory of Subjective Cognitive Impairment (MISCI) was created. In study 2, 232 adults with FM completed the MISCI and a legacy measure of cognitive functioning that is used in FM clinical trials, the Multiple Ability Self-Report Questionnaire (MASQ). The MISCI showed excellent internal reliability, low ceiling/floor effects, and good convergent validity with the MASQ (r = -.82).

This paper presents the MISCI, a 10-item measure of cognitive dysfunction in FM, developed through classical test theory and item response theory. This brief but comprehensive measure shows evidence of excellent construct validity through large correlations with a lengthy legacy measure of cognitive functioning.