Development of a multidimensional measure of fibromyalgia symptomatology: the comprehensive rating scale for fibromyalgia symptomatology.

OBJECTIVE: Fibromyalgia (FM) is characterized by a heterogeneous group of clinical symptoms that are evaluated using a wide variety of instruments. This study sought to develop and validate a new scale, the Comprehensive Rating Scale for Fibromyalgia Symptomatology (CRSFS), to facilitate the joint evaluation of the most frequent symptoms in patients with FM.

METHODS: CRSFS items were based on a literature review and a focus group composed of patients and healthcare professionals. Four samples of patients (FM, non-FM rheumatic pain, depression, and healthy volunteers) were used to study the reliability and validity of the CRSFS. The factor structure of the CRSFS was determined through exploratory and confirmatory factor analyses. The test-retest and inter-examiner reliabilities were evaluated in a subsample of participants with FM. The criterion and convergent construct validity were compared using valid and reliable instruments to assess the impact of FM on quality of life, pain, fatigue, mood, and quality of sleep. The capacity to differentiate groups of patients was examined by comparing the CRSFS scores of the four samples to each other and using receiver operating characteristics curves.

RESULTS: The sample was composed of 240 participants, the mean age was 49.1years (SD=10.4), and 97.5% of them were women. The factor analyses, as well as the tests of reliability and validity, were positive. The final version of the CRSFS consisted of 20 symptoms evaluated using 60 items.

CONCLUSION: The CRSFS is a valid and reliable 4-factor scale that evaluates the most frequent clinical symptoms of patients with FM.