Development of a self-reporting tool to obtain a Combined Index of Severity of Fibromyalgia (ICAF*)

BACKGROUND: Fibromyalgia is a syndrome with heterogeneous symptoms. The evaluation in the clinical setting usually fails to cover the complexity of the syndrome. This study aims to determine how different aspects of fibromyalgia are inter-related when measured by means of a self-reporting tool. The objective is to develop a more complete evaluation model adjusted to the complexity and multi-dimensional nature of the syndrome. METHODS: Application was made of the Fibromyalgia Impact Questionnaire, the Hospital Anxiety and Depression Scale, the Brief Pain Inventory, the Fatigue Assessment Scale, the Health Assessment Questionnaire, the General Health Questionnaire (GHQ-28), the Chronic Pain Coping Inventory, the Arthritis Self-efficacy Scale and the Sleep Quality Scale. An assessment was made, on the basis of clinical interviews, case histories and specific tests, of the patient sociodemographic data, comorbidity, physical exploration and other clinical indexes. An exploratory factor analysis was made, with comparisons of the clinical index scores in extreme groups of patients. RESULTS: The ICAF composed of 59 items was obtained, offering four factors that explain 64% of the variance, and referred to as Emotional Factor (33.7%), Physical-Activity (15%), Active Coping (9%) and Passive Coping (6.3%). A t-test between the extreme scores of these factors in the 301 patients revealed statistically significant differences in occupational status, medically unexplained syndromes, number of tender points, the six-minutes walk test, comorbidity and health care costs. CONCLUSIONS: This study offers a tool allowing more complete and rapid evaluation of patients with fibromyalgia. The test intrinsically evaluates the emotional aspects: anxiety and depression, and their impact upon social aspects. It also evaluates patient functional capacity, fatigue, sleep quality, pain, and the way in which the patient copes with the disease. This is achieved by means of a self-assessment questionnaire based on elements from well known tests.