Background Fibromyalgia (FM) can coexist with Spondyloarthritis (SpA) leading to diagnostic and treatment dilemmas, especially in the presence of enthesitis. The Fibromyalgia Rapid Screening Tool (FiRST) is a self-reported questionnaire, independent from tender points, which can be used for FM screening1.
Objectives To estimate the prevalence of FM in a SpA cohort according to the FiRST, to compare the prevalence of FM with regard to the fulfilment of the ASAS classification criteria, to compare the clinical/disease features and TNFi treatment in terms of initiation and first TNFi retention rate, in patients with/without FM respectively.
Methods Patients: SpA patients (according to the rheumatologist) consecutively consulting on a tertiary care hospital. FM definition: according to the FiRST questionnaire, patients answering “yes” at ≥5/6 questions were considered FM+. Data collection: All patients completed the FiRST questionnaire. Demographics, patients/disease characteristics, activity/severity and TNFi initiation as well as the retention of the first TNFi treatment, were collected. Statistical analysis: The percentage of FM+ according to the FiRST was calculated in the global population and in the different arms of the ASAS criteria. Demographics, disease characteristics, activity and severity were compared in FM+ and FM- groups. The percentage of patients ever initiating a TNFi was compared in both groups. The retention rate of the first TNFi in both groups was estimated by Kaplan-Meier curves and tested by the Log-rank test. Predisposing factors for first TNFi retention rate were estimated by Cox models.
Results Of the 222 patients who completed the FiRST questionnaire, 195 were included for the analysis, among them 42 (21.5%) fulfilled the FM definition. From the total, 185 (94.8%) met the ASAS criteria with a similar % of FM in the different subgroups [e.g imaging (21.5%) and clinical (18.7%), p=NS]. Patients fulfilling the FM definition presented with more enthesitis (59.5% vs.39.5%, p=0.02), more frequent history of depression (41.0% vs.18.4%, p<0.01), higher total BASDAI [4.6 (±2.3) vs. 2.6 (±2.0), p<0.01] and BASFI [4.8 (±3.7) vs. 2.0 (±1.5), p<0.01]. Furthermore, patients in this group reported more frequently analgesics (92.7%vs.72%, p<0.01) and psychotropic medications (e.g. myorelaxant or antidepressants or anxiolytic or strong opioids) (66.7%vs.35.9%,p<0.01). Regarding TNFi treatment, TNFi were initiated in 79%vs.70% in FM+ and FM- groups, respectively (p=NS). The retention rate of the first TNFi was significantly shorter in the FM+ group. After 1 and 2 years, 55%vs.50% and 28.1%vs.41.2% of patients were still under treatment in the FM+vs.FM- groups, respectively,(Cox p=0.03).
Conclusions Our study suggests the following:1) the similar percentage of FM in the imaging and clinical arms of the ASAS criteria is an argument in favor of the validity of these criteria; 2) the coexistance of FM might impact the score of the instrument used to evaluate disease activity and also the retention rate of the TNFi treatment.
Perrot S, Bouhassira D, Fermanian J. Development and validation of the Fibromyalgia Rapid Screening Tool (FiRST). Pain 150,250–256 (2010).
Acknowledgements N.B wishes to acknowledge to the Spanish Rheumatology Foundation (FER) for a training bursary.
Disclosure of Interest None declared