Background: Diagnosis of SpA in the absence of objective signs of inflammation or structural damage can be challenging, and especially difficult to differentiate from Fibromyalgia. Furthermore, such patients can easily be classified as active and refractory to NSAIDs, and inappropriately receive TNF alpha blockers.~Objective: Primary objective: To evaluate the impact of fibromyalgia in the TNF alpha treatment effect in axial Spondyloarthritis in both anti-TNF naïve and - experienced patients.~Methods: Design: Prospective observational national (France) study with 2 visits 3 months apart (baseline and 12 weeks after TNF alpha blockers initiation). Patients: 500 SpA patients (diagnosis according to their treating rheumatologist) initiating a TNF alpha blocker. Data collection: items permitting the calculation of the ASAS criteria, the FIRST questionnaire (Fibromyalgia Rapid Screen Test), patients and disease characteristics, disease activity and severity items, and the domain leading the doctor's decision for initiating the TNF alpha blocker (CRP/Imaging/Symptoms) will be collected at baseline. Effectiveness measures (e.g. BASDAI and patient's global) and the doctor's decision to continue/discontinue the TNF alpha blocker will be collected during the second visit. Statistical analysis: for the main objective, evaluation of the predictive factors of a TNF alpha response in real life, and the impact of Fibromyalgia in such response (e.g. logistic regression to estimate BASDAI reduction of 50%). For the secondary objectives: evaluation of the relative attributable risks of the doctor's domains leading the TNF alpha blocker initiation (Imaging/CRP/Symptoms) in order to explain the anti-TNF therapy response; evaluation of the concordance existing between the current recommendations and the daily practice.~Expected results: A positive finding might results into a change in the way of managing patients (e.g. carefully checking for the co-existence of fibromyalgia before confirming a spondyloarthritis diagnosis, an active disease and also before initiating a specific therapy such as biologics.
This is a prospective observational national (France) study with 2 visits 3 months apart (baseline and 12 weeks after TNF alpha blockers initiation). The objective of recruitment is 500 SpA patients (diagnosis according to their treating rheumatologist) initiating a TNF alpha blocker.~The main objective of the study is to evaluate the impact of a concomitant fibromyalgia on the anti-TNF treatment effect in axial Spondyloarthritis in both anti-TNF naïve and pre-exposed patients.