Background Fibromyalgia (FM) is a frequent comorbid condition in axial spondyloarthritis (axSpA). It is not known how FM comorbidity may respond to the management of SpA, and especially to anti-TNF agents.
Objectives To evaluate the change of comorbid FM status of axSpA patients starting an anti-TNF treatment.
Methods A prospective multicenter national study involving 39 rheumatology centers in France, analyzing 519 patients with axSpA requiring anti-TNF therapy (ClinicalTrials.gov: NCT03039088). Patients were screened for FM with the FiRST questionnaire before and after 3 months of anti-TNF. Kappa coefficient was calculated to determine the agreement of the FiRST at M0 and M3. Response to anti-TNF (BASDAI50 response was compared according to positive screening for FM or not, at both time-points using chi2 tests.
Results Of the 519 enrolled pts, 504 (with complete data on the FiRST questionnaire) were analyzed at M3. A positive screening for comorbid FM was found in 192 pts (38%) at M0 and in 127 (25%) pts at M3. Correlation between FiRST at M0 and M3 was weak with a Kappa coefficient correlation of 0.4 [0,3 - 0,5].
Four groups were identified: group [+/+] with comorbid FM at M0 and M3: N=93 (18%; group [+/-] with comorbid FM at M0 but not at M3: N=99 (20%); group [-/-] without comorbid FM at M0 and M3: N=278 (55%); group [-/+] without comorbid FM at M0 but at M3: N=34 (7%)
Changes in the status of comorbid FM (disappearance or appearance) was observed in 134 pts (26%). In the 193 pts with baseline comorbid FM, after 3 months of anti-TNF treatment, comorbid FM was no longer found in 99 (51%)%.Efficacy at M3 was significantly better, according to BASDAI 50, in patients without comorbid FM at M3 (Table).
Conclusions There is a high frequency of comorbid FM screened by the FiRST in active axSpA, decreased by 51%f after 3 months of anti-TNF treatments. Persistence of FM after 3 months of anti-TNF treatment is associated with lower anti-TNF response. Further studies are required to analyze the impact of screening FM before starting anti-TNF therapy in axSpA.
Perrot S, et al. Development and validation of the Fibromyalgia Rapid Screening Tool (FiRST). Pain. 2010;150:250–6.
Acknowledgements This study was conducted thanks to an unrestricted grant from MSD.
Disclosure of Interest None declared