Characteristics of difficult-to-treat axial spondyloarthritis: Results of a real-world multicentric study.

OBJECTIVE

The EULAR task force recently published the difficult-to-treat RA (D2T RA) definition, however, a definition of D2T axSpA is still lacking and limitations in this definition exist. The objectives were to study the characteristics of D2T axSpA patients using the EULAR definition and to study a subgroup of patients with a predefined more stringent definition including a temporal criterion.

METHODS

A multicentric retrospective study was performed. D2T axSpA was defined as failure of≥2 b/tsDMARDs with different mechanism of action. Very D2T axSpA was defined as failure of≥2 b/tsDMARDs in less than 2 years of follow-up. D2T and Very D2T axSpA patients were compared to non-D2T (nD2T) axSpA patients.

RESULTS

Three hundred and eleven axSpA patients were included: 88 D2T axSpA (28.3%) and 223 non-D2T (nD2T) axSpA (71.7%). Peripheral involvement was more prevalent in the D2T group (34.9 vs. 21.4%; P=0.015). BASDAI level at baseline was higher in the D2T group (63.7±16.5 vs. 58.8±14.7; P=0.015). Fibromyalgia was found to be more frequent in the D2T group vs nD2T group (P<0.001). Twelve patients (3.8%) were categorized as very D2T axSpA. Compared to nD2T, Very D2T patients had a higher CRP level at baseline (42.0±31.3 vs. 17.8±23.1; P=0.010). IBD prevalence at baseline was higher in the very D2T group (41.7 vs. 3.1%; P<0.001). None of the very D2T patients presented a fibromyalgia.

CONCLUSION

D2T axSpA was associated with higher disease activity, peripheral involvement, extra-musculoskeletal manifestations and fibromyalgia. Very D2T patients represented a minim proportion of patients after applying a more stringent definition including a temporal criterion of 2 years and might be independent from fibromyalgia.