Fibromyalgia adversely affects TNF inhibitor response in axSpA patients
The coexistence of fibromyalgia in patients with axial spondyloarthritis (axSpA) exerts a negative effect on response to tumour necrosis factor blocker (TNFb), according to a study. This effect appears to be associated with the self-reported instruments used in fibromyalgia evaluation rather than a different treatment effect of the agent in this population.
The prospective study included 508 axSpA patients (mean age 41.4 years; 46.7 percent female) initiating a TNFb. Fibromyalgia was defined by a score ≥5/6 on the Fibromyalgia Rapid Screening Tool (FiRST) questionnaire and by a sustained positive FiRST at the effectiveness visit (12 weeks of TNFb treatment), as well as by a fulfilment of the 1990 American College of Rheumatology criteria.
Of the patients, 192 (37.8 percent) were identified to have fibromyalgia. Patients with fibromyalgia were more likely to be female (55.7 vs 41.1 percent) and to have peripheral enthesitis (64.7 vs 47.8 percent) and less likely to have a university degree (34.6 vs 51.6 percent).
The primary efficacy endpoint of the proportion of patients achieving a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI 50) at the effectiveness visit was lower among patients with fibromyalgia than among those without the condition (45.3 vs 54.1 percent).
The group of axSpA patients with fibromyalgia also had a lower percentage of success at 12 weeks of treatment for most of the effectiveness endpoints—Assessment in SpondyloArthritis international Society [ASAS] 40, ASAS 20, Ankylosing Spondylitis Disease Activity Score [ASDAS] moderate disease activity, ASDAS inactive disease and NSAID score ≥50 percent, among others—with the exception of the C reactive protein change endpoints, which were not significantly different between the fibromyalgia and nonfibromyalgia subgroups.
The present data confirm that concomitant fibromyalgia is more frequent in patients with axSpA than in the general population but not more frequent than in other chronic rheumatic diseases, researchers said. [Pain Res Treat 2012;2012:1–8; Rheumatol Int 2014;34:1275–80; Clin Exp Rheumatol 2017;35(Suppl 105):35–42]
Additionally, the findings highlight the significance of evaluating the presence of coexisting fibromyalgia in patients with axSpA when evaluating treatment response, but also when determining treatment targets, researchers noted.
“Further studies should be conducted to confirm these results and to evaluate the relevance of the implementation of the FiRST questionnaire in daily practice,” they added.