Important insights into development and recovery from fibromyalgia and how comorbidities influence patient response to TNF inhibitors have been obtained from a UK registry of ankylosing spondylitis (axSpA) patients.
A prospective study of 800 participants from the British Society of Rheumatology Biologics Register for Ankylosing Spondylitis assessed whether patients met the criteria for fibromyalgia at baseline and two or three follow up appointments.
Researchers found that 115 met the criteria for fibromyalgia at the start of the study but 70% of them had recovered at follow up around 10 months later.
Of the 686 who didn’t have fibromyalgia at baseline, 45 went on to develop it, the researchers reported in Rheumatology.
Further analysis showed that high levels of axSpA disease activity and widespread pain was associated with future fibromyalgia development, while low disease activity was associated with recovery from it.
Comorbidities and TNFi response
A second study also making use of the register analysed data on almost 1,000 patients starting their first TNF inhibitor. It found higher disease severity at baseline and throughout among those with comorbidities, and that patients with multiple other conditions had poorer treatment outcomes.
The research team found that axSpA patients with two or more comorbidities had significantly lower absolute improvements in function and health-related quality of life in response to their first TNF inhibitor.
Patients also had a significantly higher rate of treatment discontinuation than those without comorbidities who were started on the drugs. This went up to more than double the rate of discontinuation in those with three or more other health conditions.
“Taken together, [the] results can be used to better inform clinicians and educate patients about the likelihood of response to the first TNFi given baseline comorbidity status,” the study authors concluded.
“Further research is needed to identify potentially modifiable comorbidities that may improve response.”
When looking at development and recovery from fibromyalgia, the researchers pointed out that identifying and untangling those symptoms from axSpA itself was complex.
“The clinician should keep in mind that an unexpectedly high axSpA disease activity might have captured [fibromyalgia] disease activity and that disentangling the two is necessary in order to target the therapy, while also considering the possibility of misdiagnosis.
“The knowledge that 50% of patients who fulfilled the [criteria] at baseline did not fulfil the criteria after two years may give hope to patients suffering from [fibromyalgia],” they advised.
The study results were also published in the Rheumatology.