Across the board, baseline measures of disease activity were lower in patients who met the fibromyalgia criteria versus those who did not. This included the BASDAI and the Bath Ankylosing Spondylitis Functional Index, where scores were approximately 6.5 and 4.5 for each measure.
“Quality of life was significantly lower in those who were fibromyalgia positive,” Dr. Macfarlane said. Indeed, whatever the measure used, from the disease-specific Ankylosing Spondylitis Quality of Life (ASQoL) Scale to the general EuroQoL Quality of Life Scale, there were significant differences between those who did and did not meet fibromyalgia criteria. There were also higher scores for depression, anxiety, poorer-quality sleep, and higher levels of fatigue.
Patients treated with TNFi therapy showed improvement in both BASDAI and ASQoL scores regardless of whether they met fibromyalgia criteria, but crucially, the responses were still lower and significantly different from those without fibromyalgia.
An ASAS20 response to TNFi therapy was met by “slightly fewer” patients who met the fibromyalgia criteria than by those who did not at all follow-up points: at 3 months (about 35% vs. 45%), 6 months (about 58% vs. 61%), and 12 months (about 60% vs. 62%).
A high score on the Symptom Severity Scale but not the Widespread Pain Index of the fibromyalgia criteria was associated with a lower response to TNFi therapy at 3 months. “Such patients may benefit from the use of TNFi and nonpharmacological therapy,” Dr. Macfarlane said.