Evaluation of whether extremely high enthesitis or Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores suggest fibromyalgia and confound the anti-TNF response in early non-radiographic axial spondyloarthritis.

OBJECTIVES: Differentiating between pain from spondyloarthritis (SpA) and pain from fibromyalgia is challenging. We evaluated patients with non-radiographic axial SpA (nr-axSpA) to determine the percentage of patients with extremely high enthesitis and/or Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores, the relationship between extreme scores and depression, and the effect of extreme scores on treatment outcomes with etanercept.

METHODS: Patients with nr-axSpA received double-blind etanercept 50 mg or placebo weekly and were divided into those who did vs did not have extreme scores at baseline. Extreme scores were defined as the highest quintile for enthesitis score (≥6), and/or scores ≥8 on three of five BASDAI items (excluding morning stiffness duration). Depression was assessed with the Hospital Anxiety and Depression Scale, depression subscale (HADS-D) and medication use. Week 12 outcomes included Assessment of SpondyloArthritis (ASAS) 40 and ASAS partial remission.

RESULTS: At baseline, 35/213 (16.4%) patients met extreme enthesitis criteria, 31 (14.6%) met extreme BASDAI criteria, 12 (5.6%) met both, and 135 (63.4%) met neither. More patients with extreme scores than without met the HADS-D definition of depression: 35/68 (51.5%) vs. 27/118 (22.9%), p<0.0001. For patients with vs. without extreme scores who received etanercept, no significant difference existed in week 12 ASAS 40: 13/41 (31.7%) vs. 21/60 (35.0%), respectively, or ASAS partial remission: 8/41 (19.5%) vs. 19/60 (31.7%).

CONCLUSIONS: Extreme enthesitis and/or BASDAI scores were associated with measurements of depression, but did not affect week 12 ASAS 40 or ASAS partial remission.