The changing states of fibromyalgia in patients with axial spondyloarthritis: results from the British Society of Rheumatology Biologics Register for Ankylosing Spondylitis.

High levels of disease activity and the presence of widespread pain is associated with the development of FM in patients with axSpA, while low levels of the same variables and starting a TNF inhibitor are associated with recovery from FM. The presence of comorbid FM should be considered in patients with persistent high axSpA disease activity and widespread pain.