With respect to MRI, Dr. Deodhar pointed out that bone marrow edema at the sacroiliac joints can be seen in many healthy individuals and should not be used to diagnose spondyloarthritis without taking into account the entire clinical picture.
Weber et al. conducted a study in which MRI scans (T1‐weighted and short tau inversion recovery [STIR] sequences) of the sacroiliac joints were obtained from 187 subjects, including patients with non-specific back pain and healthy controls.3 Bone marrow edema, erosions and fat infiltration were observed in up to 27% of control subjects with non-specific back pain and in 24% of health controls.
Although it is possible that some of these patients may have clinically asymptomatic, atypical or early spondyloarthritis, the authors point out that the presence of low-grade, acute lesions of the sacroiliac joints may be due to mechanically induced signal alterations or degenerative changes, and, thus, care should be taken not to misclassify some young patients with back pain as having spondyloarthritis. The authors note that erosions were much less frequently observed in both control groups when compared with bone marrow edema and fat infiltration. Thus, erosive findings may be more specific for true spondyloarthritis.3
Treatment Recommendations
Dr. Deodhar also discussed the 2019 update of the ACR/Spondylitis Association of America/Spondyloarthritis Research and Treatment Network recommendations for the treatment of ankylosing spondylitis and nr-axSpA.4 He noted that, in these guidelines, treatment recommendations for ankylosing spondylitis and nr-axSpA are similar.
Tumor necrosis factor (TNF) inhibitors remain recommended as the first-line biologic treatment for these patients and are recommended over interleukin-17 (IL-17) inhibitors, mostly because a more robust response is achieved using TNF inhibitor treatment and because TNF inhibitors treat many of the extra-articular manifestations of disease, such as uveitis. However, in patients who have had a primary nonresponse to TNF inhibitors, IL-17 inhibitors are recommended over trying a second TNF inhibitor.
TNF and IL-17 inhibitors are both recommended over using tofacitinib in patients with ankylosing spondylitis and nr-axSpA. Sulfasalazine was included in the guidelines as a treatment only for persistent peripheral arthritis and not for treatment of axial involvement.
Although routine monitoring of C-reactive protein is indicated for all patients, this is not the case for routine monitoring with MRI or radiographs of the spine or sacroiliac joints.
In addition, screening for osteoporosis with bone density scans is recommended for these patients.
Regarding items that are not advisable, the authors state that co-administration of low-dose methotrexate with a TNF inhibitor is not recommended. Discontinuation or tapering of biologics in patients with stable disease is also not recommended.4