Repeat imaging of sacroiliac joints not useful in diagnostic workup of axSpA
The usefulness of repeating magnetic resonance imaging (MRI) of the sacroiliac joints (MRI-SI) after 3 months or 1 year in the diagnostic workup of chronic back pain patients suspected of axial spondyloarthritis (axSpA) appears to be limited, according to data from the SPACE cohort. Specifically, only a small percentage of patients exhibit changes in MRI-SI status.
A total of 188 patients with chronic back pain (mean age 31.0 years; 38.3 percent male; symptom duration, 13.2 months) underwent evaluation of all SpA‐features and repeated MRI‐SI at baseline, 3 months and 1 year. Thirty-one patients (16.5 percent) were MRI‐SI‐positive at baseline. MRI‐SI positivity was evaluated according to Assessment of SpondyloArthritis International Society (ASAS).
MRI-SI status changed from positive to negative in 3/27 patients (11.1 percent) after 3 months and in 11/29 patients (37.9 percent) after 1 year. This change was partly induced by antitumour necrosis factor therapy initiation.
On the other hand, status changed from negative to positive in 5/116 patients (4.3 percent) after 3 months and in 10/138 patients (7.2 percent) after 1 year.
On generalized estimating equation analysis, HLA‐B27‐positivity and male gender emerged as independent determinants of a positive MRI-SI at any time point (42 percent in HLA‐B27-positive males; 6 percent in HLA‐B27-negative females).
Meanwhile, MRI-SI status at baseline strongly predicted MRI-SI status at follow-up, such that a negative status at baseline predicted a very low likelihood of a positive MRI during follow‐up (max, 7 percent).
The present data suggest that the usefulness of repeating a negative MRI in terms of diagnostic yield is low, although there are different risks related to sex and HLA-B27 status, researchers said.