There is broad disagreement about the appearance of sacroillitis in diagnostic imaging, raising questions about current diagnostic criteria.
Van den Berg R, Lenczner G, Feydy A, et al. Agreement between clinical practice and trained central reading in reading of sacroiliac joints on plain pelvic radiographs. Results from the DESIR Cohort. Arthritis Rheumatol. (2014) 66:2403-2411.
The diagnosis of ankylosing spondylitis (AS) is determined by the presence or absence of sacroiliitis on plain radiographs of the sacroiliac (SI) joints. Unfortunately, both trained central readers and local rheumatologist/radiologists regularly failed to agree on the recognition of radiographic sacroiliitis, according to the results of a new study.
In fact, local rheumatologists/radiologists often falsely diagnosed AS, leading the researchers to conclude that “the role of radiographic sacroiliitis as a diagnostic criterion for axial spondyloarthritis should be reevaluated.”
The researchers analyzed data from 688 patients aged 18 to 50 years from 25 centers in France who presented with inflammatory pack pain (IBP) and symptoms suggesting axial spondyloarthritis (SpA). A local rheumatologist/radiologist and two central trained readers scored baseline radiographs of the SI joints. A third reader was used in cases where the two central readers disagreed.
The two central readers had only moderate agreement when identifying the presence or absence of sacroiliitis. About 15% of the images needed review by the third reader.
Discrepancies were even greater comparing the central with the local reviewers. Local reviewers judged 26.6% of patients as having radiographic sacroiliitis, compared to only 21.1% in the judgment of the central readers.
Almost half of the patients identified as having positive findings on the radiographs by local review were identified as negative by central review.