Abstract
Objective The diagnosis of axial spondyloarthritis (axSpA) is hampered by diagnostic delay. Computed Tomography (CT) undertaken for non-musculoskeletal (MSK) indications in patients with inflammatory bowel disease (IBD) offers an opportunity to identify sacroiliitis for prompt rheumatology referral. The study aims to identify what proportion of IBD patients who underwent abdominopelvic CT for non-MSK indications have axSpA and explore the role of a standardised screening tool to prospectively identify axSpA on imaging.
Methods Abdominopelvic CT scans of verified IBD patients, age range 18-55, performed for non-MSK indications were reviewed by radiology for presence of CT-defined sacroiliitis (CTSI, using criteria from a validated CT screening tool). All patients identified were sent a screening questionnaire and those with self-reported chronic back pain (CBP), duration > 3 months, onset < 45 years were invited for rheumatology review.
Results CTSI was identified in 60 of 301 patients. Thirty-two (53%) responded to the invitation to participate and 27 were enrolled. Of these, eight had a pre-existing axSpA diagnosis and five did not report CBP. Fourteen patients underwent rheumatology assessment; three of 14 (21.4% [95% CI: 4.7%, 50.8%]) had undiagnosed axSpA. In total, 11 of 27 (40.7% [95% CI: 22.4%, 61.2%]) patients had a rheumatologist verified diagnosis of axSpA.
Conclusion At least 5.0% of IBD patients (3/60) undergoing abdominopelvic CT for non-MSK indications with CTSI have undiagnosed axSpA, and overall, 18.3% (11/60) have axSpA. This reveals a significant hidden population of axSpA and highlights the need for a streamlined pathway from sacroiliitis detection to rheumatology referral.
