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Suspected axial spondyloarthritis — SCE Rheumatology MCQ

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ModerateSpondyloarthropathiesSuspected axial spondyloarthritisSCE Rheumatology

A 24-year-old woman has had inflammatory lower back pain for 8 months. She has a first-degree relative with ankylosing spondylitis. Examination demonstrates reduced lumbar flexion and pain on sacroiliac joint provocation. Her CRP is 18 mg/L. A plain radiograph of the sacroiliac joints does not show sacroiliitis meeting modified New York criteria. What is the most appropriate next investigation?

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Correct answer: E — Unenhanced MRI using an inflammatory back pain protocol

The correct answer is E. She has a high clinical probability of axial spondyloarthritis: young age, chronic inflammatory back pain, a first-degree family history, abnormal sacroiliac provocation and raised CRP. NICE recommends unenhanced MRI using an inflammatory back pain protocol when sacroiliac joint radiographs do not demonstrate sacroiliitis meeting modified New York criteria. This can identify active inflammatory lesions consistent with non-radiographic axial spondyloarthritis. CT demonstrates structural bone damage but is less suitable for detecting active early inflammation and entails ionising radiation. Ultrasound cannot adequately assess the deep sacroiliac joint surfaces. Bone scintigraphy is not recommended because of poor diagnostic performance. Delaying investigation to repeat radiography risks missing early disease and prolonging diagnostic delay.

Reference: National Institute for Health and Care Excellence. NG65: Spondyloarthritis in over 16s—diagnosis and management, recommendations 1.2.4–1.2.10. 2017. https://www.nice.org.uk/guidance/ng65/chapter/Recommendations