Ankylosing Spondylitis: Investigation and Management

Key points

• Ankylosing spondylitis: an HLA-B27-associated spondyloarthropathy, typically presenting in men (about 3:1) aged 20-30 with inflammatory back pain (worse in the morning, better with exercise).
• HLA-B27 is positive in about 90% of patients but also in 8-10% of the general population, so it is supportive, not diagnostic.
• Plain X-ray of the sacroiliac joints is the key investigation: sacroiliitis (subchondral erosions, sclerosis), squaring of vertebrae, syndesmophytes and 'bamboo spine'. MRI shows early sacroiliitis before X-ray changes.
• Management: regular NSAIDs plus physiotherapy and exercise are first-line; sulfasalazine only helps peripheral (not axial) disease.
• For active disease despite NSAIDs: a TNF inhibitor (adalimumab, etanercept, infliximab, golimumab, certolizumab), an IL-17 inhibitor (secukinumab, ixekizumab), or the JAK inhibitor upadacitinib. Screen for extra-articular features (anterior uveitis, aortic regurgitation, apical lung fibrosis, IBD).
• MHRA (April 2023) JAK inhibitor safety: use a JAK inhibitor only if there is no suitable alternative in people aged 65 or over, current or past long-term smokers, or those with other risk factors for cardiovascular disease or malignancy · use with caution if there are other VTE risk factors · carry out periodic skin examinations.