Axial spondyloarthritis

The prevalence of axial spondyloarthritis (AxSpA) is approximately 1% of the general population. Ankylosing spondylitis (AS) affects 0.2–0.5% of the northern European population, the prevalence varying with the prevalence of HLA-B27. AS affects men three times more often than women, but AxSpA (without X-ray changes) affects men and women equally. Symptoms usually begin in the third decade of life with inflammatory back pain. The key pathological element is enthesitis, though the main diagnostic feature is sacroiliitis. Approximately one-third of patients develop peripheral lesions including lower limb oligoarthritis, heel enthesitis, iritis, inflammatory bowel disease and psoriasis. Vertebral osteoporosis is not uncommon and cardiovascular disease and renal impairment may complicate severe AS. The diagnosis of AxSpA can be made on the basis of imaging (X-ray or MRI) or on clinical features alone.The cause(s) of AS remain unknown. Genetic factors, including HLA-B27 and the interleukin-23 receptor, confer susceptibility to AS but environmental precipitating factors have not been identified. Treatment involves the maintenance of spinal movement and comfort through exercise supported, where necessary, by analgesia and anti-inflammatory treatment. Disease-modifying anti-rheumatoid drugs are not effective for spinal disease, but TNF-α inhibitor drugs provide dramatic improvements in symptoms, function and quality of life.