A spectrum of disease extends beyond the rigid confines of ankylosing spondylitis (AS). Axial spondyloarthritis (axSpA) encompasses non-radiographic axSpA (nr-axSpA) in individuals without established radiographic changes but with other clinical/imaging axSpA features and AS in those with definite sacroiliac joint changes on pelvic X-rays. A broad consensus about the management of nr-axSpA is emerging among clinicians, but the evidence base remains open to question. To explore whether nr-axSpA and AS should be treated similarly, we examined the literature on their prevalence, natural history, disease burden, and treatment. There is strong evidence that nr-axSpA and AS are expressions of the same disease. Approximately 10% of patients with nr-axSpA will develop radiographic disease over 2 years; after >20 years, the figure may exceed 80%. Nr-axSpA patients have lower CRP and less spinal inflammation on MRI than AS patients but similar disease activity, pain, and quality-of-life impairment. Most patients with nr-axSpA manage well with conservative treatment, but a minority has severe disabling symptoms. Anti-TNF therapy has demonstrated similar efficacy and safety in nr-axSpA and AS. Current evidence does not clearly indicate that anti-TNF treatment can inhibit or limit bony progression of AS, the basis of conservative and anti-TNF treatment is control of symptoms and function. For some patients with nr-axSpA, the need for powerful treatments is as great as in some with AS; thus, treatment of axSpA should be consistent across the axSpA spectrum with anti-TNF agents being available, irrespective of radiographic change, according to the same criteria as those applied to AS.
Keywords: Ankylosing spondylitis; Axial spondyloarthritis; Burden of illness; Epidemiology; Non-steroidal anti-inflammatory drugs; Tumour necrosis factor.