Early referral recommendations for ankylosing spondylitis (including pre-radiographic and radiographic forms) in primary care.

An earlier diagnosis of ankylosing spondylitis (AS) is required because there is still a 5-7 year delay between first symptoms and diagnosis, and new effective treatments are available for active disease. Primary care physicians need easy to apply parameters to help them identify patients with suspected AS for onward referral. The best measures found were inflammatory back pain and HLA-B27 positivity.