[Early diagnosis of ankylosing spondylitis and spondyolarthritis and predictors of outome].

Ankylosing spondylitis (AS) is a relevant differential diagnosis in patients with chronic back pain. Inflammatory back pain is the leading symptom in AS and also in undifferentiated spondyloarthritis. The diagnosis of AS is often delayed by 5 to 10 years, mainly because radiographs do not reveal definite radiographic sacroiliitis during the initial stage of the disease. Diagnostic algorithms based on Bayesian models have been developed to facilitate making an early diagnosis in daily practice. Moreover, screening parameters for early referral to the rheumatologist of patients seen in primary care have been evaluated. Male sex, extraspinal manifestations, and existing syndesmophytes on radiographs appear to be predictors of a worse disease outcome.