Prevalence of ankylosing spondylitis in Spain: EPISER2016 Study.

Objective: The aim of this study was to estimate the prevalence of ankylosing spondylitis (AS) in Spain. Method: This is a cross-sectional, population-based study of people aged 20 years or older in Spain. Randomly selected individuals were contacted by telephone and rheumatic disease screening was performed. If the first screening was positive, medical records were then reviewed and/or a telephone questionnaire was conducted by a rheumatologist, followed by an appointment if necessary. Cases had to fulfil the modified New York (mNY) criteria. Results: In total, 4916 individuals were included, of whom 355 had a positive screening result for AS. Of these, 11 were classified as AS. An additional individual who reported a prior diagnosis of rheumatoid arthritis had a diagnosis of AS confirmed on review of the medical records. Estimated prevalence was 0.26% (95% CI 0.14-0.49). Conclusion: EPISER2016 is the first population-based study to estimate the prevalence of AS in Spain, which has been estimated as being similar to that in other European countries.