CONCISE REPORT Assessment of outcome in ankylosing spondylitis: an extended radiographic scoring system

Objective: To develop and validate an extensive radio-graphic scoring system for ankylosing spondylitis (AS). Methods: The Stoke Ankylosing Spondylitis Spinal Score (SASSS) was modified by adding a score for the cervical spine and defining squaring. This modified SASSS (mSASSS) is the sum of the lumbar and cervical spine score (range 0– 72). 370 lateral views of the lumbar and cervical spine were used for development of the mSASSS, standardisation of observers, and for studying reliability. In a 48 week NSAID study of 57 patients, change over time and construct validity were studied. Results: Interobserver correlations of the lumbar and cervical spine scores were good (r.0.95). The interobserver duplicate error was 0.55 in a range from 0 to 36. The mean change in the cervical and lumbar spine score