Objective: To develop a reproducible and simple radiologic scoring system for the spine in patients with ankylosing spondylitis (AS): the Bath Ankylosing Spondylitis Radiology Index for the spine (BASRI-s).
Methods: Radiographs of 470 patients with AS were scored using the New York criteria for the sacroiliac joints and, similarly, grading the lumbar and cervical spine on a scale of 0-4 (for normal, suspicious, mild, moderate, and severe). These 3 scores were added together to produce the BASRI-s score (scored 2-12). Radiographs of 188 patients were used to test reproducibility. Blinded radiographs of 89 non-AS patients were included, randomly, to assess disease specificity. Sensitivity to change was assessed using 177 radiographs from 58 AS patients.
Results: Intra- and interobserver variation showed 75-86% and 73-79% complete agreement at all sites, respectively. Specificities of 0.83-0.89 suggested that the lumbar and cervical spine BASRI scores were disease specific. Sensitivity to change became apparent at 2 years (P < 0.001). Using a lateral view and an anteroposterior view of the lumbar spine was more sensitive than using a lateral view alone. Grading a set of radiographs (sacroiliac joints, lumbar spine, and cervical spine) took 30 seconds.
Conclusion: BASRI is a reliable method for grading radiographic changes in patients with AS. It is disease specific, sensitive to change, valid, simple, and rapid to perform.