How to stage ankylosing spondylitis Ankylosing spondylitis (AS) is a chronic systemic connective tissue disease of unknown origin, involving mainly the sacroiliac, hip, intervertebral and cribriform joints. There are three clinical stages i.e. early, progressive and stable. Most scholars have staged the disease according to the degree of damage to the sacroiliac joint. Meng Jiaxiao et al. classified the CT manifestations of sacroiliac arthritis in AS patients into 0 – IV with reference to the New York criteria, and considered that early stage corresponds to CT grade I-II, clinically progressive stage corresponds to CT grade III, and clinically advanced stage corresponds to CT grade IV. BASRI was reported by MacKay, Calin, etc., and then endorsed by the ASAS working group, and is a radiological scoring standard for AS that is now widely used internationally. It evaluates the cervical spine, lumbar cone, sacroiliac joint, and hip separately, and is currently the only standard for grading the hip, but not the thoracic spine, and it has a total score range of 2 to 16.