Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)

The BASDAI is a patient-reported outcome measure of disease activity in ankylosing spondylitis (AS), a chronic inflammatory arthropathy affecting the spine and axial skeleton. Introduced by Garrett et al. in 1994, BASDAI uses six simple patient self-report items focused on the cardinal symptoms of AS: fatigue, spinal pain, peripheral joint involvement, and morning stiffness. As a PRO measure, BASDAI is practical for routine monitoring, responsive to treatment, and strongly associated with clinical outcomes and spinal damage progression, making it a cornerstone outcome in AS management and clinical trials.