Bath Ankylosing Spondylitis Functional Index (BASFI)

The BASFI is a patient-reported outcome measure of functional disability in ankylosing spondylitis (AS), assessing physical limitations in 10 common daily activities. Introduced by Calin et al. in 1994, BASFI measures the impact of AS on quality of life and functional capacity, complementing BASDAI (disease activity). While BASDAI reflects inflammatory burden, BASFI reflects the consequences of inflammation and spinal damage on a patient's ability to perform daily tasks. BASFI is used alongside BASDAI in AS management to capture both disease activity and its functional impact.