The Ankylosing Spondylitis Performance Index: Reliability and Feasibility of an Objective Test for Physical Functioning.

Objective: Physical function in patients with axial spondyloarthritis (axSpA) is currently evaluated through questionnaires. The Ankylosing Spondylitis Performance Index (ASPI) is a performance-based measure for physical functioning, which has been validated in Dutch patients with radiographic (r-) axSpA. The interrater reliability has not yet been determined.