Table 3.

Disease activity and patient-reported outcome measures commonly used by rheumatologists for patients with axSpA

Disease Activity Measure	Assessment	Format	Interpretation
Single-item questionnaires	• PGA • Spinal pain	VAS or NRS (scale of 0–10)	• < 50% improvement in pain after treatment indicates active disease • PGA or pain score > 4 indicates active disease
BASDAI	Back pain, fatigue, peripheral joint pain and swelling, localized tenderness, severity and duration of morning stiffness scored using a 10-cm VAS	The BASDAI score (scale of 0–10) is the overall mean of individual scores from a 6-item questionnaire	• A score of ≥ 4 indicates active disease • Other common endpoints: ≥ 50% improvement from baseline (BASDAI50); achievement of MCID
ASDAS	Back pain, duration of morning stiffness, PGA, peripheral joint pain and swelling, and CRP (or rarely ESR)	ASDAS is a composite score (scale of 0–10) calculated from PROs and CRP measurement	• A score of < 1.3 indicates inactive disease • A change of ≥ 1.1 from baseline is considered a clinically important improvement • Other common endpoints: low disease, < 2.1; high disease, ≥ 2.1 to ≤ 3.5; very high disease, > 3.5
RAPID3	Pain, functional impairment, and PGA	The RAPID3 score (scale of 0–10) is calculated as the weighted sum of the individual PROs	• A score of ≥ 3.33 indicates active disease

ASDAS, Ankylosing Spondylitis Disease Activity Score; axSpA, axial spondyloarthritis; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; MCID, minimum clinically important difference; NRS, numeric rating scale; PGA, patient global assessment; RAPID3, Routine Assessment of Patient Index Data 3; VAS, visual analog scale