Assessing Disease Activity and Disability
The ankylosing spondylitis disease activity score (ASDAS) is calculated using an online calculator [21,22] ( https://www.asas-group.org/ instruments/asdas-calculator ). Based on specific cut points, disease activity can be classified into inactive disease, low, high or very high disease activity (Table 2). The ASDAS cutoff for clinically important improvement between examinations
The ankylosing spondylitis disease activity score (ASDAS) is calculated using an online calculator[21,22] (https://www.asas-group.org/ instruments/asdas-calculator). Based on specific cut points, disease activity can be classified into inactive disease, low, high or very high disease activity (Table 2). The ASDAS cutoff for clinically important improvement between examinations is ≥1.1, and the cutoff for a major improvement is ≥2.0. An alternative to the ASDAS is the Bath ankylosing spondylitis disease activity index (BASDAI),[23] with a score ≥4/10 considered ‘active’ disease, with a change of ≥50% in the BASDAI reflecting a clinically relevant improvement.[24] The Bath ankylosing spondylitis functional index (BASFI) measures functional disability in 10 different areas based on a visual analogue scale of 0 - 10.[25]
| Table 2. Disease activity assessment tools and cutpoints for axial spondyloarthritis | ||
| Cutpoint | Ankylosing spondylitis disease activity score (ASDAS) | Bath ankylosing spondylitis disease activity index (BASDAI) |
| Inactive disease | <1.3 | <1.6 |
| Low disease activity | <2.1 | <2.9 |
| High disease activity | <3.5 | <3.8 |
| Very high disease activity | ≥3.5 | ≥3.8 |
| Online calculator | https://www.asas-group.org/instruments/asdas-calculator | |
Maharaj, A. B., et al. (2024). South African Rheumatism and Arthritis Association 2024 guidelines for the management of axial spondyloarthritis. South African Medical Journal, 114(10), e2668.