About the BASDAI Score
The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) is a validated, self-reported questionnaire that summarises how active axial spondyloarthritis has felt over the past week. You rate six symptoms on a 0-10 scale, and the calculator combines them into a single score from 0 (no activity) to 10 (very severe) so you can track change over time and share a consistent number with your rheumatologist.
How the score is calculated
The six questions cover: (1) overall fatigue, (2) spinal pain in the neck, back or hip, (3) pain or swelling in other joints, (4) discomfort from areas tender to touch or pressure (enthesitis), (5) the severity of morning stiffness, and (6) how long morning stiffness lasts. Questions 5 and 6 both describe morning stiffness, so they are averaged and count together as a single item:
- Add questions 1-4 — each 0-10, giving a subtotal from 0 to 40.
- Average questions 5 and 6 — (Q5 + Q6) / 2, a value from 0 to 10.
- Combine and divide by 5 — BASDAI = (Q1 + Q2 + Q3 + Q4 + (Q5 + Q6) / 2) / 5.
Because the two stiffness questions are averaged first, the final score stays on the same 0-10 scale as each individual answer. Question 6 is anchored so that 0 means no morning stiffness and 10 means stiffness lasting two hours or more; scores refer to how you have felt over the last week.
Interpreting your result
A BASDAI of 4 or higher is the commonly used cut-off for active, suboptimally controlled disease, and it often forms part of the criteria for starting or escalating biologic therapy. Scores below 4 point to lower disease activity. The number is most useful when tracked over weeks and months: a rising trend can signal a flare, while a falling trend suggests treatment is helping.
When to consult a professional
BASDAI reflects your symptoms only; it is not a diagnosis and does not replace clinical assessment, imaging, or blood tests. Discuss your score, and any change in it, with a licensed rheumatologist before making decisions about medication or treatment.