🦴 BASDAI Ankylosing Spondylitis Activity Index
The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) is a patient-reported measure of axial spondyloarthritis activity scored 0–10.
The two morning-stiffness items (severity and duration) are averaged before being combined, so they together carry the weight of a single item (original synthesis · not guideline verbatim).
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When to use
Enter the six 0–10 items (fatigue, spinal pain, peripheral joint pain/swelling, enthesitis, morning-stiffness severity, morning-stiffness duration) over the past week; the tool returns the index.
How it works
BASDAI = (Q1 + Q2 + Q3 + Q4 + (Q5 + Q6)/2) / 5. A value ≥4 generally indicates active disease.
Key points
- The two morning-stiffness items (severity and duration) are averaged before being combined, so they together carry the weight of a single item (original synthesis · not guideline verbatim).
- A BASDAI ≥4 is a common threshold for active disease and is often part of the assessment before starting or escalating a biologic.
- It is increasingly paired with or replaced by ASDAS, which incorporates CRP and better reflects objective inflammation.
References
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| ① Fatigue/tiredness level | 0 0–10 |
|---|---|
| ② Neck/back/hip pain | 0 0–10 |
| ③ Peripheral joint pain/swelling | 0 0–10 |
| ④ Discomfort on touch/pressure (enthesitis) | 0 0–10 |
| ⑤ Morning stiffness severity | 0 0–10 |
| ⑥ Morning stiffness duration | 0 0–10 |
→BASDAI0/10
- Interpretation threshold：≥4 active
Frequently asked questions
- What is BASDAI Ankylosing Spondylitis Activity Index?
- The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) is a patient-reported measure of axial spondyloarthritis activity scored 0–10.
- How is BASDAI Ankylosing Spondylitis Activity Index calculated? What is the core formula?
- BASDAI = (Q1 + Q2 + Q3 + Q4 + (Q5 + Q6)/2) / 5. A value ≥4 generally indicates active disease.
- When is BASDAI Ankylosing Spondylitis Activity Index used?
- Enter the six 0–10 items (fatigue, spinal pain, peripheral joint pain/swelling, enthesitis, morning-stiffness severity, morning-stiffness duration) over the past week; the tool returns the index.
- What are the key clinical points for BASDAI Ankylosing Spondylitis Activity Index?
- The two morning-stiffness items (severity and duration) are averaged before being combined, so they together carry the weight of a single item (original synthesis · not guideline verbatim). A BASDAI ≥4 is a common threshold for active disease and is often part of the assessment before starting or escalating a biologic. It is increasingly paired with or replaced by ASDAS, which incorporates CRP and better reflects objective inflammation.
- What are the limits and cautions when using BASDAI Ankylosing Spondylitis Activity Index?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is BASDAI Ankylosing Spondylitis Activity Index calculated in practice? Can you show a worked example?
- Inputs: ① Fatigue/tiredness level 0 0–10, ② Neck/back/hip pain 0 0–10, ③ Peripheral joint pain/swelling 0 0–10, ④ Discomfort on touch/pressure (enthesitis) 0 0–10, ⑤ Morning stiffness severity 0 0–10, ⑥ Morning stiffness duration 0 0–10 → Result: BASDAI 0 /10（Interpretation threshold: ≥4 active）