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BASDAI Calculator (Bath Ankylosing Spondylitis Disease Activity Index)

Calculate the BASDAI for ankylosing spondylitis and axial spondyloarthritis from six 0–10 questions on fatigue, spinal pain, joint swelling, tenderness and morning stiffness — 4 or more means active disease.

1. Fatigue or tiredness (last week)

2. Neck, back or hip pain from the condition

3. Pain or swelling in other joints

4. Discomfort from areas tender to touch or pressure

5. Severity of morning stiffness after waking

6. Duration of morning stiffness

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How it works

BASDAI = [Q1 + Q2 + Q3 + Q4 + (Q5 + Q6) / 2] / 5, each question rated 0–10 (Q6 duration: 0 h = 0, 1 h = 5, ≥ 2 h = 10). Range 0–10; ≥ 4 suggests active disease.

The Bath Ankylosing Spondylitis Disease Activity Index (Garrett et al., Journal of Rheumatology 1994) is a self-reported measure of disease activity over the past week in ankylosing spondylitis and axial spondyloarthritis. The two morning-stiffness questions are averaged so stiffness carries the same weight as each other domain. A BASDAI of 4 or more is the classic threshold for active disease used, together with the clinician’s opinion, when considering biologic therapy, and a fall of 50% or 2 units is a common response target.

Worked example

Ratings of fatigue 6, spinal pain 5, other joints 3, tenderness 4, stiffness severity 6 and stiffness lasting 60 minutes (5 on the scale): BASDAI = [6 + 5 + 3 + 4 + (6 + 5) / 2] / 5 = 23.5 / 5 = 4.7 — active disease (≥ 4).

Sources: Garrett S et al. A new approach to defining disease status in ankylosing spondylitis: the BASDAI. J Rheumatol 1994

Frequently asked questions

What is a good BASDAI score?

Lower is better. Below 4 is usually considered controlled or inactive disease; 4 or more suggests active disease that may need a treatment change.

How is morning stiffness duration scored?

On a 0–10 line where 0 is none, 5 is one hour and 10 is two hours or more. Enter the minutes and the calculator converts them (minutes ÷ 12, capped at 10).

What change in BASDAI counts as a response?

A fall of at least 50% or at least 2 points on the 0–10 scale is widely used to judge response to biologic therapy after 12–16 weeks.

BASDAI or ASDAS — which should I use?

ASDAS adds a blood marker (CRP or ESR) and is preferred by ASAS for defining disease activity states; BASDAI is purely patient-reported and is still widely used in guidelines.

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Clinical decision tool for education and for use by trained clinicians alongside clinical judgement — not a diagnosis and not a substitute for medical assessment. Scores validated in specific populations may not apply to every patient.