BASDAI: The validated standard for assessing disease activity in patients with Axial Spondyloarthritis.
Rate Your Symptoms
Rate each of the 6 questions from 0 to 10 to calculate your BASDAI score.
Guidelines & Evidence
Verified
Last Review: 2026-07-17
When to Use
When to Use
Monitoring disease activity in ankylosing spondylitis and axial spondyloarthritis
Guiding treat-to-target decisions and biologic therapy eligibility
Serial tracking of treatment response over time
Clinical trial endpoint for axSpA therapeutics
Screening for active disease requiring therapy escalation
Patient Population
Adults with confirmed ankylosing spondylitis by modified New York criteria or axial spondyloarthritis by ASAS criteria. Validated across disease durations and used internationally in both clinical practice and research.
Contraindications
Not validated for non-inflammatory or mechanical back pain
May be less reliable in patients with concurrent fibromyalgia due to symptom overlap
Does not assess axial inflammation directly; entirely patient-reported
How it Works
Formula
BASDAI = (Q1 + Q2 + Q3 + Q4 + (Q5 + Q6) / 2) / 5
Q1: Fatigue / tiredness (0–10)
Q2: Neck, back, or hip pain (0–10)
Q3: Joint pain / swelling (0–10)
Q4: Enthesitis (tenderness to touch or pressure) (0–10)
Q5: Morning stiffness severity (0–10)
Q6: Morning stiffness duration converted to 0–10:
0 = 0 min, 2 = 30 min, 4 = 60 min, 6 = 90 min, 8 = 120 min, 10 = ≥ 180 min
Score range: 0 – 10
Component Details
01
Q1 — Fatigue: "Rate the level of fatigue you have experienced over the past week"
02
Q2 — Spinal pain: "Rate the level of neck, back, or hip pain over the past week"
03
Q3 — Joint pain/swelling: "Rate pain/swelling in joints other than neck/back/hips over the past week"
04
Q4 — Enthesitis: "Rate discomfort from areas tender to touch or pressure over the past week"
05
Q5 — Stiffness severity: "Rate the severity of morning stiffness from time of waking over the past week"
06
Q6 — Stiffness duration: "How long does your morning stiffness last from waking?" (converted)
Clinical Pearls
Clinical Application
BASDAI is an entirely patient-reported outcome measure. It captures the patient's lived experience but is vulnerable to confounding from non-inflammatory pain. A high BASDAI should be corroborated by objective markers (CRP, ESR, or MRI of SI joints) before committing to biologic therapy. Many national guidelines use BASDAI ≥ 4 with objective inflammation as the threshold for anti-TNF eligibility.
Pitfalls to Avoid
Do not use BASDAI alone for biologic eligibility; always corroborate with CRP or MRI findings
BASDAI does not differentiate between axial and peripheral disease activity
The morning stiffness duration question requires conversion, a common source of scoring errors
Fibromyalgia or chronic pain syndromes can cause persistently elevated BASDAI without true inflammation
BASDAI has a ceiling effect and may not capture improvements at the high end of the scale
Next Steps
Score Interpretation Guide
| Score Range | Disease Activity | Clinical Action |
|---|---|---|
| < 4 | Low to moderate | Continue current therapy; monitor every 3–6 months |
| 4 – 7 | Moderate to high | Consider biologic if CRP/MRI confirms inflammation; optimise NSAIDs |
| > 7 | High (severe) | Escalate therapy; assess anti-TNF or IL-17 inhibitor initiation |
BASDAI 50 Response
The ASAS criteria define a BASDAI 50 response as ≥ 50% improvement from baseline plus an absolute change of ≥ 2 on the 0–10 scale. This is the most common primary endpoint in axSpA trials and is required for continued biologic reimbursement in many healthcare systems.
When to Reassess
Every 1–3 months during active treatment escalation
Every 3–6 months once treatment target is achieved
Before and after biologic initiation or switching
At each clinical visit when monitoring disease activity
The Evidence
Key Evidence
BASDAI demonstrated strong construct validity against physician global assessment in validation cohorts
ASAS/OMERACT endorse BASDAI as a core outcome measure for all axSpA clinical trials
BASDAI ≥ 4 with objective inflammation is the most common anti-TNF eligibility criterion worldwide
Longitudinal studies show BASDAI correlates with radiographic progression, functional decline, and quality of life
Primary Reference
A new approach to defining disease status in ankylosing spondylitis: the Bath Ankylosing Spondylitis Disease Activity Index.
Garrett S et al. • Journal of Rheumatology. 1994;21(12):2286-91
Assessment measures in ankylosing spondylitis
Zochling J • Current Opinion in Rheumatology. 2008;20(3):333-7
Origins & History
Development
Developed in 1994 by the Bath Ankylosing Spondylitis team at the Royal National Hospital for Rheumatic Diseases in Bath, UK. Six domains were selected through patient interviews, expert consensus, and psychometric validation. The BASDAI has since become the most widely used disease activity measure in AS and axial spondyloarthritis worldwide.
Last Comprehensive Review: 2026-07-17