What does BASDAI stand for?

BASDAI stands for Bath Ankylosing Spondylitis Disease Activity Index. It is a validated questionnaire used to measure disease activity in axial spondyloarthritis and ankylosing spondylitis, even though the name references ankylosing spondylitis specifically.

What is a normal BASDAI score?

BASDAI scores range from 0 to 10. Lower scores generally mean less active symptoms. There is no single normal score for everyone. Rheumatologists interpret your result in context. A score of 4 or above is often used in research and guidelines as a threshold for active disease, but treatment decisions depend on your full clinical picture.

How often should BASDAI be measured?

In clinic, BASDAI is often completed at appointments. For personal tracking, logging the underlying symptoms regularly (daily or several times a week) gives a more accurate picture than trying to recall how the past month felt from memory.

Can I calculate BASDAI myself?

Yes, if you have scores for all six questions on a 0 to 10 scale. Add fatigue, spinal pain, peripheral joint pain, enthesitis discomfort, and the average of morning stiffness severity and duration, then divide by five. Apps like Hurtl can calculate it from symptoms you log over time.

Does Hurtl calculate BASDAI automatically?

Hurtl tracks the symptom areas BASDAI is built around and calculates a BASDAI score from your logged data, so you can see trends between appointments rather than relying on recall alone.

1 June 2026

What Is BASDAI and How Is It Calculated?

By Tom, founder of Hurtl.

If you live with axial spondyloarthritis (axSpA) or ankylosing spondylitis (AS), you may hear your rheumatologist mention BASDAI at appointments. It sounds clinical, but the idea is straightforward: a short questionnaire that turns your symptoms into a single number your care team can track over time.

What is BASDAI?

BASDAI stands for Bath Ankylosing Spondylitis Disease Activity Index. It was developed in the 1990s as a way to measure how active axSpA symptoms are, using questions patients answer about their recent experience.

Despite the name referencing ankylosing spondylitis, BASDAI is widely used across axial spondyloarthritis, including non-radiographic axSpA. Rheumatologists use it to:

Monitor whether symptoms are improving or worsening
Compare your status between appointments
Support decisions about treatment, alongside examination and other tests

BASDAI is a patient-reported measure. That means it reflects how you say you have been feeling, not blood test results or imaging alone.

The six BASDAI questions

Each question is scored from 0 to 10, where 0 means no problem and 10 means the worst imaginable. You rate your experience over a recent period (commonly the past week):

Fatigue/tiredness overall
Spinal pain (neck, back or hips)
Joint pain/swelling in joints other than the spine
Discomfort from tender areas (enthesitis)
Morning stiffness severity when you wake up
Morning stiffness duration (also scored 0 to 10 based on how long stiffness lasts)

Questions 5 and 6 both relate to morning stiffness. One captures how stiff you feel; the other captures how long it lasts. That is why they are treated slightly differently in the formula.

How BASDAI is calculated

The BASDAI formula averages five components. Stiffness severity and duration are combined first:

BASDAI = (Q1 + Q2 + Q3 + Q4 + ((Q5 + Q6) / 2)) / 5

In plain terms:

Add your scores for fatigue, spinal pain, peripheral joint pain and enthesitis discomfort
Average your two morning stiffness scores
Add that stiffness average to the other four scores
Divide the total by five

The result is a single score from 0 to 10.

Worked example

Question	Score
Fatigue (Q1)	6
Spinal pain (Q2)	5
Peripheral joint pain (Q3)	2
Enthesitis discomfort (Q4)	3
Morning stiffness severity (Q5)	7
Morning stiffness duration (Q6)	6

Stiffness average: (7 + 6) / 2 = 6.5

BASDAI: (6 + 5 + 2 + 3 + 6.5) / 5 = 4.5

What do BASDAI scores mean?

There is no universal “good” or “bad” score that applies to everyone. Interpretation depends on your history, treatment and what your rheumatologist is looking for.

As a rough guide used in research and some treatment guidelines:

Lower scores (closer to 0): generally less active symptoms
Scores of 4 or above: often considered to suggest active disease that may warrant a treatment review

A single score on one day is a snapshot. What matters more is the trend: is BASDAI falling after starting a new medication, or creeping up before a flare becomes obvious?

This is not a diagnosis tool and not a reason to change treatment on your own. Always discuss results with your rheumatology team.

Why memory makes BASDAI hard at appointments

Many people are asked about symptoms they can barely remember. You might feel rough today but forget that stiffness lasted two hours most mornings last month. That recency bias can make BASDAI scores at clinic visits less accurate than your actual experience.

Daily tracking of the symptoms BASDAI is built on (fatigue, pain, stiffness duration, enthesitis) creates a log you can reference instead of guessing.

How tracking supports BASDAI in practice

You do not need to calculate BASDAI manually every day. The useful habit is logging the underlying symptoms consistently:

Morning stiffness duration and severity
Spinal and peripheral pain
Fatigue
Tender areas or enthesitis symptoms

Hurtl is built for axSpA tracking and calculates BASDAI from your logged data, so you can see how your score changes over weeks and share a clearer picture at appointments.

See our axial spondyloarthritis symptom tracker to get started, or read what’s the difference between AS and axSpA if you are still clarifying your diagnosis.

This article explains BASDAI for general information only. It is not medical advice, a diagnosis, or a recommendation to start, stop, or change treatment. BASDAI scores should be interpreted by your rheumatologist in the context of your full clinical picture. Hurtl is not a medical device and does not provide clinical monitoring or treatment decisions.