The BASDAI Calculator is intended for patients with ankylosing spondylitis – a rare inflammatory condition that causes pain and stiffness in the spine. We have implemented the Bath Ankylosing Spondylitis Activity Index (BASDAI) – a validated diagnostic test that determines the current effectiveness of treatment. Please read our article below to learn more about it and its interpretation.

Moreover, if you want to know about your health and calculate the BASDAI result very quickly, our calculator will help you with that. We try to make our calculators as accurate and reliable as possible. However, this tool can never replace expert advice.

For more health related calculators, see our health category and find useful posts, such as Anion Gap, APGAR Score, PADUA Score or maybe ECG Boxes to Seconds.

BASDAI Score – Overview

In short, the index of ankylosing spondylitis disease activity is the gold standard for measuring and monitoring the value and activity of the disease.

Similarly, like BASFI, the spondylitis activity index consists of six analog scales that measure the severity of fatigue, ache in the spine and peripheral joints, localized sensitivity, and MS.

History of the BASDAI score

In 1994, rheumatologists, physiotherapists, and others who showed a special interest in researching ankylosing spondylitis conducted research and developed an index in a measuring tool applied in Bath consisting of 6 questions. It later became the gold standard for measuring and evaluating AS disease activity.

Benefits of BASDAI Score for Anti-TNF

Research conducted in the last few years gives us the knowledge that the calculator is associated with Anti-TNF treatment in people with spondylitis because it shows in more detail the condition of the patient and the activity of the disease.

Bath Ankylosing Spondylitis Disease Activity Index is used to initiate or maintain TNF-inhibitor therapy in routine clinical practice and is a standard parameter.

Also, in some patients with AS with a low activity index, the patient may complain of ache or have elevated inflammatory markers. In such cases, it may be helpful to assess activity by other measurement tools such as ASDAS.

Inaccurate measurement of disease activity can lead to inadequate treatment or treatment of patients with AS.

BASDAI Score – Formula

In order to get the results, we need to apply the following formula:

BASDAI = \frac {Q1 + Q2 + Q3 + Q4 + \frac {Q5 + Q6}{2}} {5}

Where Q means the points for each question.

What is Ankylosing Spondylitis?

Ankylosing spondylitis is a connective tissue disease that causes inflammation of the spine and large joints, leading to stiffness.

The condition is much more common in men than in women and usually occurs between 20 and 40. The cause of the condition is unknown.

Symptoms of ankylosing spondylitis

Morning stiffness (MS), which disappears after exercise, is very common. The lower back that is sore is associated with muscle cramps that often give way to bending forward. Therefore, people who often hold the body in this position become permanently hunched over. So, if certain treatments are carried out, they can be saved.

On the other hand, in others, the spine becomes erect and stiff. Back pain has been linked to anemia, loss of appetite, weight gain, and fatigue. The hip, knee, and shoulder are usually the first large joints in which pain occurs.

However, this is probably due to a combination of genetic and environmental factors. Unfortunately, there is no cure, but treatments improve symptoms and prevent them from getting worse. These include medication, exercise, physical therapy, and surgery in rare cases. Pharmacotherapy includes nonsteroidal anti-inflammatory drugs (e.g., naproxen and ibuprofen), disease-modifying antirheumatic drugs, and biological agents.

BASDAI Score Calculator Variables

Please answer the following questions.

1.How would you rate the general feeling of fatigue?

______ (0-10)

2. How would you describe the overall pain intensity in the neck, lower back, or hips?

______ (0-10)

3. How would you describe the overall intensity of swelling in other joints (excluding the neck, lower back and hips)?

______ (0-10)

4. How would you describe the overall level of discomfort caused to you by areas of the body sensitive to touch or pressure?

______ (0-10)

Issues related to morning stiffness (MS)

5. How would you assess the level of MS?

______ (0-10)

6. How long does your MS last from the moment you wake up?

0 1/2 1 1/2 2 hours and more

POINTS (0-10)__________

So, as already mentioned, each question has from 0 to 10 points score. We use the average of questions 5 and 6 because both refer to the same symptom – morning stiffness.

The mean of the last two questions related to morning braking is taken, and this value is added to the other information and divided by 5. Finally, the sum of the first four questions adds to the mean of the last two questions and divides by 5. The result is between 0 and 10.

What is the consequence of a higher level of disease?

A score greater than or equal to level 4 indicates suboptimal condition control. To sum up, these patients are usually good candidates to change their medical therapy or enroll in clinical trials that evaluate new drug therapies targeting ankylosing spondylitis.

Practical Example

Based on the above information, we use our calculator to enter these values:

  • Fatigue – 5
  • Spinal pain – 8
  • Swelling – 4
  • Areas of localized tenderness  – 6
  • MS duration 5
  • Morning stiffness severity 7

Bath Ankylosing Spondylitis Disease Activity Index is 5,8.

BASDAI Index Interpretation

A score of 4 or higher is a sign of suboptimal disease control.

Patients with higher level of disease, 4 points or more, are mostly:

  • Good candidates to change the way of treatment;
  • They may benefit from biological therapies; and
  • They may be candidates for enrolment in clinical trials evaluating new drug therapies.


The Index of Functional Ankylosing Spondylitis (BASFI) is a set of 10 questions we use to get the information about the degree of functional limitation in patients with ankylosing spondylitis (AS). The first eight questions relate to everyday tasks and depend on functional anatomy (bending, reaching, changing position, standing, turning, and climbing stairs). By comparison, the last two questions assess patients’ ability to cope with everyday life. So each item is on a scale of 0-10 points.

Likewise the BASFI, the Bath Index consists of six analog scales to measure fatigue severity, pain in the spine and peripheral joints, localized sensitivity, and morning stiffness.

However, the difference is in the numerical values for the determination.


What is the BASDAI score?

This is a validated diagnostic test that allows a physician, usually a rheumatologist, to determine the effectiveness of current drug therapy or the need to institute a new drug therapy for the treatment of Ankylosing spondylitis (AS). This calculator is one of a group of classification criteria for spondyloarthropathies.

What is a normal BASDAI score?

The score ranges from 0 to 10. Higher values indicate more active disease. Index score ≥4 is interpreted as the threshold above which the disease can be considered “active.”

What is BASDAI 50?

A major clinical response was defined as a 50% improvement or more, over time, of the initial Bath Ankylosing Spondylitis Disease Activity Index after 12 weeks of treatment with an active drug (infliximab )

What does BASDAI score 3 mean?

BASDAI is good, but you are on the verge of bad one which can worsen over time, so take care of your health.