BASDAI Score Calculator

Created by Joanna Michałowska, PhD candidate
Reviewed by Dominik Czernia, PhD, Jack Bowater and Łucja Zaborowska, MD, PhD candidate
Based on research by
Garrett S, Jenkinson T, Kennedy LG, Whitelock H, Gaisford P, Calin A. A new approach to defining disease status in ankylosing spondylitis: the Bath Ankylosing Spondylitis Disease Activity Index.; The Journal of Rheumatology; December 1994
Last updated: Jun 05, 2023

The BASDAI score calculator is dedicated to patients with Ankylosing Spondylitis - a rare inflammatory disease that causes pain and stiffness in the spine. Our tool has implemented the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) - a validated diagnostic test, which determines the effectiveness of the current treatment. Read the article below to find out more about the BASDAI score and the BASDAI index interpretation.

Feel free to check out our other tools assessing the severity of various conditions: pneumonia severity index (the PSI calculator), Crohn's disease activity index (the CDAI), or the model for end-stage liver disease (the MELD calculator).

⚠️ We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace professional medical advice.

What is Ankylosing Spondylitis (AS)? Ankylosing Spondylitis definition.

Ankylosing Spondylitis is a rare type of arthritis which is associated with pain and stiffness in the joints and spine. This is a lifelong condition and stiffness of the affected joints generally worsens over time. The signs and symptoms appear gradually, usually starting in people 20 and 30 years old and located in the lower back.

Ankylosing Spondylitis symptoms may include:

  • Back pain and stiffness;
  • Pain and swelling in other parts of the body;
  • Tiredness;
  • Weight loss;
  • Fever; and
  • Anterior uveitis.

The cause of this condition is not known, but it is probably due to a combination of genetic and environmental factors, as most of the affected patients have a specific human leukocyte antigen (HLA-B27 antigen). There is no cure for AS, but there are treatments to improve symptoms and prevent it from worsening. Those include medication, exercise, physical therapy, and surgery in rare cases. The pharmacotherapy include nonsteroidal anti-inflammatory drugs (e.g. naproxen and ibuprofen — you can learn how to calculate their dosage with Omni's ibuprofen dosage calculator and aleve dosage calculator), disease-modifying antirheumatic drugs, and biologic agents.

Bath Ankylosing Spondylitis Disease Activity Index - BASDAI score meaning

The Bath Ankylosing Spondylitis Disease Activity Index, BASDAI in short, is a quick and simple index to determine the effectiveness of the current drug therapy for a patient suffering from AS. The test was created in 1994 in Bath (England) by a research team consisting of rheumatologists, physiotherapists, and other specialists. Completing it takes between 30 secs and 2 mins.

The BASDAI consists of 6 questions relating to the five major symptoms of AS:

  • Fatigue;
  • Spinal pain;
  • Joint pain or swelling;
  • Areas of localized tenderness; and
  • Morning stiffness duration and severity.

Each of the questions has a 0-10 scale, where 0 means that there is no problem and 10 that the problem is severe.

BASDAI score calculator - how does it work?

As mentioned before, BASDAI score calculator consists of six questions. Answer all of them by choosing the most appropriate answer.

0 means that the patient does not have a problem with the symptom the question relates to, where the highest score of 10 means that the problem is severe.

BASDAI index interpretation and score

The formula below shows how do we calculate BASDAI score:

BASDAI=(Q1+Q2+Q3+Q4+Q5+Q62)5\scriptsize\begin{split} &\mathrm{BASDAI} \!=\! \frac{\left(Q_1\! +\! Q_2\! + \!Q_3\!+\!Q_4\!+ \!\frac{Q_5 + Q_6}{2}\right) }{5} \end{split}

where QQ means the points for each question.

As we mentioned before, each question can score from 0 to 10 points. The average of question 5 and 6 is used because they both relate to the same symptom - morning stiffness.
After performing all of the calculations, the total BASDAI score can range from 0 to 10 points.

What is the BASDAI Index interpretation?

It was established that score of 4 or greater is a sign of suboptimal control of the disease.

Patients who score 4 or more are usually:

  • Good candidates for a change in their treatment;
  • May benefit from biologic therapies; and
  • May be candidates for enrolment in clinical trials evaluating new drug therapies.
Joanna Michałowska, PhD candidate
Please, answer each question relating to the past week.

How would you describe the overall level of the following symptoms you have experienced/had?

0 - None
AS neck, back or hip pain
0 - None
Pain/swelling in joints
0 - None
Discomfort from any areas tender to touch or pressure
0 - None
Morning stiffness
0 - None
Morning stiffness duration
0 hours
BASDAI score
A score higher than or equal to 4 suggest suboptimal control of the disease. These patients are usually good candidates for either a change in their medical therapy or for enrollment in clinical trials evaluating new drug therapies directed at Ankylosing Spondylitis.
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