BASDAI Score Calculator

The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) relies on six patient-reported questions, usually answered on a visual analog scale or numerical rating scale from 0 (none) to 10 (very severe). These questions capture fatigue, spinal pain, peripheral joint pain, localized tenderness, and the severity and duration of morning stiffness. The mathematical formula averages these inputs by grouping specific symptom domains. First, the scores for fatigue, spinal pain, peripheral discomfort, and localized tenderness (Questions 1 through 4) are added together. Next, the average of the two morning stiffness questions (Questions 5 and 6) is calculated to account for stiffness severity and duration. Finally, these two combined values are added together and divided by 5 to yield a final composite score between 0 and 10.

Imagine a patient with ankylosing spondylitis evaluating their symptoms over the past week. They input the following values into the calculator: Fatigue (Question 1) = 6, Spinal Pain (Question 2) = 5, Peripheral Pain and Discomfort (Question 3) = 4, Localized Tenderness (Question 4) = 5, Morning Stiffness Severity (Question 5) = 6, and Morning Stiffness Duration (Question 6) = 8. First, we sum the first four questions: 6 + 5 + 4 + 5 = 20. Next, we average the morning stiffness questions: (6 + 8) / 2 = 7. We then add the stiffness average to the sum of the first four questions: 20 + 7 = 27. Finally, we divide by 5: 27 / 5 = 5.4. The resulting BASDAI score of 5.4 indicates active disease and helps the patient discuss potential treatment adjustments with their rheumatologist.

Consistency is key when monitoring disease activity through patient-reported outcomes. Always evaluate your symptoms based on the past week, rather than just a single day, to account for daily fluctuations. Share your tracked scores consistently with your rheumatology care team during routine appointments to provide an objective trend line of how well your current medication regimen is performing. Remember that the BASDAI score is a subjective measure and should always be interpreted alongside objective lab markers like C-reactive protein (CRP) and imaging studies.