The Bath Indices

 BASFI- Bath AS Functional Index

The BASFI is a set of 10 questions designed to determine the degree of functional limitation in those with AS. It is measured using a visual analogue scale (ranging from 0 being easy and 10 being impossible) and the questions are focused on the person’s ability to perform specific functional tasks. The first 8 questions consider activities related to functional anatomy, such as putting on socks with or without help and climbing steps with or without using a handrail. The final two questions assess the patients’ ability to cope with everyday life. It is included in the ASAS core sets for AS assessment. The BASFI has shown to have high levels of validity and reliability when measuring functional ability in AS (Ruof and Stucki 1999).

BASDAI: Bath AS Disease activity Index

The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) is the gold standard for measuring and following disease activity in Ankylosing Spondylitis (Garrett et al 1994).
Like the BASFI, the BASDAI consists of 10cm visual analogue scales used to answer 6 questions pertaining to the 5 major symptoms of AS:
- Fatigue
- Spinal pain
- Joint pain/swelling
- Areas of localized tenderness
- Morning stiffness

 Intensity
 Duration
 The questions are answered on a 10 cm VAS, anchored with the labels “none” and “very severe” at either end of the first five questions, and with "0 hours” and “two hours” at either end of the question on duration of morning stiffness. The mean of the two scores for morning stiffness counts as one variable. The final score is defined by calculating the mean of the five items. Final scores range from 0 (best) to 10 (worst).
 A BASDAI score >4 is internationally accepted to indicate active disease, and most clinical trials of therapy in AS now require that patients have active disease as defined by a BASDAI score of >4 for inclusion.

When clinically tested, results showed:
1. BASDAI to be a quick and simple index, taking between 30 seconds and 2 minutes to complete.
2. BASDAI demonstrated statistically significant (p<0.001) reliability.
3. The individual symptoms and the index as a whole demonstrated good score distribution, using 95% of the scale.
4. Following a 3 week physiotherapy course, the BASDAI showed a significant
(p=0.009) 16.4% score improvement, therefore demonstrating a sensitivity to change.
To conclude, the BASDAI is user friendly, highly reliable, reflects the entire spectrum of the disease, and is sensitive to clinical changes.

BASMI- Bath AS Metrology Index

To accurately assess axial status (cervical, dorsal and lumbar spine, hips and pelvic soft tissue) of individuals with AS and from these derive a metrology index to define clinically significant changes in spinal mobility.

Five clinical measurements were included in the index:
1. Cervical rotation (degrees of motion)
2. Tragus to wall distance (centimetre tape measure)
3. Lumbar side flexion (centimetre tape measure)
4. Modified Schober Test centimetre tape measure)
5. Intermalleolar distance (centimetre tape measure)
A BASMI score from between 0 to 10 is calculated after the clinical exam is performed and each of the 5 measurements is obtained. The range of severity 0-10 reflects mild to moderate disease activity and functional ability in the spinal column. The higher the BASMI score the more severe the patient’s limitation of movement due to their AS.

BAS-G: Bath AS Patient Global score

The impact of AS from the patients’ perspective encompasses all aspects of disease including activity, function and structural damage, in one summary measure. The patient global assessment is useful in clinical practice, and may be the single most responsive measure in this setting.
The Bath Ankylosing Spondylitis Global score (BAS-G) is consistent with the other measures in the core set, utilizing the ‘in the last week’ approach to obtain a snapshot of current patient status but also it also refers to the patient’s average well-being over the last 6 months, which can be helpful to describe longer-term disease progression.
The BAS-G consists of two questions which ask patients’ to indicate, on a 10cm VAS, the effect the disease has had on their well-being over the
 last week
 last six months.
The mean of the two scores gives a BAS-G score of 0 – 10. The higher the score, the greater the perceived effect of the disease on the patient’s well-being.