The Bath Indices

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Intoduction

The Bath Indices is a functional and disease activity indices used to aid diagnosis and monitor disease activity in people with Ankylosis Spondilitis (AS). It is made up of four indices which are the Bath Ankylosis Spondylitis Metrology Index(BASMI), the Bath Ankylosis Spondylitis Functional Index (BASFI), the Bath Ankylosis Spondylitis Disease Activity Index (BASDAI), and the Bath Ankylosis Spondylitis Patient Global Score (BAS-G). All indices produce a score out of 10, giving a clear numerical outcome each time the indices are used. Also, the four indices have been studied for reliability, speed, variability, reproducibility, and sensitivity to change.

Objective

The Bath Ankylosis Spondylitis Functional Index (BASFI), is a set of 10 questions designed to determine the degree of functional limitation in patients with Ankylosis Spondylitis (AS). The 10 questions were chosen with a major input from patients with AS. The first 8 questions are pertaining to everyday tasks and dependent on functional anatomy (bending, reaching, changing position, standing, turning, and climbing steps with or without rail) while the final 2 questions assess the patients’ ability to cope with everyday life. Each item is scored on the scale of 0-10.

A 10 cm visual analog scale (VAS) was used to answer the questions but it is now being replaced by a numerical pain rating scale (NRS) in many centers.

Intended Population

It is a patient self-report questionnaire for patient with Ankylosis Spondylitis.

Method of Use

BASFI is made up of 10 questions which are related to activities of daily living and are scored with a rating scale from 0 (no functional impairments) to 10 (maximal impairment). Each question is answered on a 10 cm horizontal VAS or a numeric response scale (NRS). A score of 0 indicates the activity was easy and a score of 10 indicates the activity was impossible for the person to accomplish.

All scores from the questions 1-10 are added and then divided by 10. The mean of the individual scores is calculated to give the overall index score. A higher score indicates a higher degree of functional limitations.

The BASFI Items and Scoring

The following is referenced from National Ankylosis Spondylitis Society booklet.

Please indicate your level of ability with each of the following activities during the past week.

1) Putting on your socks or tights without help or aids (e.g sock aid).
1 2 3 4 5 6 7 8 9 10
2) Bending from the waist to pick up a pen from the floor without aid.
1 2 3 4 5 6 7 8 9 10
3) Reaching up to a high shelf without help or aids (e.g helping hand).
1 2 3 4 5 6 7 8 9 10
4) Getting up from an arm less chair without your hands or any other help.
1 2 3 4 5 6 7 8 9 10
5) Getting up off the floor without help from lying on your back.
1 2 3 4 5 6 7 8 9 10

6 ) Standing unsupported for 10 minutes without discomfort.
1 2 3 4 5 6 7 8 9 10
7) Climbing 12-15 steps without using a handrail or walking aid.
1 2 3 4 5 6 7 8 9 10

8) Looking over your shoulder without turning your body.

1 2 3 4 5 6 7 8 9 10

9) Doing physically demanding activities (e.g physiotherapy exercises, gardening or sports).
1 2 3 4 5 6 7 8 9 10

10) Doing a full days activities whether it be at home or at work.
1 2 3 4 5 6 7 8 9 10

Evidence

The BASFI satisfies the criteria required of a functional index: it is quick and easy to complete, is reliable and is sensitive to change across the whole spectrum of disease. Furthermore, over the 3 week period of inpatient treatment, the BASFI revealed a significant improvement in function (20%, p = 0.004) while there was a less impressive change in the Dougados functional index (6%, p = 0.03). This demonstrates the superior sensitivity of the BASFI: Consistency was good for both indices (p < 0.001), as was the relationship between patient perception of function and function as assessed by an external observer (p < 0.001).

Reliability

When patients were assessed on their actual performance of eight items from the BASFI representing activities of daily life, adequate to excellent test-retest reproducibility was shown. A significant association between the BASMI and BASFI has also been demonstrated indicating the importance of spinal mobility on an individual’s functional status.

Validity

Calin et al. (1994) compared BASFI with Dougados functional index, it was found that the BASFI demonstrates a significant improvement in function while there was less change in the Dougados score.

Internal consistency reliability and construct validity of BASFI was deemed acceptable by the authors, but they also mentioned that random measurement error of BASFI was not negligible.

Haywood et al. (2005) reported that BASFI is one of three AS assessment instruments with the most extensive evidence for validity through comparison with instruments that measure similar or related constructs, and/or with measures of mobility.

Responsiveness

There was 20% (P = 0.004) improvement in function over 3 weeks versus 6% (P = 0.03) improvement demonstrated by the Dougados functional index during the physiotherapy treatment over the same 3-week period.

Miscellaneous

One of the benefits of the scale in the way it is administered resides in the visual analogue scale which is a lot easier and quicker to use for patients, although it requires a bit of interpretation from the clinician.

Objective

The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) is the gold standard for measuring and following disease activity and thus functional status in the person with Ankylosing Spondylitis.

Like the BASFI, the BASDAI consists of six 10-cm horizontal visual analog scales to measure severity of fatigue, spinal and peripheral joint pain, localized tenderness, and morning stiffness (both qualitative and quantitative). This VAS has now been replaced by a numerical rating scale (NRS) in many centres.

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).

Intended Population

Persons with Ankylosis Spindylitis.

Method of Use

• BASDAI is a quick and simple index taking between 30 secs and 2 mins to complete. It is a self-reported questionnaire that is made up of 6 questions related to 5 major symptoms: fatigue, spinal pain, joint pain/swelling, areas of localized tenderness, morning stiffness. Each question is answered on a  ten centimeter visual analog scales. A score of 0 = none (no symptoms), and a score of 10 = very severe symptoms.

• To calculate the mean score, the scores for questions 1 – 4 is added together. The mean for questions 5 and 6 is calculated.

• The mean measurement (score) of questions 5 and 6 is added to the scores from questions 1 to 4. This total is then divided by 5 to give the average. This is the BASDAI score. The higher the BASDAI score, the more severe the patient’s disability due to their AS.

The BASDAI Item and Scoring

Please tick the box which represents your answer.
All questions refer to last week. (i.e. )
1. How would you describe the overall level of fatigue/tiredness you have experienced?

       1 2 3 4 5 6 7 8 9 10
none                         very severe

2. How would you describe the overall level of AS neck, back or hip pain you have had

       1 2 3 4 5 6 7 8 9 10
none                         very severe

3. How would you describe the overall level of pain/swelling in joints other than neck, back or hips you have had?

      1 2 3 4 5 6 7 8 9 10
none                         very severe

4. How would you describe the overall level of discomfort you have had from any areas tender to touch or pressure?

      1 2 3 4 5 6 7 8 9 10
none                         very severe

5. How would you describe the overall level of morning stiffness you have had from the time you wake up?

      1 2 3 4 5 6 7 8 9 10
none                         very severe

0              1               2 or more
hr             hr              hrs

6. How long does your morning stiffness last from the time you wake up?

      1 2 3 4 5 6 7 8 9 10
none                         very severe

0            1                2 or more
hr           hr               hr

Reliability

BASDAI demonstrated statistically significant (p<0.001) reliability.

Test-retest reliability across the scale responses where said to be good (who said that it is good).

Validity

When compared to a previous disease activity index it is felt that BASDAI is superior in terms of symptoms considered and their weighting. This may be due to the input from patients with AS when the index was developed. The BASDAI was also found to be superior in all aspects to the Newcastle Enthesis Index.

The validity of BASDAI was further assessed by Calin et al (1999) have further. They concluded that the BASDAI has excellent content validity.

Responsiveness

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.

Objective

BASMI is a composite index used internationally in research and clinical practice. It is used to asses clinically significant changes in spinal mobility. With this scale in mind, clinicians and patients may have expectations that a score of zero is representative of normal spinal involvement in a healthy population(4). 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.

Intended Population

The BASMI is ascoring system used to assess the spinal mobility of ankylosis spondylitis.

Method of Use

• The BASMI takes only 7 minutes to apply. It is an index composed of five mobility tests; Cervical rotation, Tragus to wall distance, Lumbar side flexion, Modified Schober’s, Intermalleolar distance.

• The scale of the BASMI ranges from 0 to 10, where 0 is no mobility limitation and 10 is very severe limitation.

• To calculate the scores for each measurement i.e cervical rotation, tragus etc. A mean of the left and right measurements is taken. The scores of each measurements are added together, and this will provide a figure out of 50. Divide this by 5 to give the BASMI score. The higher the BASMI score the more severe the patient's limitation of movement due to their AS.

Calculating the score for each of the BASMI measurement

	0	1	2	3	4	5	6	7	8	9	10
Tragus to Wall (cm)	<10	10-12.9	13-15.9	16-18.9	19-21.9	22-24.9	25-27.9	28-30.9	31-33.9	34-36.9	≥37
Lumbar Side Flexion (cm)	≥20	18-19.9	15.9-17.9	13.8-15.8	11.7-13.7	9.6-11.6	7.5-9.5	5.4-7.4	3.3-5.3	1.2-3.2	<1.2
Lumbar Flexion (modified Schober’s) (cm)	>7.0	6.4-7.0	5.7-6.3	5.0-5.6	4.3-4.9	3.6-4.2	2.9-3.5	2.2-2.8	1.5-2.1	0.8-1.4	≤0.7
Cervical Rotation (degrees)	≥85	76.6-84.9	68.1-76.5	59.6-68	51.1-59.5	42.6-51	34.1-42.5	25.6-34	17.1-25.5	8.6-17	≤8.5
Intermalleolar Distance (cm)	≥120	110-119.9	100-109.9	90-99.9	80-89.9	70-79.9	60-69.9	50-59.9	40-49.9	30-39.9	<30

A guide to obtaining the BASMI measurement

Below is a guide for clinicians on how to obtain the five BASMI measuements in a standardised fashion. It is recognised that this represents an ‘ideal’ scenario that may need adapting depending on tht patient’s individual posture/circumstances. However, it is recommended that any changes be carefully documented to ensure measurements are accurate each time the measurements are taken. With all measurements, the patient should be comfortable and suitably undressed.

Measure	Starting Position	Method	Notes
Tragus to wall	Standing bare feet; back to wall; knees straight; scapulae, buttocks, heels against wall; shoulders level; outer edges of feet 30 cm apart & feet parallel. Ensure head in as neutral position (anatomical alignment) as possible.	Patient draws chin in as far as possible (retraction). The examiner has both eyes open and side of face against wall and measures the distance between the tragus of the ear & the wall, using a rigid ruler	Ensure no cervical extension, rotation, flexion or side flexion occurs. Best to use a wall without a skirting board. Ensure retraction is maintained whilst both sides are measured.
Lumbar Side Flexion	Standing bare feet; back to wall; knees straight; scapulae, buttocks, heels against wall; shoulders level; outer edges of feet 30 cm apart & feet parallel.	Before any movement occurs, keeping arms, wrist & fingers straight and shoulders depressed measure from tip of middle finger to floor. With arms relaxed by the sides, patient reaches towards floor by side flexing and maintaining shoulder depression. Re-measure from tip of middle finger to floor. Difference between 2 measurements represents amount of side flexion. Repeat on other side.	Ensure patient keeps arms, fingers & knees straight and heels on floor. Ensure any forward flexion, extension or rotation of the trunk is avoided. Best to use a wall without a skirting board. May need to accommodate a leg length discrepancy with block under foot. (NB: Ensure all conditions are recorded for accurate measurements)
Lumbar Flexion (modified Schober’s)	Standing with outer edges of bare feet 30 cm apart and feet in line. Examiner marks a first point midway between the Dimples of Venus, a second point is marked 10 cm above this & a third 5 cm below the first to give a 15 cm line.	Patient flexes forward from the waist with knees fully extended. The distance between the upper and lower 2 marks is measured. Any increase beyond 15 cm represents the amount of movement achieved.	At the end of the movement, you may choose to allow slight knee flexion to decrease influence of hamstrings. This should be documented.
Cervical Rotation	Patient supine on plinth. Forehead horizontal & head in neutral position. May need to use pillow, books or foam block to achieve this. Carefully document to ensure same set up on future re-assessments.	Use goniometer / inclinometer as per manufacturer’s instructions. Patient rotates his/her head as far as possible, keeping shoulders still. Measure both sides.	Ensure no neck flexion/side flexion occurs. If good range of movement may need to lie near edge of bed to allow movement to occur
Intermalleolar Distance	Patient lies supine on the floor or a wide plinth. Knees in extension	Keeping knees straight & legs in contact with the resting surface, patient is asked to take legs as far apart as possible. Distance between the medial malleoli is measured	Measure quickly as movement can be painful. Be ready to measure before asking patient to achieve movement.

Reliability

Inter and intra – rater reliability has been explored and for repeat assessments of the same participant by the same physiotherapist, differences of BASMI of 1.0 or less are within bounds of error; and likewise, differences of 1.0 or less are within bounds of error if different physiotherapists perform the assessments. Only changes above these limits can be confidently interpreted as true clinical change.

Validity

At the level of significance (p<0.001), the BASMI proved to be accurate and reproducible for both inter- and intra- observer variability.

Responsiveness

The sensitivity of the index to change was found to be significant (p<0.01) regardless of the disease severity.
Five clinical measurements were included in the index:

Objective

It is used to assess the effect of AS on the patient’s well being. It 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 and last 6 months. The VRS has now been replaced by numerical rating scales (NRS) in many centres.

Intended Population

The BASMI is used for persons with AS.

Method of Use

• 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 and 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.
  

Validity

BAS-G has good construct validity and correlated more strongly with each component of BASDAI and BASFI than with BASMI or with gender.

Responsiveness

BAS-G demonstrated statistically significant (p<0.001) sensitivity to change. Jones et al, acknowledged that BAS-G cannot stand alone, and should be one element of a complete assessment. However, an index of this type provides a numerical value to the patient’s sense of well being. This allows for comparison between consultations, especially when patients may not necessarily be seen by the same clinician on each occasion.The authors of the index conclude that they have formalized and validated a simple, frequently asked question.