BASMI Score (Bath Ankylosing Spondylitis Metrology Index)

BASMI helps define clinically significant changes in spinal mobility of Ankylosing Spondylitis patients.

Refer to the text below the calculator for more information about the BASMI and its usage.


BASMI was created to help clinicians accurately assess axial status (through five measurements) of individuals suffering from Ankylosing Spondylitis.

The measurements are then interpreted to derive a metrology index to define clinically significant changes in spinal mobility.


The five clinical measurements used to derive BASMI are:

  • Cervical Rotation;
  • Tragus to Wall;
  • Lumbar Side Flexion;
  • Lumbar Flexion (Modified Schober’s);
  • Intermalleolar Distance.

Interpretation: The higher the BASMI score, the more severe the patient’s limitation of movement due to Ankylosing Spondylitis.


Cervical Rotation
Tragus to Wall
Lumbar Side Flexion
Lumbar Flexion (Modified Schober’s)
Intermalleolar Distance
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About BASMI

BASMI was created to help clinicians accurately assess axial status (through five measurements) of individuals suffering from Ankylosing Spondylitis. The measurements are then interpreted to derive a metrology index to define clinically significant changes in spinal mobility.

The five clinical measurements used to derive the BASMI score are:

  • Cervical Rotation;
  • Tragus to Wall;
  • Lumbar Side Flexion;
  • Lumbar Flexion (Modified Schober’s);
  • Intermalleolar Distance.

For Cervical Rotation, Tragus to Wall and Lumbar Side Flexion, a mean between left and right measurements should be used.

After the clinical exam is performed, there are two methods available to interpret the 5 measurements and obtain the final score. Originally, the Jenkinson et al. study devised the 2-step table, presented below.

  Mild 0 Moderate 1 Severe 2
Cervical rotation
(Mean of L & R)
> 70 deg 20 –70 deg < 20 deg
Tragus to wall
(Mean of L & R)
< 15 cm 15 – 30 cm > 30 cm
Lumbar side flexion
(Mean of L & R)
> 10 cm 5 – 10 cm < 5 cm
Lumbar Flexion
(Modified Schober’s)
> 4 cm 2 – 4 cm < 2 cm
Intermalleolar Distance > 100 cm 70 – 100 cm < 70 cm

An expansion of the original table is more commonly used in clinical practice and research. Some studies consider that the two tables have similar sensitivity to change whilst others, such as van der Heijde et al. found that the 10-step version (presented below and used in the BASMI calculator) is superior in sensitivity.

Item / Points 0 1 2 3 4 5 6 7 8 9 10
Tragus to Wall ≤10 10.1-12.9 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 Flexion (Modified Schober’s) ≥7.0 6.4-6.9 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
Intermalleolar Distance ≥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 30.1-39.9 ≤30
Cervical Rotation ≥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
Lumbar Side Flexion ≥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 1.3-3.2 ≤1.2

The scores from the 10-step table for each of the five measurements are summed and divided by five to obtain the final score, which ranges between 0 and 10. The higher the BASMI score, the more severe the patient’s limitation of movement due to Ankylosing Spondylitis.

Other scores that evaluate AS, part of the Bath indices include:

 

References

Original reference

Jenkinson TR, Mallorie PA, Whitelock HC, Kennedy LG, Garrett SL, Calin A. Defining spinal mobility in ankylosing spondylitis (AS). The Bath AS Metrology Index. J Rheumatol. 1994; 21(9):1694-8. PMID: 7799351.

Other references

1. van der Heijde D, Landewé R, Feldtkeller E. Proposal of a linear definition of the Bath Ankylosing Spondylitis Metrology Index (BASMI) and comparison with the 2-step and 10-step definitions. Ann Rheum Dis. 2008; 67(4):489-93.

2. Chilton-Mitchell L, Martindale J, Hart A, Goodacre L. Normative values for the Bath Ankylosing Spondylitis Metrology Index in a UK population. Rheumatology (Oxford). 2013; 52(11):2086-90.

3. Zochling J. Measures of symptoms and disease status in ankylosing spondylitis: Ankylosing Spondylitis Disease Activity Score (ASDAS), Ankylosing Spondylitis Quality of Life Scale (ASQoL), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Global Score (BAS-G), Bath Ankylosing Spondylitis Metrology Index (BASMI), Dougados Functional Index (DFI), and Health Assessment Questionnaire for the Spondylarthropathies (HAQ-S). Arthritis Care Res (Hoboken). 2011; 63 Suppl 11:S47-58.


Specialty: Disability

System: Musculoskeletal

Objective: Evaluation

Type: Index

No. Of Items: 5

Year Of Study: 1994

Abbreviation: BASMI

Article By: Denise Nedea

Published On: December 7, 2022

Last Checked: December 7, 2022

Next Review: December 7, 2027