The Bath Ankylosing Spondylitis Patient Global Score (BAS-G)

Area of Science:

• Rheumatology
• Clinical Assessment
• Patient-Reported Outcomes

Background:

• Ankylosing spondylitis (AS) lacks a comprehensive objective measure for patient well-being.
• Existing measures like BASDAI, BASFI, and BASMI assess disease activity, function, and spinal mobility, respectively.
• A global assessment tool is needed to capture the overall impact of AS on patients.

Purpose of the Study:

• To design and validate a global measure, the Bath Ankylosing Spondylitis Patient Global Score (BAS-G).
• To assess BAS-G's construct validity, predictive validity, and test-retest reliability.
• To determine the correlation between BAS-G and established AS assessment indices.

Main Methods:

• Pilot study for wording selection.
• Validation using 392 AS patients.
• Assessed construct validity, predictive validity, and test-retest reliability.
• Correlations with BASDAI, BASFI, and BASMI were calculated; multiple regression was used.

Main Results:

• BAS-G demonstrated excellent test-retest reliability (1 week r=0.84, 6 months r=0.93).
• BAS-G showed strong correlations with BASDAI (r=0.73) and BASFI (r=0.54), indicating disease activity and function are key to well-being.
• The score was sensitive to change, with significant improvement in in-patient scores over a 2-week treatment period (P<0.001).

Conclusions:

• BAS-G is a valid, reliable, and sensitive global measure for assessing the impact of AS on patient well-being.
• Disease activity and functional ability are major determinants of patient well-being in AS.
• BAS-G complements existing measures by providing a holistic patient perspective.