Assessment of outcome in ankylosing spondylitis: an extended radiographic scoring system

Abstract

Objective: To develop and validate an extensive radiographic scoring system for ankylosing spondylitis (AS).

Methods: The Stoke Ankylosing Spondylitis Spinal Score (SASSS) was modified by adding a score for the cervical spine and defining squaring. This modified SASSS (mSASSS) is the sum of the lumbar and cervical spine score (range 0-72). 370 lateral views of the lumbar and cervical spine were used for development of the mSASSS, standardisation of observers, and for studying reliability. In a 48 week NSAID study of 57 patients, change over time and construct validity were studied.

Results: Interobserver correlations of the lumbar and cervical spine scores were good (r>0.95). The interobserver duplicate error was 0.55 in a range from 0 to 36. The mean change in the cervical and lumbar spine scores between weeks 0 and 48 of all patients was 1.45 (range 0-6.0) and 1.06 (0-5.0), respectively (paired t testing, p<0.001). Change in radiological score was seen in 36/57 (63%) patients (lumbar and cervical spine 11, cervical spine 12, lumbar spine 13 patients).

Conclusion: The mSASSS is useful for assessing extensive radiographic damage in AS. It is reliable, detects changes over 48 weeks, and shows a satisfactory face and construct validity.

Figures

Figure 1

Radiographic changes from weeks 0 to 48 for all patients, men and women separately. CSW, cervical spine women; CSM, cervical spine men; LSW, lumbar spine women; LSM, lumbar spine men; mSASSS, modified Stoke Ankylosing Spondylitis Score in all patients; mSASSSW, mSASSS women; mSASSSM, mSASSS men.