Radiological scoring methods in ankylosing spondylitis: a comparison of the reliability of available methods

To assess intra and inter-rater reliability of available radiological scoring methods in ankylosing spondylitis (AS).

Two trained raters evaluated 44 complete sets of AS radiographs. The cervical and lumbar spine was graded from zero to 4 according to the Bath Ankylosing Spondylitis Radiology Index (BASRI). Hip joints were graded according to the BASRI-hip method. Sacroiliac (SI) joints were scored according to the New York method (0-4). The anterior and posterior sites of the lumbar spine were scored according to the Stoke Ankylosing Spondylitis Spinal Score (SASSS) method (0-72). Modified-SASSS was assessed by using the anterior sites of both the cervical and lumbar spine (0-72).

Both intra and inter-rater reliability were almost perfect for all the methods and intra-class correlation coefficient (ICC) for all the methods was relatively similar to each other. The BASRI-spine and BASRI-total showed intra and inter-rater ICC between 0.78 and 0.98. Both SASSS and modified--SASSS reached perfect intra and inter-rater reliability with ICC between 0.86 and 0.99. The ICC of the BASRI-hip was substantial to perfect, ranging from 0.77 to 0.88. Time spent to score a set of radiographs using the BASRI-spine was <45 seconds, whereas >60 seconds for both SASSS and mSASSS methods.

After training, all of these methods have demonstrated almost perfect intra and inter-rater reliability. The BASRI was easier to perform and less time consuming than SASSS methods.