Comparison of the Bath Ankylosing Spondylitis Radiology Index and the modified Stoke Ankylosing Spondylitis Spine Score in Turkish patients with ankylosing spondylitis

The objective of the present study was to compare two radiographic scoring methods (the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) and the Bath Ankylosing Spondylitis Radiology Index-spine (BASRI-spine)) in terms of reliability, construct validity, and feasibility in Turkish ankylosing spondylitis (AS) patients. The study involved seventy-four patients. The patients were evaluated with 100-mm visual analog scale (VAS) for pain, global assessment of patient, and global assessment of doctor. The laboratory evaluations of patients comprised erythrocyte sedimentation rate and serum C-reactive protein. Bath AS Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI), Bath AS Metrology Index (BASMI), and Bath AS Radiology Index (BASRI) were calculated. Bilateral cervical, lumbar spine, and anteroposterior pelvis radiographs of all patients were obtained and evaluated by two radiologists. Each radiograph was scored by two scoring methods, mSASSS and BASRI-spine, and these methods were tested according to the aspects of the Outcome Measures in Rheumatology Clinical Trials filter: reliability, construct validity, and feasibility. The BASRI-spine reached intra- and interobserver intraclass correlation coefficient (ICC) of 0.726 and 0.689, respectively. The mSASSS scores more reliable, with ICC of 0.831 and 0.840, respectively. The BASMI and BASFI correlated significantly with the two scoring systems, respectively (mSASSS r: 0.557, r: 0.319; BASRI-spine r: 0.605, r: 0.285). For the two methods, the magnitude of the correlation with disease duration was similar (mSASSS p < 0.01 and BASRI p < 0.01), but no significant correlation was observed when compared to the BASDAI. It is known that the BASRI-spine is a feasible method that reliably detects damage in patients with AS. However, the present authors believe that, in AS patients, mSASSS should be the radiological scoring method to choose because of less radiation exposure, along with excellent intra- and interobserver reliability.