The Discriminative Values of the Bath Ankylosing Spondylitis Disease Activity Index, Ankylosing Spondylitis Disease Activity Score, C-Reactive Protein, and Erythrocyte Sedimentation Rate in Spondyloarthritis-Related Axial Arthritis.

OBJECTIVES

The aims of this study were to determine the effectiveness of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score-C-Reactive Protein (ASDAS-CRP), Ankylosing Spondylitis Disease Activity Score-Erythrocyte Sedimentation Rate (ASDAS-ESR), and inflammatory markers in screening for axial-joint inflammation as detected by magnetic resonance imaging (MRI) and to find out factors that could affect scoring of the indices.

METHODS

One hundred fifty-three Chinese spondyloarthritis patients were recruited. Clinical data and BASDAI were collected, and Bath Ankylosing Spondylitis Metrology Index was measured. Serum ESR and CRP were checked, and ASDAS-ESR and ASDAS-CRP were calculated. Radiographs of cervical and lumbar spine were performed for modified Stoke Ankylosing Spondylitis Spinal Score. All patients underwent MRI of the spine and sacroiliac joints. Axial-joint inflammation was evaluated by Spondyloarthritis Research Consortium of Canada MRI indices. Multivariate linear regressions were used to determine potential factors that could affect disease activity indices. Receiver operating characteristic curve was used to determine the effectiveness in screening for axial-joint inflammation.

RESULTS

BASDAI was associated with current back pain (B = 0.89, P = 0.01), ASDAS-CRP with current back pain (B = 0.74, P = 0.04), and current dactylitis (B = 0.70, P = 0.03) ASDAS-ESR with current back pain (B = 0.95, P = 0.01), and current dactylitis (B = 0.99, 0.002). The ROC curve revealed that CRP was the only variable that successfully discriminated spondyloarthritis patients with and without axial-joint inflammation by MRI, although it had poor accuracy (area under the curve, 0.63; 95% confident interval, 0.53-0.72; P = 0.01).

CONCLUSIONS

Based on our results, MRI could be used to supplement traditional disease assessment tools for more accurate disease evaluation.