Early spondyloarthropathy: scintigraphic, biological, and clinical findings in MRI-positive patients

There are no specific diagnostic tests or a gold standard method for measuring disease activity and outcome in spondyloarthropathies (SpA). Many different methods have been developed to assess the signs and symptoms in SpA. The aim of this study was to evaluate the value of scintigraphy, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and Bath Ankilosing Spondylitis Disease Activity Index (BASDAI) in the evaluation of disease activity in early axial SpA diagnosed with magnetic resonance imaging (MRI). Thirty early MRI-positive axial SpA patients (23 males, 7 females) with a median age of 35 (18–55) years and a median duration of inflammatory low back pain of 24 (8–60) months were included in the study. In the patients with sacroiliitis, the sensitivity, specificity, and positive and negative predictive values of disease activity parameters were determined regarding MRI as the gold standard method. The sensitivities of quantitative scintigraphy, visual scintigraphy, ESR, CRP, and BASDAI were 32, 82, 35, 71, and 60%, respectively. The specificities of quantitative scintigraphy, ESR, CRP, and BASDAI were 100, 100, 50, and 100%, respectively. The positive predictive values of quantitative scintigraphy, visual scintigraphy, ESR, CRP, and BASDAI were 100, 92, 100, 95, and 100%, respectively. The negative predictive values of quantitative scintigraphy, ESR, CRP, and BASDAI were 9, 10, 11, and 15%, respectively. Regarding MRI as the gold standard in the evaluation of disease activity, combined visual and quantitative bone scintigraphy can be valuable in patients with MRI-incompatible implants. Additionally, use of cheaper, simple, and readily reproducible tests such as CRP and BASDAI together could be valuable and practical in detecting disease activity in long-term follow-up of these patients.