AB1025 TRABECULAR BONE SCORE IN PATIENTS WITH AXIAL-SPONDYLOARTHRITIS

Abstract

BackgroundIn axial spondyloarthritis, the bone mineral density (BMD) is usually overestimated due to syndesmophytes. Hence, the trabecular bone score (TBS) could be suggested as a complementary tool that provides additional information on bone microarchitecture (1).ObjectivesThe aim of this study was to explore the trabecular bone score (TBS) association with disease parameters and vertebral fractures in axial spondyloarthritis.MethodsWe designed a cross-sectional study of patients with axial spondyloarthritis diagnosed according to the ASAS 2009 classification, recruited from December 1st, 2021. SA patients excluded were those with a history of cancer, hyperparathyroidism, hyperthyroidism, chronic kidney disease, cirrhosis, and those using osteoporosis and steroid drugs or having a body mass index (BMI) of more than 36kg/m 2. BMD (of lumbar, hip, femoral neck, 33% distal radius of non-dominant hand) and TBS were measured with Dual-energy X-ray absorptiometry (DXA). Vertebral fractures (VF) were assessed by vertebral fracture assessment (VFA). They were defined as grade 2 or 3 according to Genant criteria. Clinical data and laboratory tests collected simultaneously with the DXA scan were analyzed. The associations between TBS and disease parameters: Ankylosing Spondylitis Disease Activity Score (ASDAS), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Metrology Index (BASMI), and the Modified stoke ankylosing spondylitis spinal score (mSASSS) were studied by correlations and multiple linear regressions using SPSS 20.ResultsForty-three patients were included with a mean age of 36.42 ± 13.10 years and a mean disease duration of 12.88 ± 7.69 years. The mean TBS was 1.370 ± 0.098 and the mean lumbar BMD was 0.937 ± 0.210. The mean TBS was significantly lower in patients with comorbidities (high blood pressure and diabetes). TBS was also positively associated with lumbar BMD (r = 0.386; p = 0.011), hip BMD (r = 0.621; p < 0.001), but not forearm BMD (r = 0.276; p = 0.073). Moreover, TBS was negatively associated with age (r = - 0.525; p < 0.001), BMI (r = - 0.440; p = 0.001), and waist circumference (r = - 0.558; p < 0.001). TBS was also negatively correlated with the ASDAS score (r = - 0.378; p = 0.014), while there was no correlation with the BASDAI, BASMI, BASFI, and mSASSS. The association of TBS and ASDAS CRP was significant at adjustment on disease duration and mSASSS (p = 0.017; β = - 0.363; [- 0.056; - 0.006]). However, there was no association between TBS and VF.ConclusionIn SA patients, TBS was negatively associated with disease activity score and positively associated with axial bone loss. This result may explain bone fragility in active spondyloarthritis. No clear association was found between TBS and VF in the present study.