FRI0489 THE ASSOCIATION BETWEEN CT-MEASURED BONE ATTENUATION AND PREVALENT VERTEBRAL FRACTURES IN THE THORACIC SPINE DIFFERS ACCORDING TO VERTEBRAL FRACTURE LOCATIONS
Authors: Mayke J van Dort, Annemariek Driessen, Joop van den Bergh, Emiel Fm Wouters, Elisabeth AM Romme, Frank Wjm Smeenk, Bert van Rietbergen, Piet Geusens
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Subjects with prevalent vertebral fractures (VFs) have lower bone mineral density (BMD) in the lumbar spine and hip than subjects without prevalent VFs. However, VFs are not equally distributed across the thoracic spine. They occur preferentially at T7-T8 and T11-T12, which are the highest loaded vertebral regions during daily activities (1). <h3>Objectives</h3> We evaluated the association of BMD with prevalent VFs at non-preferential locations (nprVFs: T4-T6 and T9-T10) and at preferential locations (prVFs: T7-T8 and T11-T12). <h3>Methods</h3> Baseline CT images of T4-T12 in smokers with and without COPD were analysed for the presence of VFs according to Genant. Bone attenuation (BA), expressed in Hounsfield units (HU), was measured in all non-fractured vertebrae. Linear regression was used to compare mean BA and logistic regression was used to estimate the association between BA and prevalent VFs. All analyses were adjusted for age and sex. <h3>Results</h3> Prevalent VFs were most frequently located at T7-T8 (in &gt;6% of vertebrae) and T11-T12 (in &gt;4% of vertebrae). At subject level and compared to subjects without prevalent VFs, mean BA of all non-fractured vertebrae was significantly lower in subjects with any prevalent VFs (-21%, p&lt;0.0001). There was a significant progressive trend (p&lt;0.0001) in decrease in mean BA of all non-fractured vertebrae between subjects with only prVFs (-15%), with only nprVFs (-25%, p&lt;0.05 vs prVFs) and with both nprVFs and prVFs combined (-32%, p&lt;0.0001 vs prVFs) (all p&lt;0.0001 compared to subjects without VF). At each individual non-fractured vertebral level, each BA decrease of 50 HU was associated with a 2.0-2.5 increased odds of any prevalent VF, a 1.5-1.9 increased odds of only prVF, a 2.2-3.4 increased odds of only nprVF and a 3.8-4.6 increased odds of nprVF and prVF combined. <h3>Conclusion</h3> In addition to BA, other factors such as vertebral load during daily activities may determine the location of a VF. The location of a VF may be a potential <i>in vivo</i> marker of the load/strength ratio of bone. <h3>References</h3> [1] Bruno AG, Burkhart K, Allaire B, Anderson DE, Bouxsein ML. Spinal Loading Patterns From Biomechanical Modeling Explain the High Incidence of Vertebral Fractures in the Thoracolumbar Region. J Bone Miner Res. 2017Jun;32(6):1282-1290 <h3>Disclosure of Interests</h3> Mayke J van Dort: None declared, Annemariek Driessen: None declared, Joop van den bergh Grant/research support from: Grants/research support from Eli Lily, Sanofi, Amgen., Emiel FM Wouters: None declared, Elisabeth AM Romme: None declared, Frank WJM Smeenk: None declared, Bert van Rietbergen: None declared, Piet Geusens Grant/research support from: Research support, consultant and/or speaker fees from: Pfizer, Abbott, Eli Lilly, Amgen, MSD, Roche, UCB, BMS, Novartis, Will-Pharma, Grant/research support from: Pfizer, Abbott, Lilly, Amgen, MSD, Will, Bio Minerals and Roche, Consultant for: Research support, consultant and/or speaker fees from: Pfizer, Abbott, Eli Lilly, Amgen, MSD, Roche, UCB, BMS, Novartis, Will-Pharma, Speakers bureau: Research support, consultant and/or speaker fees from: Pfizer, Abbott, Eli Lilly, Amgen, MSD, Roche, UCB, BMS, Novartis, Will-Pharma, Speakers bureau: Pfizer, Abbott, Lilly, Amgen, MSD, Will, Bio Minerals and Roche