AB0996 Bone mineral density at different sites as a predictor of rib fractures: a case-control study
Authors: H.L. Wu, M. Bukhari
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Rib fractures commonly occur as a result of direct trauma, though pathological causes have also been identified. Literature on the specific risk factors of rib fractures is scarce. There was an American prospective cohort study which highlighted the relationship between risk factors of osteoporosis and rib fractures in older men aged 65 or above.<sup>1</sup> It was observed that the incidence of rib fractures was 3.5/1000 years. Only 3% of rib fractures occurred with absence of trauma. Bone mineral density (BMD) is an important measure for predicting various bone fractures.<sup>2</sup> However, prediction of rib fractures using BMD measurement in different body sites is not reported. <h3>Objectives</h3> To determine if reduction in femoral neck and lumbar spine BMD are predictive of rib fractures. <h3>Methods</h3> Patients referred from primary care to a DEXA scanner in the north west of <sup>England between January 2006</sup> and December 2016 were used in this study. Patients with a history of rib fractures at first scan were matched with controls who did not have any indication for scanning. Cases and controls were matched for age and gender. Differences in BMD at L1-L4 spine and the femoral neck were analysed using two-sample t test. Logistic regression models were fitted to analyse the association between lumbar spine and femoral neck BMD and rib fracture occurrence. The fit of each model was compared using receiver operating characteristic (ROC) curves. <h3>Results</h3> A total of 1554 patients were included in the study (777 cases of rib fractures and 777 controls). Mean age for both cases and controls were 62.5 years (SD 12.0). 605 patients (77.9%) were female in both the case cohort and the controls. The mean T score in the lumbar spine is 1.00 in cases versus 1.10 in controls (diff 0.100 95% CI 0.0488, 0.142 p&lt;0.001). The mean T score in the femoral neck is 0.812 in cases versus 0.935 in controls (diff 0.123 95% CI 0.108, 0.137 p&lt;0.001). The odds of lumbar spine BMD and femoral neck BMD were 0.111 (95% CI 0.0640, 0.194, p&lt;0.001) and 0.00209 (95% CI 0.000903, 0.00485, p&lt;0.001) respectively. The areas under ROC curve (AUC) for lumbar spine BMD and femoral neck BMD were 0.623 and 0.733. <h3>Conclusions</h3> This study demonstrated that reduction in BMD at the lumbar spine and femoral neck positively correlated to the risk of rib fractures. Reduction in femoral neck BMD is a stronger predictor of the two. Prediction of rib fractures could be affected by other factors influencing lumbar spine and femoral neck BMD. Further work in different demographic groups should be done for comparison and analysis. <h3>References</h3> [1] Barrett-Connor, et al. Epidemiology of rib fractures in older men: Osteoporotic Fractures in Men (MrOS) prospective cohort study. BMJ2010; 340:c1069 [2] Dobrzynska, et al. Predictors of fragility humeral fractures: An Observational Study. Ann Rheum Dis2015; 74(Suppl2):763 <h3>Disclosure of Interest</h3> None declared