AB094. SOH24AB_170. A meta-analysis of the diagnostic accuracy of Hounsfield units on computed tomography relative to dual-energy X-ray absorptiometry for the diagnosis of osteoporosis in the spine surgery population

Background: Preoperative identification of osteoporosis (OP) in spine surgery patients is of crucial importance. Limitations, such as access and reliability, are associated with dual-energy X-ray absorptiometry (DXA). The Hounsfield unit (HU), a readily available measure on computed tomography (CT), is a potential diagnostic tool for reduced bone mineral density (BMD). However, the optimal threshold settings for diagnosing OP are undetermined. Methods: Selected studies included comparison of HU (index test) with DXA (reference test). Data quality was assessed using Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 criteria. Studies were characterised based on the threshold of the index test used, with the goal of obtaining a high sensitivity, high specificity or balanced sensitivity-specificity test. Results: Nine studies were included. In the high specificity group, pooled sensitivity was 0.652 [95% confidence interval (CI): 0.526–0.760], specificity was 0.795 (95% CI: 0.711–0.859) and diagnostic odds ratio was 6.652 (95% CI: 4.367–10.133). In the high sensitivity group, overall pooled sensitivity was 0.912 (95% CI: 0.718–0.977), specificity was 0.67 (95% CI: 0.57–0.75) and diagnostic odds ratio was 19.424 (95% CI: 5.446–69.275). In the balanced sensitivity-specificity group, overall pooled sensitivity was 0.625 (95% CI: 0.504–0.732), specificity was 0.914 (95% CI: 0.823–0.960) and diagnostic odds ratio was 14.880 (95% CI: 7.521–29.440). Considerable heterogeneity existed throughout. Conclusions: HU is a clinically useful tool to diagnose OP. However, the heterogeneity in this study warrants caution in the interpretation of results. Differing HU threshold values impact the diagnostic ability of this test. We would propose a threshold of 150 HU to differentiate between normal and low BMD, and a value of 110 HU to indicate OP.