School of Medicine, Trinity College Dublin, DN, Ireland; National Spinal Injuries Unit, Department of Trauma & Orthopaedic Surgery, Mater Misericordiae University Hospital, DN, Ireland; Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2 D02 R590, Ireland.
Royal College of Surgeons in Ireland, St. Stephen's Green, DN, Ireland.
Spine J. 2021 Oct;21(10):1738-1749. doi: 10.1016/j.spinee.2021.03.008. Epub 2021 Mar 13.
The preoperative identification of osteoporosis in the spine surgery population is of crucial importance. Limitations associated with dual-energy x-ray absorptiometry, such as access and reliability, have prompted the search for alternative methods to diagnose osteoporosis. The Hounsfield Unit(HU), a readily available measure on computed tomography, has garnered considerable attention in recent years as a potential diagnostic tool for reduced bone mineral density. However, the optimal threshold settings for diagnosing osteoporosis have yet to be determined.
We selected studies that included comparison of the HU(index test) with dual-energy x-ray absorptiometry evaluation(reference test). Data quality was assessed using the standardised QUADAS-2 criteria. Studies were characterised into 3 categories, based on the threshold of the index test used with the goal of obtaining a high sensitivity, high specificity or balanced sensitivity-specificity test.
9 studies were eligible for meta-analysis. In the high specificity group, the pooled sensitivity was 0.652 (95% CI 0.526 - 0.760), specificity 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, the overall pooled sensitivity was 0.912 (95% CI 0.718 - 0.977), specificity was 0.67 (0.57 - 0.75) and diagnostic odds ratio was 19.424 (5.446 - 69.275). In the balanced sensitivity-specificity group, the overall pooled sensitivity was 0.625 (95% CI 0.504 - 0.732), specificity was 0.914 (0.823 - 0.960) and diagnostic odds ratio was 14.880 (7.521 - 29.440). Considerable heterogeneity existed throughout the analysis.
In conclusion, the HU is a clinically useful tool to aide in the diagnosis of osteoporosis. However, the heterogeneity seen in this study warrants caution in the interpretation of results. We have demonstrated the impact of differing HU threshold values on the diagnostic ability of this test. We would propose a threshold of 135 HU to diagnose OP. Future work would investigate the optimal HU cut-off to differentiate normal from low bone mineral density.
在脊柱手术患者中，术前识别骨质疏松症至关重要。双能 X 射线吸收法（DXA）存在局限性，例如获取和可靠性问题，这促使人们寻找替代方法来诊断骨质疏松症。Hounsfield 单位（HU）是 CT 上一种易于获取的测量值，近年来作为诊断骨密度降低的潜在工具引起了广泛关注。然而，诊断骨质疏松症的最佳阈值设置仍有待确定。
我们选择了比较 HU（指标测试）与双能 X 射线吸收法评估（参考测试）的研究。使用标准化 QUADAS-2 标准评估数据质量。根据指标测试的阈值，研究分为 3 类，目的是获得高灵敏度、高特异性或平衡灵敏度特异性测试。
9 项研究符合荟萃分析条件。在高特异性组中，汇总灵敏度为 0.652（95%CI 0.526-0.760），特异性为 0.795（95%CI 0.711-0.859），诊断比值比为 6.652（95%CI 4.367-10.133）。在高灵敏度组中，汇总的总体灵敏度为 0.912（95%CI 0.718-0.977），特异性为 0.67（0.57-0.75），诊断比值比为 19.424（5.446-69.275）。在平衡灵敏度特异性组中，汇总的总体灵敏度为 0.625（95%CI 0.504-0.732），特异性为 0.914（0.823-0.960），诊断比值比为 14.880（7.521-29.440）。整个分析过程中存在很大的异质性。
总之，HU 是一种有助于诊断骨质疏松症的临床有用工具。然而，本研究中的异质性表明，在解释结果时需要谨慎。我们已经证明了不同 HU 阈值值对该测试诊断能力的影响。我们建议使用 135 HU 的阈值来诊断 OP。未来的工作将研究区分正常和低骨密度的最佳 HU 截止值。
