Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA, USA.
J Bone Miner Res. 2012 Apr;27(4):808-16. doi: 10.1002/jbmr.1539.
Vertebral strength, as estimated by finite element analysis of computed tomography (CT) scans, has not yet been compared against areal bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) for prospectively assessing the risk of new clinical vertebral fractures. To do so, we conducted a case-cohort analysis of 306 men aged 65 years and older, which included 63 men who developed new clinically-identified vertebral fractures and 243 men who did not, all observed over an average of 6.5 years. Nonlinear finite element analysis was performed on the baseline CT scans, blinded to fracture status, to estimate L1 vertebral compressive strength and a load-to-strength ratio. Volumetric BMD by quantitative CT and areal BMD by DXA were also evaluated. We found that, for the risk of new clinical vertebral fracture, the age-adjusted hazard ratio per standard deviation change for areal BMD (3.2; 95% confidence interval [CI], 2.0-5.2) was significantly lower (p < 0.005) than for strength (7.2; 95% CI, 3.6-14.1), numerically lower than for volumetric BMD (5.7; 95% CI, 3.1-10.3), and similar for the load-to-strength ratio (3.0; 95% CI, 2.1-4.3). After also adjusting for race, body mass index (BMI), clinical center, and areal BMD, all these hazard ratios remained highly statistically significant, particularly those for strength (8.5; 95% CI, 3.6-20.1) and volumetric BMD (9.4; 95% CI, 4.1-21.6). The area-under-the-curve for areal BMD (AUC = 0.76) was significantly lower than for strength (AUC = 0.83, p = 0.02), volumetric BMD (AUC = 0.82, p = 0.05), and the load-to-strength ratio (AUC = 0.82, p = 0.05). We conclude that, compared to areal BMD by DXA, vertebral compressive strength and volumetric BMD consistently improved vertebral fracture risk assessment in this cohort of elderly men.
基于 CT 扫描的有限元分析（FEA）评估的椎体强度，尚未通过双能 X 射线吸收法（DXA）与面积骨密度（BMD）进行对比，以前瞻性评估新发临床椎体骨折的风险。为此，我们对 306 名年龄在 65 岁及以上的男性进行了病例队列分析，其中 63 名男性发生了新的临床确诊的椎体骨折，243 名男性未发生，所有患者的平均观察时间为 6.5 年。对基线 CT 扫描进行了非线性有限元分析，分析结果对骨折状态进行了盲法评估，以估计 L1 椎体压缩强度和负荷-强度比。还评估了定量 CT 的体积 BMD 和 DXA 的面积 BMD。我们发现，对于新发临床椎体骨折的风险，DXA 评估的面积 BMD 每标准差变化的年龄校正风险比（HR）为 3.2（95%置信区间 [CI]，2.0-5.2），显著低于强度（7.2；95%CI，3.6-14.1），低于体积 BMD（5.7；95%CI，3.1-10.3），与负荷-强度比（3.0；95%CI，2.1-4.3）相似。在校正种族、体重指数（BMI）、临床中心和面积 BMD 后，所有这些 HR 仍然具有统计学意义，尤其是强度（8.5；95%CI，3.6-20.1）和体积 BMD（9.4；95%CI，4.1-21.6）的 HR。面积 BMD 的曲线下面积（AUC）为 0.76，显著低于强度（AUC=0.83，p=0.02）、体积 BMD（AUC=0.82，p=0.05）和负荷-强度比（AUC=0.82，p=0.05）。我们得出的结论是，与 DXA 的面积 BMD 相比，在这个老年男性队列中，椎体压缩强度和体积 BMD 一致改善了椎体骨折风险评估。
