Schott A M, Kassaï Koupaï B, Hans D, Dargent-Molina P, Ecochard R, Bauer D C, Bréart G, Meunier P J
INSERM U 403, Hôpital Edouard Herriot, 5 place d'Arsonval, Cedex 03, 69437, Lyon, France.
Osteoporos Int. 2004 Mar;15(3):196-203. doi: 10.1007/s00198-003-1505-1. Epub 2004 Jan 17.
In a prospective cohort of 7,598 women aged 75 and over, we analyzed the effect of age on the ability of femoral neck bone mineral density (BMD) and of ultrasound (BUA and SOS) of the calcaneus to predict hip fracture. Unadjusted regression analysis showed that the risk of hip fracture was increased 1.7 times for one standard deviation increase in age (3.7 years). Overall, for a decrease of one standard deviation in quantitative bone measures, the risk was significantly increased by 2.2 times for BMD (1.9-2.5), 1.8 for BUA (1.6-2.1), and 1.9 for SOS (1.6-2.2). However the average relative risk associated with a decrease in BMD tends to diminish with advancing age, meaning that a smaller part of the risk is explained by BMD in the very elderly. This is confirmed by the areas under the ROC curves (AUC) of BMD that are significantly better before 80 years (0.75 [0.73-0.76]) than after (0.65 [0.63-0.67] in group 80-84 years and 0.65 [0.61-0.68] in group >/=85). On the other hand, as the absolute risk increases exponentially with age, the number of hip fractures attributable to a low BMD is still important in the very elderly, the risk difference between the lowest and the highest quartile of BMD is 25 hip fractures / 1,000 woman-years in the group >/=85 compared with 16 in the two other groups. Thus, after 80, quantitative assessment of bone may still be of interest for clinical decisions. Compared with quantitative ultrasound parameters, the ability of BMD to predict hip fracture was significantly superior to that of BUA and SOS only before the age of 80 (AUC of BMD 0.75 [0.73-0.76], BUA 0.67 [0.66-0.69], SOS 0.67 [0.65-0.69]). For patients older than 80, we did not observe significant differences in AUC between DXA and QUS to predict hip fracture.
在一项针对75岁及以上7598名女性的前瞻性队列研究中，我们分析了年龄对股骨颈骨密度（BMD）以及跟骨超声（BUA和SOS）预测髋部骨折能力的影响。未经调整的回归分析显示，年龄每增加一个标准差（3.7岁），髋部骨折风险增加1.7倍。总体而言，对于定量骨测量值每降低一个标准差，BMD的风险显著增加2.2倍（1.9 - 2.5），BUA为1.8倍（1.6 - 2.1），SOS为1.9倍（1.6 - 2.2）。然而，与BMD降低相关的平均相对风险往往会随着年龄增长而降低，这意味着在高龄人群中，BMD所解释的风险比例较小。这一点在BMD的ROC曲线下面积（AUC）中得到证实，80岁之前（0.75 [0.73 - 0.76]）显著优于80岁之后（80 - 84岁组为0.65 [0.63 - 0.67]，≥85岁组为0.65 [0.61 - 0.68]）。另一方面，由于绝对风险随年龄呈指数增长，在高龄人群中，低BMD导致的髋部骨折数量仍然可观，BMD最低四分位数与最高四分位数之间的风险差异在≥85岁组为每1000女性年25例髋部骨折，而在其他两组中为16例。因此，80岁之后，骨定量评估对于临床决策可能仍有意义。与定量超声参数相比，BMD预测髋部骨折的能力仅在80岁之前显著优于BUA和SOS（BMD的AUC为0.75 [0.73 - 0.76]，BUA为0.67 [0.66 - 0.69]，SOS为0.67 [0.65 - 0.69]）。对于80岁以上患者，我们未观察到DXA和QUS在预测髋部骨折的AUC方面存在显著差异。
