Objective To compare the consistency of quantitative ultrasound(QUS)and dual-energy X-ray absorptiometry(DXA)in measuring bone mineral density(BMD)of adults aged 18-40 years in Guangzhou and evaluate the diagnostic value of QUS for identifying low bone mass.Methods DXA was employed to measure the BMD and QUS to measure the speed of sound(SOS)in 731 participants.The Bland-Altman analysis was performed to evaluate the consistency of Z scores between SOS and BMD.With the BMD Z ≤-2.00 as the diagnostic criterion for low bone mass,the receiver operating characteristics curve of QUS was established,and the area under the curve(AUC)and the sensitivity,specificity,and correct diagnostic index for the optimal cut-off of SOS Z score were calculated.Results The results of Bland-Altman analysis showed that the mean differences in the Z scores of SOS and BMD in males and females were 1.27(-0.94 to 3.47)and 0.93(-1.33 to 3.18),respectively.The AUC of SOS Z score in the diagnosis of low bone mass in males and females was 0.734(95%CI=0.380-0.788)and 0.679(95%CI=0.625-0.732),respectively.In males,the optimal cut-off of SOS Z score for low bone mass was -0.35,with the sensitivity,specificity,and correct diagnostic index of 64.1%,68.6%,and 0.327,respectively.In females,the optimal cut-off value of SOS Z scores for low bone mass was -1.14,with the sensitivity,specificity,and correct index of 73.9%,54.8%,and 0.285,respectively.Conclusion QUS and DXA show poor consistency in the diagnosis of BMD in the adults aged 18-40 years in Guangzhou,while QUS demonstrates an acceptable value in identifying low bone mass.
目的 比较定量超声测定法(QUS)与双能X线吸收法(DXA)测量广州市18~40岁成人骨密度的一致性,评估QUS识别低骨量的诊断价值。方法 在731名研究对象中,采用DXA测量骨密度(BMD),QUS测量超声传导速度(SOS)。采用Bland-Altman分析评价SOS与BMD Z值的一致性。以BMD Z≤-2.00作为低骨量的诊断标准,绘制QUS的受试者工作特征曲线,并计算曲线下面积(AUC)以及SOS Z值最佳截断值的灵敏度、特异度和正确诊断指数。结果 Bland-Altman分析结果显示,男、女性的SOS和BMD Z值的均值差值分别为1.27(-0.94~3.47)和0.93(-1.33~3.18)。男、女性中SOS Z值诊断低骨量的AUC分别为0.734(95% CI=0.380~0.788)、0.679(95% CI=0.625~0.732)。男性中,低骨量的SOS Z值最佳截断值为-0.35,灵敏度、特异度和正确诊断指数分别为64.1%、68.6%和0.327;女性中,低骨量的SOS Z值最佳截断值为-1.14,灵敏度、特异度和正确诊断指数分别为73.9%、54.8%和0.285。结论 广州市18~40岁成人中,QUS与DXA诊断骨密度的一致性欠佳,但QUS在识别低骨量上的应用价值尚可。.
Keywords: bone mineral density; dual-energy X-ray absorptiometry; low bone mass; quantitative ultrasound; speed of sound.