踝臂指数诊断下肢动脉疾病的敏感性和特异性

The sensitivity and specificity of ankle brachial index in diagnosis of lower extremity arterial disease in the patients with high cardiovascular risk

目的 通过与数宁减影血管造影（DSA）的对比，评价踝臂指数（ABI）诊断下肢动脉疾病的敏感性和特异性；研究ABI存人群筛检时的诊断界值。方法连续选取在上海同济大学和中同医科大学两所附属医院心内科住院患者383例，其中男性245例，女性138例，所有患者均接受DSA榆查及ABI的测量。采用受试者工作特征曲线（ROC）分析曲线下而积和敏感性、特异性及似然比。结果在以DSA显示下肢动脉狭窄≥50％为诊断下肢动脉疾病的金标准时，ABI等于0．95诊断下肢动脉疾病的敏感性为93．0％，特异性为85．0％，阳性似然比为8．81，阴性似然比为0．23。ROC曲线下面积为0．953（95％CI为0．920～0．985）。结论ABI可以代替DSA识别下肢动脉疾病的患者。往我国人群中，可以考虑用ABI等于0．95作为筛检下肢动脉疾病的诊断界点。

Objective To prospectively evaluate the sensitivity and specificity of ankle brachial index （ABI） in the diagnosis of lower extremity arterial disease（LEAD）by using conventional digital subtraction angiography （DSA） as the reference standard, and to research the threshold value of ABI screening test for diagnosis. Methods A total of 383 consecutive patients [245 men and 138 women, mean age （64. 1±11.7） years] underwent conventional DSA and ABI measurement. Receiver operator characteristics （ROC） analysis was performed to assess possible threshold values for predicting the LEAD in these patients. Results Conventional DSA was used as the gold standard in defining ≥50 % luminal stenosis for the diagnosis of LEAD, 0.95 was the overall cutoff of ABI which was associated with 93.0% sensitivity, 85.0% specificity, 8.81 positive likelihood ratio（＋LR） and 0. 23 negative likelihood ratio（LR） for detection of hemodynamically significant stenosis （lesions≥50%） in all 383 subjects （P〈0.01）. The area under the ROC curve was 0.953（95% CI 0.920--0. 985）. Conclusions ABI measurement is an accurate and reliable non invasive alternative to conventional DSA in the diagnosis of lower extremity arterial disease. And the cut-off 0.95 is the threshold ABI value for detecting I.EAD in Chinese population.