血浆D 二聚体临界值联合Wells量表对可疑肺栓塞的除外价值

目的：评价传统和按年龄校正的血浆D 二聚体临界值分别联合二分类Wells量表对可疑肺栓塞的除外价值。方法：入选北京大学人民医院2013年9月至2015年1月因胸痛、呼吸困难等症状怀疑肺栓塞的患者335例，其中复选年龄>50岁的患者274例；应用二分类Wells量表进行临床肺栓塞可能性评估，选择Wells量表评分≤4分患者，分别联合血浆D-二聚体传统临界值（500 μg/L）和按年龄校正的临界值（年龄>50岁患者为:年龄×10 μg/L），以CT肺动脉造影为确诊肺栓塞的金标准，比较两种临界值对可疑肺栓塞的除外价值。结果：（1）传统和按年龄校正的血浆D-二聚体临界值分别联合二分类Wells量表诊断肺栓塞的ROC曲线下面积为0.764（95%CI：0.703~0.818）和0.814（95%CI：0.756~0.863），差异无统计学意义（Z=0.05，P =0.121）；（2）传统血浆D-二聚体临界值联合二分类Wells量表诊断肺栓塞的敏感性、特异性、阳性预测值、阴性预测值、约登指数分别为100%、48.9%、28.8%、100%，0.49；按年龄校正的血浆D-二聚体临界值联合二分类Wells量表诊断肺栓塞的敏感性、特异性、阳性预测值、阴性预测值、约登指数分别为97.4%、62.3%、35.5%、99.1%，0.60。与传统临界值相比，按年龄校正的血浆D-二聚体临界值联合二分类Wells量表，诊断肺栓塞的特异性（传统临界值组48.9%，年龄校正临界值组62.3%）明显提高，敏感性（传统临界值组100%，年龄校正临界值组99.1%）无明显降低；（3）222例二分类Wells量表评分≤4分患者中，90例（40.5%）患者血浆D 二聚体<传统临界值（500 μg/L），25例（11.3%）患者血浆D-二聚体介于传统临界值（500 μg/L）与年龄校正临界值（年龄×10 μg/L）之间。结论：应用按年龄校正的血浆D-二聚体临界值联合二分类Wells量表可提高50岁以上肺栓塞患者诊断的特异性，未明显降低敏感性，可用于可疑肺栓塞的排除诊断。

Diagnostic value of D-dimer combined with Wells score for suspected pulmonary embolism

Objective： To evaluate the value of conventional and age-adjusted D-dimer cut-off value combined with 2-level Wells score for diagnosis of suspected pulmonary embolism. Methods: In the stu-dy, 335 patients with suspected pulmonary embolism who visited Peking University People’s Hospital were enrolled retrospectively, then 274 patients with age over fifty years were chosen. The 2-level Wells score was applied to evaluate the clinical probability of pulmonary embolism, the diagnostic value of traditional D-dimer cut-off value (500 μg/L) and age adjusted D-dimer cut-off value (age×10 μg/L above 50 years) combined with Wells score no greater than 4 were compared. Computed tomography pulmonary arteriography (CTPA) was considered as the gold standard for diagnosis of pulmonary embolism. Results: (1)The area under a receiver operating characteristic (ROC) curve (AUC) in analysis of the combination of Wells score no greater than 4 and traditional D-dimer cut-off value was 0.764(95%CI：0.703-0.818). On the other hand, the AUC in a ROC analysisof the combination of Wells Score no greater than 4 and age-adjusted D-dimer cut-off value was 0.814(95%CI：0.756-0.863).These two results did not differ statistically(Z=0.05，P =0.121). (2) The sensitivity, specificity, positive predictive value, negative predictive value and Youden index of the diagnosis of pulmonary embolism of the combination of traditional D-dimer cut-off value and 2-level Wells Score were 100%, 48.9%, 28.8%, 100%, and 0.49, respectively. Meanwhile, the sensitivity, specificity, positive predictive value, negative predictive value and Youden index of the diagnosis of pulmonary embolism of the combination of age-adjusted D dimer cut-off value and 2-level Wells Score were 97.4%, 62.3%, 35.5% 99.1%, and 0.60, respectively. Compared with using traditional D-dimer cut-off value, using age-adjusted D-dimer cut-off value could improve the diagnosis specificity (traditional D-dimer cut-off value group: 48.9%, age-adjusted D-dimer cut-off value group: 62.3%) of pulmonary embolism without reducing the sensitivity (traditional D-dimer cut-off value group: 100%, age-adjusted D-dimer cut-off value group: 99.1%). (3) Among the 222 patients with Wells Score no greater than 4, 90 patients were with D-dimer less than traditional cut-off value (500 μg/L), and 25 patients (account for 11.3% of all 222 patients) were with D-dimer between traditional cut-off value and age-adjusted cut-off value. Conclusion: The application of age-adjusted D-dimer cut-off value can improve the diagnostic specificity of pulmonary embolism in patients over 50 years, without reducing the sensitivity. It can be used for ruling out suspected pulmonary embolism safely.