Emergency Department, Ospedale Guglielmo da Saliceto, Piacenza, Italy
Emergency Department, San Raffaele Hospital, Milano, Italy.
Emerg Med J. 2022 Dec;39(12):941-944. doi: 10.1136/emermed-2020-210688. Epub 2021 Sep 7.
Diagnosis of venous thromboembolism (VTE) requires chest CT angiography for pulmonary embolism and venous ultrasound for deep vein thrombosis. To reduce imaging, guidelines recommend D-dimer levels to rule-out VTE in patients with a low pre-test probability. The most widely used D-dimer cut-off is 500 ng/mL. This cut-off has low specificity, meaning many patients without disease require imaging.
In this retrospective chart review, we evaluated the diagnostic performance of the D-dimer/fibrinogen ratio (DFR) for identifying thromboembolism and compared it to the performance of two different D-dimer cut-offs (500 ng/mL and 1000 ng/mL) in patients who underwent a chest CT angiography or a venous ultrasound in the ED of San Raffaele Hospital, Italy, in 2017. Patients had a retrospective Wells score calculated after chart review, identifying both high-risk and low-risk pre-test probability patients for this study and low probability patients were further stratified into low-risk of deep vein thrombosis or pulmonary embolism.
Enrolled patients included 92 with suspected pulmonary embolism and 154 with suspected deep vein thrombosis; of whom 67 (27%) were diagnosed with VTE. The most accurate cut-off for DFR in terms of discriminative power was 2.65. In the whole sample and in low-risk patients, this cut-off had the same sensitivity values of the 500 ng/mL D-dimer cut-off (97% (95% CI: 89.8% to 99.2%)), while slightly lower sensitivity values were found for the 1000 ng/mL D-dimer cut-off (95.5% (95% CI: 87.6% to 98.5%)). Specificity was higher for the 2.65 DFR cut-off (55.3% (95% CI: 48.0% to 62.4%)) in the whole sample compared with both 500 ng/mL D-dimer cut-off (22.9% (95% CI: 17.4% to 29.6%)) and 1000 ng/mL D-dimer cut-off (45.8% (95% CI: 38.7% to 53.1%)). Similar results were found in all subgroups.
A DFR, with a cut-off of 2.65, may improve the specificity for VTE patients when compared with D-dimer alone in high-risk VTE emergency medicine populations. This is exploratory information only, needing evaluation in prospective, multicentre studies, prior to consideration for use in routine clinical work.
静脉血栓栓塞症（VTE）的诊断需要进行肺动脉 CT 血管造影以排除肺栓塞，同时需要进行下肢静脉超声以排除深静脉血栓形成。为了减少影像学检查，指南建议使用 D-二聚体水平来排除低预测试验概率患者的 VTE。最常用的 D-二聚体截断值为 500ng/ml。然而，该截断值的特异性较低，意味着许多没有疾病的患者需要进行影像学检查。
在这项回顾性图表审查中，我们评估了 D-二聚体/纤维蛋白原比值（DFR）在识别血栓栓塞方面的诊断性能，并将其与两种不同的 D-二聚体截断值（500ng/ml 和 1000ng/ml）在意大利圣拉斐尔医院急诊科接受胸部 CT 血管造影或下肢静脉超声检查的患者中的表现进行了比较。在图表审查后计算了每位患者的回顾性 Wells 评分，确定了本研究中高风险和低风险预测试验概率患者，并对低概率患者进行了进一步分层，分为深静脉血栓形成或肺栓塞的低风险患者。
纳入的患者中，92 例疑似肺栓塞，154 例疑似深静脉血栓形成；其中 67 例（27%）被诊断为 VTE。在区分能力方面，DFR 的最佳截断值为 2.65。在整个样本中以及低风险患者中，该截断值与 500ng/ml D-二聚体截断值（97%（95%CI：89.8%至 99.2%））具有相同的敏感性，而与 1000ng/ml D-二聚体截断值（95.5%（95%CI：87.6%至 98.5%））相比，敏感性略低。与 500ng/ml D-二聚体截断值（22.9%（95%CI：17.4%至 29.6%））和 1000ng/ml D-二聚体截断值（45.8%（95%CI：38.7%至 53.1%））相比，2.65 DFR 截断值在整个样本中的特异性更高（55.3%（95%CI：48.0%至 62.4%））。在所有亚组中均观察到了类似的结果。
与单独使用 D-二聚体相比，高风险 VTE 急诊医学人群中，DFR 截断值为 2.65 可能会提高 VTE 患者的特异性。这只是探索性信息，需要在前瞻性、多中心研究中进行评估，然后才能考虑在常规临床工作中使用。
