Nobes Jennifer, Messow Claudia-Martina, Khan Mohammed, Hrobar Petr, Isles Chris
Medical Unit, Dumfries and Galloway Royal Infirmary, Dumfries, UK.
Robertson Centre for Biostatistics, University of Glasgow, Glasgow, UK.
Postgrad Med J. 2017 Jul;93(1101):420-424. doi: 10.1136/postgradmedj-2016-134552. Epub 2016 Dec 9.
Patients in whom a diagnosis of pulmonary embolism (PE) is suspected and whose D-dimers are elevated frequently require CT pulmonary angiogram (CTPA) for diagnosis. Because D-dimer rises with age, an age-adjusted D-dimer threshold may prevent unnecessary radiation exposure from CTPA in older patients.
To determine the efficacy and safety of implementing an age-adjusted D-dimer threshold to exclude PE.
DESIGN, SETTINGS AND PATIENTS: Retrospective comparison of conventional and age-adjusted D-dimer thresholds in 1000 consecutive patients who had both D-dimer and CTPA.
Conventional and age-adjusted D-dimer thresholds for excluding PE were <250 ng/mL and 5× age for patients older than 50 years, respectively. We defined patients as unlikely to have PE using the revised Geneva score (RGS) and two different categories of clinical risk: RGS ≤5 and RGS ≤10.
We diagnosed PE by CTPA in 244 (24.4%) patients. 3/86 patients (3.5%) whose D-dimer was below the conventional threshold of 250 ng/mL had PE (RGS 3, 9 and 14), all of which were judged to be light clot load (group 1). 3/108 patients (2.8%) whose D-dimer lay between 250 ng/mL and the age-adjusted threshold had PE (RGS 6, 8 and 9), all of which were again judged to be light clot load (group 2). 62/108 group 2 patients with RGS ≤5 were considered unlikely to have PE as were 102/108 using the RGS clinical risk category ≤10. None of the 62 patients with RGS ≤5 had PE while 3/102 patients with RGS ≤10 had PE. 236/806 patients (29.3%) whose D-dimer was above the age-adjusted threshold had PE (group 3).
In a consecutive series of 1000 patients, an RGS ≤5 and an age-adjusted D-dimer would have led to 62 fewer CTPA at a cost of no missed PEs.
疑似肺栓塞（PE）且D-二聚体升高的患者常需进行CT肺动脉造影（CTPA）以明确诊断。由于D-二聚体水平随年龄增长而升高，采用年龄校正后的D-二聚体阈值可能避免老年患者因CTPA而受到不必要的辐射暴露。
确定采用年龄校正后的D-二聚体阈值排除PE的有效性和安全性。
设计、场所和患者：对1000例同时进行D-二聚体检测和CTPA的连续患者，回顾性比较传统D-二聚体阈值和年龄校正后的D-二聚体阈值。
排除PE的传统D-二聚体阈值和年龄校正后的D-二聚体阈值分别为<250 ng/mL和5×年龄（适用于年龄大于50岁的患者）。我们使用修订的日内瓦评分（RGS）和两种不同类别的临床风险将患者定义为不太可能患有PE：RGS≤5和RGS≤10。
通过CTPA诊断出244例（24.4%）患者患有PE。D-二聚体低于250 ng/mL传统阈值的86例患者中有3例（3.5%）患有PE（RGS分别为3、9和14），所有这些患者的血栓负荷均被判定为较轻（第1组）。D-二聚体介于250 ng/mL和年龄校正阈值之间的108例患者中有3例（2.8%）患有PE（RGS分别为6、8和9），所有这些患者的血栓负荷再次被判定为较轻（第2组）。第2组中RGS≤5的62例患者和使用RGS临床风险类别≤10的108例患者中的102例被认为不太可能患有PE。RGS≤5的62例患者中无一例患有PE，而RGS≤10的102例患者中有3例患有PE。D-二聚体高于年龄校正阈值的806例患者中有236例（29.3%）患有PE（第3组）。
在连续的1000例患者中，RGS≤5和年龄校正后的D-二聚体可减少62次CTPA检查，且不会漏诊PE。
