McMaster University, Hamilton, Ontario, Canada.
Ann Intern Med. 2013 Jan 15;158(2):93-100. doi: 10.7326/0003-4819-158-2-201301150-00003.
D-Dimer testing is sensitive but not specific for diagnosing deep venous thrombosis (DVT). Changing the use of testing and the threshold level for a positive test result on the basis of risk for DVT might improve the tradeoff between sensitivity and specificity and reduce the need for testing.
To determine whether using a selective D-dimer testing strategy based on clinical pretest probability (C-PTP) for DVT is safe and reduces diagnostic testing compared with using a single D-dimer threshold for all patients.
Randomized, multicenter, controlled trial. Patients were allocated using a central automated system. Ultrasonographers and study adjudicators but not other study personnel were blinded to trial allocation. (ClinicalTrials.gov: NCT00157677)
5 Canadian hospitals.
Consecutive symptomatic patients with a first episode of suspected DVT.
Selective testing (n = 860), defined as D-dimer testing for outpatients with low or moderate C-PTP (DVT excluded at D-dimer levels <1.0 µg/mL [low C-PTP] or <0.5 µg/mL [moderate C-PTP]) and venous ultrasonography without D-dimer testing for outpatients with high C-PTP and inpatients, or uniform testing (n = 863), defined as D-dimer testing for all participants (DVT excluded at D-dimer levels <0.5 µg/mL).
The proportion of patients not diagnosed with DVT during initial testing who had symptomatic venous thromboembolism during 3-month follow-up and the proportion of patients undergoing D-dimer testing and ultrasonography.
The incidence of symptomatic venous thromboembolism at 3 months was 0.5% in both study groups (difference, 0.0 percentage point [95% CI, -0.8 to 0.8 percentage points]). Selective testing reduced the proportion of patients who required D-dimer testing by 21.8 percentage points (CI, 19.1 to 24.8 percentage points). It reduced the proportion who required ultrasonography by 7.6 percentage points (CI, 2.9 to 12.2 percentage points) overall and by 21.0 percentage points (CI, 14.2 to 27.6 percentage points) in outpatients with low C-PTP.
Results may not be generalizable to all D-dimer assays or patients with previous DVT, study personnel were not blinded, and the trial was stopped prematurely.
A selective D-dimer testing strategy seems as safe as and more efficient than having everyone undergo D-dimer testing when diagnosing a first episode of suspected DVT.
Heart and Stroke Foundation of Ontario.
D-二聚体检测具有较高的敏感性，但特异性较低，因此无法用于诊断深静脉血栓形成（DVT）。根据 DVT 的风险改变检测的使用和阳性检测结果的阈值，可能会提高敏感性和特异性之间的权衡，并减少检测的需求。
确定基于 DVT 的临床预测概率（C-PTP）的选择性 D-二聚体检测策略是否安全，与对所有患者使用单一 D-二聚体阈值相比，是否可以减少诊断性检测。
随机、多中心、对照试验。患者使用中央自动化系统进行分配。超声医师和研究裁决者（但不是其他研究人员）对试验分配进行盲法评估。（ClinicalTrials.gov：NCT00157677）
加拿大 5 家医院。
疑似首次 DVT 发作的连续症状患者。
选择性检测（n = 860），定义为 C-PTP 较低的门诊患者（D-二聚体水平＜1.0 µg/mL[低 C-PTP]或＜0.5 µg/mL[中 C-PTP]）进行 D-二聚体检测，C-PTP 较高的门诊患者和住院患者进行静脉超声检查但不进行 D-二聚体检测，或常规检测（n = 863），定义为所有患者进行 D-二聚体检测（D-二聚体水平＜0.5 µg/mL 可排除 DVT）。
初始检测未诊断为 DVT 的患者在 3 个月随访期间出现症状性静脉血栓栓塞的比例，以及进行 D-二聚体检测和超声检查的患者比例。
两组的 3 个月症状性静脉血栓栓塞发生率均为 0.5%（差异，0.0 个百分点[95%CI，-0.8 至 0.8 个百分点]）。选择性检测使需要进行 D-二聚体检测的患者比例降低了 21.8 个百分点（CI，19.1 至 24.8 个百分点）。它使所有患者的超声检查比例降低了 7.6 个百分点（CI，2.9 至 12.2 个百分点），使低 C-PTP 的门诊患者的超声检查比例降低了 21.0 个百分点（CI，14.2 至 27.6 个百分点）。
结果可能不适用于所有 D-二聚体检测方法或既往有 DVT 的患者，研究人员未进行盲法评估，并且试验提前终止。
在诊断疑似首次 DVT 时，与对所有人进行 D-二聚体检测相比，使用选择性 D-二聚体检测策略似乎同样安全且更有效。
安大略省心脏和中风基金会。
