Chan Wee-Shian, Lee Agnes, Spencer Frederick A, Crowther Mark, Rodger Marc, Ramsay Tim, Ginsberg Jeffrey S
Department of Medicine, Women's College Hospital, Toronto, Ontario, Canada.
Ann Intern Med. 2009 Jul 21;151(2):85-92. doi: 10.7326/0003-4819-151-2-200907210-00004.
Clinicians' assessment of pretest probability, based on subjective criteria or prediction rules, is central to the diagnosis of deep venous thrombosis (DVT). Pretest probability assessment for DVT diagnosis has never been evaluated in pregnant women.
To evaluate the accuracy of clinicians' subjective assessment of pretest probability for DVT diagnosis and identify prediction variables that could be used for pretest probability assessment in pregnant women with suspected DVT.
A cross-sectional study conducted over 7 years (March 2000 to April 2007).
5 university-affiliated, tertiary care centers in Canada.
194 unselected pregnant women with suspected first DVT.
Diagnosis of DVT was established with abnormal compression ultrasonography at presentation or on serial imaging. Pretest probability by subjective assessment was recorded by thrombosis experts for each patient before knowledge of results.
The sensitivity, specificity, negative predictive value, and likelihood ratios of subjective pretest probability assessment and their corresponding 95% CIs were calculated on the basis of the diagnosis of DVT. Patients were DVT positive if they had diagnostic compression ultrasonography at initial or serial testing or symptomatic venous thromboembolism on follow-up. Patients were DVT negative if they had negative compression ultrasonography at presentation and no venous thromboembolism on follow-up. A prediction rule for assessing DVT was derived, and an internal validation study was done to explore its performance.
The prevalence of DVT was 8.8%. Clinicians' subjective assessment of pretest probability categorized patients into 2 groups: low pretest probability (two thirds of patients) with a low prevalence of DVT (1.5% [95% CI, 0.4% to 5.4%]) and a negative predictive value of 98.5% (CI, 94.6% to 99.6%), and nonlow pretest probability with a higher prevalence of DVT (24.6% [CI, 15.5% to 36.7%]). Three variables (symptoms in the left leg [L], calf circumference difference > or = 2 cm [E], and first trimester presentation [Ft]) were highly predictive of DVT in pregnant patients.
Few outcomes occurred. Altogether, 17 events were diagnosed during the study. The prediction rule derived should be validated on an independent sample before applying it to clinical practice.
Subjective assessment of pretest probability seems to exclude DVT when the pretest probability is low. Moreover, 3 objective variables ("LEFt") may improve the accuracy of the diagnosis of DVT in pregnancy. Prospective validation studies are needed.
Heart and Stroke Foundation of Ontario.
临床医生基于主观标准或预测规则对检验前概率进行评估，这对深静脉血栓形成（DVT）的诊断至关重要。DVT诊断的检验前概率评估从未在孕妇中进行过评估。
评估临床医生对DVT诊断的检验前概率主观评估的准确性，并确定可用于疑似DVT孕妇检验前概率评估的预测变量。
一项为期7年（2000年3月至2007年4月）的横断面研究。
加拿大5家大学附属的三级医疗中心。
194例未经过筛选的疑似首次发生DVT的孕妇。
通过就诊时或系列影像学检查中异常的加压超声检查确诊DVT。血栓形成专家在知晓结果前为每位患者记录主观评估的检验前概率。
根据DVT诊断计算主观检验前概率评估的敏感性、特异性、阴性预测值和似然比及其相应的95%置信区间。如果患者在初次或系列检查时有诊断性加压超声检查结果，或随访时有症状性静脉血栓栓塞，则判定为DVT阳性。如果患者就诊时加压超声检查结果为阴性且随访时无静脉血栓栓塞，则判定为DVT阴性。推导了评估DVT的预测规则，并进行了内部验证研究以探讨其性能。
DVT的患病率为8.8%。临床医生对检验前概率的主观评估将患者分为两组：检验前概率低（三分之二的患者），DVT患病率低（1.5%[95%置信区间，0.4%至5.4%]），阴性预测值为98.5%（置信区间，94.6%至99.6%）；检验前概率不低，DVT患病率较高（24.6%[置信区间，15.5%至36.7%]）。三个变量（左腿症状[L]、小腿周径差≥2 cm[E]和孕早期就诊[Ft]）对孕妇DVT具有高度预测性。
发生的结果较少。在研究期间共诊断出17例病例。推导的预测规则在应用于临床实践之前应在独立样本上进行验证。
当检验前概率较低时，对检验前概率的主观评估似乎可排除DVT。此外，3个客观变量（“LEFt”）可能提高孕期DVT诊断的准确性。需要进行前瞻性验证研究。
安大略省心脏与中风基金会。
