Wells P S, Anderson D R, Rodger M, Ginsberg J S, Kearon C, Gent M, Turpie A G, Bormanis J, Weitz J, Chamberlain M, Bowie D, Barnes D, Hirsh J
Department of Medicine, University of Ottawa, Ontario, Canada.
Thromb Haemost. 2000 Mar;83(3):416-20.
We have previously demonstrated that a clinical model can be safely used in a management strategy in patients with suspected pulmonary embolism (PE). We sought to simplify the clinical model and determine a scoring system, that when combined with D-dimer results, would safely exclude PE without the need for other tests, in a large proportion of patients. We used a randomly selected sample of 80% of the patients that participated in a prospective cohort study of patients with suspected PE to perform a logistic regression analysis on 40 clinical variables to create a simple clinical prediction rule. Cut points on the new rule were determined to create two scoring systems. In the first scoring system patients were classified as having low, moderate and high probability of PE with the proportions being similar to those determined in our original study. The second system was designed to create two categories, PE likely and unlikely. The goal in the latter was that PE unlikely patients with a negative D-dimer result would have PE in less than 2% of cases. The proportion of patients with PE in each category was determined overall and according to a positive or negative SimpliRED D-dimer result. After these determinations we applied the models to the remaining 20% of patients as a validation of the results. The following seven variables and assigned scores (in brackets) were included in the clinical prediction rule: Clinical symptoms of DVT (3.0), no alternative diagnosis (3.0), heart rate >100 (1.5), immobilization or surgery in the previous four weeks (1.5), previous DVT/PE (1.5), hemoptysis (1.0) and malignancy (1.0). Patients were considered low probability if the score was <2.0, moderate of the score was 2.0 to 6.0 and high if the score was over 6.0. Pulmonary embolism unlikely was assigned to patients with scores < or =4.0 and PE likely if the score was >4.0. 7.8% of patients with scores of less than or equal to 4 had PE but if the D-dimer was negative in these patients the rate of PE was only 2.2% (95% CI = 1.0% to 4.0%) in the derivation set and 1.7% in the validation set. Importantly this combination occurred in 46% of our study patients. A score of <2.0 and a negative D-dimer results in a PE rate of 1.5% (95% CI = 0.4% to 3.7%) in the derivation set and 2.7% (95% CI = 0.3% to 9.0%) in the validation set and only occurred in 29% of patients. The combination of a score < or =4.0 by our simple clinical prediction rule and a negative SimpliRED D-Dimer result may safely exclude PE in a large proportion of patients with suspected PE.
我们之前已经证明，临床模型可安全用于疑似肺栓塞（PE）患者的管理策略中。我们试图简化该临床模型并确定一个评分系统，该评分系统与D - 二聚体结果相结合时，能够在很大比例的患者中安全地排除PE，而无需进行其他检查。我们使用了参与疑似PE患者前瞻性队列研究的80%患者的随机样本，对40个临床变量进行逻辑回归分析，以创建一个简单的临床预测规则。确定新规则的切点以创建两个评分系统。在第一个评分系统中，患者被分类为PE低、中、高概率，其比例与我们原始研究中确定的比例相似。第二个系统旨在创建两类，即PE可能和PE不太可能。后者的目标是，D - 二聚体结果为阴性的PE不太可能患者中，PE发生的病例不到2%。总体上以及根据SimpliRED D - 二聚体结果为阳性或阴性来确定每个类别中PE患者的比例。在做出这些确定后，我们将模型应用于其余20%的患者以验证结果。临床预测规则包括以下七个变量及分配的分数（括号内）：DVT的临床症状（3.0）、无其他诊断（3.0）、心率>100（1.5）、前四周内制动或手术（1.5）、既往DVT/PE（1.5）、咯血（1.0）和恶性肿瘤（1.0）。如果分数<2.0，则患者被认为是低概率；分数为2.0至6.0为中度；分数超过6.0为高概率。分数<或=4.0的患者被归类为PE不太可能，分数>4.0则为PE可能。分数小于或等于4的患者中有7.8%患有PE，但如果这些患者的D - 二聚体为阴性，在推导集中PE的发生率仅为2.2%（95%CI = 1.0%至4.0%），在验证集中为1.7%。重要的是，这种组合发生在我们研究患者的46%中。分数<2.0且D - 二聚体结果为阴性时，在推导集中PE的发生率为1.5%（95%CI = 0.4%至3.7%），在验证集中为2.7%（95%CI = 0.3%至9.0%），且仅发生在29%的患者中。我们简单的临床预测规则分数<或=4.0与SimpliRED D - 二聚体结果为阴性的组合，可能在很大比例的疑似PE患者中安全地排除PE。
