Does a Wells score of 6 indicate the need for anticoagulation prior to computed tomography pulmonary angiography (CTPA)?

From the Guidelines

With a Wells score of 6, indicating a high probability of pulmonary embolism (PE), anticoagulation should be initiated before obtaining a CT pulmonary angiogram (CTPA) to reduce the risk of PE-related mortality. The European Society of Cardiology guidelines 1 recommend initiating anticoagulation without delay in patients with high or intermediate clinical probability of PE, while diagnostic workup is in progress.

The recommended anticoagulation regimen includes therapeutic-dose low molecular weight heparin (LMWH) such as enoxaparin 1 mg/kg twice daily or 1.5 mg/kg once daily, or unfractionated heparin with an initial bolus of 80 units/kg followed by an infusion of 18 units/kg/hour, adjusted to maintain an aPTT of 1.5-2.5 times normal 1.

Some key points to consider when initiating anticoagulation include:

• The risk of PE-related mortality outweighs the risk of bleeding in high-probability patients
• Delaying treatment could lead to clinical deterioration
• Anticoagulation should be started immediately unless there are contraindications such as active bleeding or severe thrombocytopenia
• The Wells score of 6 places the patient in a category where the likelihood of PE is approximately 40-60%

It is essential to note that the decision to initiate anticoagulation should be based on the individual patient's risk factors and clinical presentation, and that the guidelines provided by the European Society of Cardiology 1 should be consulted for more detailed information on the diagnosis and management of acute pulmonary embolism.

From the Research

Wells Score and Anticoagulation

• A Wells score of 6 or higher indicates a high pretest probability of pulmonary embolism (PE) 2, 3, 4.
• The American College of Emergency Physicians guidelines recommend more aggressive workup beyond imaging alone in patients with a high pretest probability of PE 2.
• However, the evidence does not directly address whether a Wells score of 6 indicates the need for anticoagulation prior to computed tomography pulmonary angiography (CTPA).

Diagnostic Accuracy of Wells Score

• The Wells score has been shown to be more accurate than the simplified revised Geneva score in patients with a high suspicion of PE 3, 4.
• The area under the curve (AUC) of receiver operating characteristic (ROC) curves for the Wells score was 0.85 (CI: 0.81 to 0.89) and 0.872 (95%CI 0.810 - 0.933) in two separate studies 3, 4.
• The Wells score performed better than the simplified revised Geneva score in patients with a high suspicion of PE (p<0.05) 3.

Clinical Decision Making

• A combination of D-dimer testing and Wells score can be used as a safe base for making clinical decisions on further investigations for patients with intermediate to high risks of PE 5.
• The negative predictive value (NPV) of D-dimer testing was 92% in patients with intermediate to high risks, and the combination of D-dimer testing and Wells score increased the NPV to 94% 5.
• However, the specificity of both tests was low, and D-dimer testing had a higher NPV than Wells score 5.