Saturday, November 14, 2015
For example, in patients who have a low pretest probability of PE, the so-called PERC (Pulmonary Embolism Rule-Out Criteria) algorithm should be applied. Those patients who meet all eight PERC items should not undergo either imaging or plasma D-dimer tests.
Instead, the ACP now recommends clinicians should take the following steps, depending on a patient’s pretest probability of PE:
Modified Wells Scoring System
The AAFP/ACP guideline advocates use of the Modified Wells prediction rule for the above-specified estimation and interpretation requirements (see Table 1, below). However, the guideline notes that the Wells rule performs better in younger patients without comorbidities or a history of venous thromboembolism. Current evidence also suggests this tool is effective in pregnant patients.
Moreover, the objective components of the Wells (Canadian Pulmonary Embolism Score) criteria have been shown to have little effect on the stratification power of the criteria; virtually all of the classification power is associated with a physician’s subjective prejudgment of the likelihood of pulmonary embolism.
Table 1. Modified Wells Prediction Rule for Diagnosing Pulmonary Embolism: Clinical Evaluation Table for Predicting Pretest Probability of Pulmonary Embolism* (Open Table in a new window)
|Previous pulmonary embolism or deep vein thrombosis||+ 1.5|
|Heart rate >100 beats per minute||+ 1.5|
|Recent surgery or immobilization (within the last 30 d)||+ 1.5|
|Clinical signs of deep vein thrombosis||+ 3|
|Alternative diagnosis less likely than pulmonary embolism||+ 3|
|Cancer (treated within the last 6 mo)||+ 1|
|Clinical Probability of Pulmonary Embolism||Score|
|*Reprinted from Am J Med, Vol. 113, Chagnon I, Bounameaux H, Aujesky D, et al, Comparison of two clinical prediction rules and implicit assessment among patients with suspected pulmonary embolism, pp 269-75, Copyright 2002.|