A simplified clinical model to predict pulmonary embolism in patients with acute dyspnea

The objective of the present study was to develop a simple clinical model for predicting pulmonary embolism (PE) in patients with acute dyspnea in the emergency room.

We enrolled 56 patients diagnosed with PE, and 92 consecutive patients without PE, all of whom presented with acute dyspnea in the emergency room. Primary emergency-room physicians assessed the initial evaluation and interpretation of various laboratory findings. Some significantly independent predictors of PE were identified and integrated into a clinical model of pretest probability: low (< 30%), intermediate (>or= 30%, 70%). After setting up the model, another 40 patients (16 with PE, 24 without PE) were tested using the pretest model. Clinical variables associated with an increased likelihood of PE were being female and having unilateral low-leg edema, a high alveolar-arterial oxygen gradient, a clear chest x-ray, and electrocardiographic findings of right ventricular strain. Variables associated with a decreased likelihood of PE were cough, chest tightness, and unclear breath sounds. Our clinical model predicted that 95% of patients with PE had a high or low probability of PE. The positive predictive value for high probability was 94.1% and the negative predictive value for low probability was 94.4%. In the tested group, the positive predictive value for high probability was 92.9%. The negative predictive value for low probability was 91.3%. This simple and easily available prediction model was useful for estimating the pretest probability of PE in patients with acute dyspnea.