Pulmonary Embolism Accurately Predicted by Clinical Model

A software algorithm model based on clinical symptoms, signs, and electrocardiogram (ECG) interpretation can accurately predict pulmonary embolism (PE).

Researchers at the University of Florence (Florence, Italy) generated the model by analyzing data from 1,100 patients with suspected PE, including 440 patients who had subsequently confirmed cases based on angiography or autopsy findings. The model was then validated in a separate cohort of 400 patients with suspected PE, of whom 71% were inpatients. The validation sample found that 165 (41%) of the 400 patients had PE, which was confirmed by angiography.

The researchers identified a total of 16 variables, of which 10 (older age, male sex, prolonged immobilization, history of deep vein thrombosis, sudden-onset dyspnea, chest pain, syncope, hemoptysis, unilateral leg swelling, ECG signs of acute cor-pulmonale) were positively associated with PE, and six (prior cardiovascular or pulmonary disease, orthopnea, high fever, wheezes, or crackles on chest auscultation) were negatively associated with PE. The prevalence of PE was then calculated in four probability categories. When the researchers' model indicated a slight, moderate, substantial, or high probability of pulmonary embolism, the true rates were 2%, 28%, 67%, and 94%, respectively. There was no significant difference between inpatients and outpatients with respect to the prevalence of pulmonary embolism. The study was published in the August 1, 2008, issue of in the American Journal of Respiratory and Critical Care Medicine.

"The model proposed may provide physicians with a diagnostic edge when evaluating patients for suspected pulmonary embolism,” concluded lead author Massimo Miniati, M.D., and colleagues. "Even though its predictive accuracy is supported by internal and external validation procedures, further validation in patients from other centers would be desirable.”

Pulmonary embolism is a blockage of the pulmonary artery or one of its branches, usually occurring when a blood clot becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. Symptoms may include difficulty breathing, chest pain during breathing, and in more severe cases, collapse, circulatory instability, and sudden death. Treatment is usually with anticoagulant medication, such as heparin and warfarin, and in severe cases, thrombolysis or surgery.

Related Links:
University of Florence