OC 31.5 - Identifying which emergency department patients should be tested for pulmonary embolism

Background: Pulmonary embolism (PE) can be misdiagnosed wen emergency physicians do not consider PE as a potential diagnosis. Little research has focused on who should be tested for PE.

Aims: To develop a predictive model which identifies underlying PE diagnosis in emergency department patients.

Methods: Using linked population-level administrative data from Ontario (Canada), we analyzed the first patient emergency department visit in each calendar year between 2015 and 2019. Patients were classified as presenting with PE if they were diagnosed with PE on that visit, within the following 30 days if there was no hospitalization, within seven days of hospitalization without surgery, or else prior to surgery within seven days. We collected patient data on age, sex, cancer, prior DVT and PE, pregnancy, coronary artery disease, COPD, diabetes, stroke, anticoagulant use, atrial fibrillation, recent hospitalization, recent surgery, presenting complaint and triage score. Logistic regression and 10-fold cross-validation were used to derive a model which predicts the diagnosis of PE for the year 2015, and subsequently validated the model performance on each calendar year 2016-2019.

Results: We analyzed 7,024,111 emergency department visits with 18751 cases of PE. Mean age 48.6, 52% female, 3% history of cancer, 1.7% stroke, 1% prior PE, 1.6% prior DVT, 1.9% recent admission and 4.4% recent surgery. Our final model predicting a diagnosis of PE contained age, prior PE, prior DVT, presenting complaint and triage category. The area under the curve for the predicting PE was 82.8 in 2015, and 84.5, 81.3, 78.4 and 80.6 for each subsequent year. The optimal cut-off gave sensitivity estimates between 69.4-74.4% and specificity estimates 73.7-76.0% for each of the 5 years.

Conclusion(s): We derived a model which accurately predicts the diagnosis of PE in emergency department patients, with the potential to trigger PE testing in the emergency department.