Incidence of Pulmonary Embolism in Patients with Positive D-Dimers and Chest X-ray Evidence of Pneumonia: A Retrospective Study

Introduction: Evaluation of chest pain in the Emergency Department is common. Significant resources are expended looking for dangerous etiologies. The D-dimer is frequently utilized but can be positive in a variety of pathologic and non-pathologic states, including pneumonia. We anticipated that patients who had pneumonia on chest x-ray and also a positive D-dimer would have a low likelihood of also having pulmonary embolism. We hoped to define this patient population as low risk of having PE in the setting of pneumonia with the purpose of limiting unnecessary CT angiographies. Methods: We performed a retrospective analysis to identify patients who had an elevated D-dimer, evidence of pneumonia by chest x-ray and who underwent subsequent CT angiography [CTA] or Ventilation/perfusion [V/Q] scanning. We correlated the results of the CTA or V/Q with patient demographics, vital signs, and laboratory values to evaluate our patient population. Results: We identified 151 patients who had an infiltrate on the chest x-ray and elevated d-dimer that subsequently went on to have CTA or V/Q to rule out pulmonary embolism. Of this group of patients 7/151 [4.6%] had a PE. We then performed statistical analysis using the vital signs, lab values, and patient demographics to look for differences between patients with pulmonary embolism and without. However, no statistically significant conclusions could be made. Conclusions: In patients with elevated D-dimer and pneumonia our series demonstrated a small but not uncommon rate of concurrent PE. A larger study group would be required to determine risk stratification of this group.