Incidence and predictors of acute pulmonary embolism in patients with cancer referred for computed tomography pulmonary angiography

Pulmonary embolism (PE) is a significant cause of morbidity and mortality in cancer patients, yet its clinical presentation is often nonspecific, leading to potential overuse of CT pulmonary angiography (CTPA). This study aimed to determine the incidence of acute PE in a cohort of cancer patients referred for CTPA at a tertiary care cancer centre and to identify clinical and radiological risk factors that predict its presence. We conducted a retrospective observational study of 369 consecutive cancer patients who underwent CTPA for suspected PE between January 2015 and May 2019. Clinical, laboratory, and imaging data were collected from electronic medical records. CTPA scans were reviewed for the presence of acute PE and alternative diagnoses. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of PE. The negative predictive value of D-dimer was also assessed. The incidence of acute PE was 21.4% (79/369 patients; 95% CI: 17.2-25.6%). In patients without PE, disease progression (39%) and pulmonary infection (20%) were the most common alternative diagnoses. Significant independent predictors for PE included the presence of unilateral limb edema (OR = 5.236, p = .005), adenocarcinoma histology (OR = 1.986, p = .034), inpatient status (OR = 2.775, p = .037), and echocardiographic findings suggestive of right ventricular strain (OR = 4.157, p = .001). The negative predictive value of a D-dimer level > 500 ng/dl was 90.5%. Nearly one in five cancer patients with clinically suspected PE had a positive CTPA. Unilateral limb edema, inpatient status, adenocarcinoma histology, and signs of right heart strain on ECHO are significant predictors. These factors can aid in risk stratification, potentially refining the diagnostic pathway for PE in this high-risk population.