Avoidable Overuse of Computed Tomography Pulmonary Angiography (CTPA) in Patients with Suspected Acute Pulmonary Thromboembolism (PTE): The Role of Clinical Prediction Rules and D-Dimer Assay

Background: Computed tomography pulmonary angiography (CTPA) is an imaging technique widely used in the diagnosis of acute pulmonary thromboembolism (PTE). Despite its disadvantages and potential risks, the overuse of CTPA has been a growing concern over the past decades. Objectives: The objective of this study was to investigate the rate of avoidable overuse of CTPA in patients with suspected PTE and to identify factors contributing to this overuse. The study aimed to highlight the importance of proper training for physicians in using validated diagnostic algorithms to minimize the overuse of CTPA and improve patient outcomes. Methods: In a cross-sectional study conducted between April 2016 and March 2019 at Shariati Hospital at Tehran University of Medical Sciences (TUMS), 1058 patients underwent CTPA due to suspected PTE. Wells scores were calculated retrospectively for all patients. The study defined avoidable overuse of CTPA as an imaging request without prior D-dimer testing or ignoring a negative D-dimer result in patients with low clinical pre-test probability. Results: Two hundred and seventy-three patients were excluded from the study due to unavailable documentation or pregnancy. Among the included 785 patients, 139 (17.7%) revealed PTE on CTPA. Based on the Wells scores, 480 patients were identified as the “PTE-unlikely” group. In this group, 299 patients (62.3%) underwent CTPA directly despite recommendations to order a D-dimer test first. Of these patients, 281 (94%) cases showed negative results. Moreover, CTPA was performed inappropriately in 52 “PTE-unlikely” cases despite negative D-dimer serum levels, and only one patient was diagnosed with PTE. Conclusions: The study revealed that 44.7% of the CTPA requests for patients with suspected PTE were avoidable, indicating the need for better adherence to current diagnostic guidelines to reduce unnecessary radiologic investigations and improve patient care.