The relation between elevated D-dimer levels and a positive computed tomography pulmonary angiogram to confirm pulmonary emboli: A retrospective study

Abstract

Introduction: Pulmonary embolism (PE) is one of the most common heart and blood vessel diseases in the world, and can have life-threatening complications. Acute PE is a leading cause of hemodynamic instability and mortality and is the third most common cardiovascular condition after coronary artery disease and stroke. Therefore, timeous diagnosis and proper treatment of PE are imperative to manage this life-threatening condition. PE is diagnosed using laboratory tests and imaging procedures, of which computed tomography pulmonary angiography (CTPA) is the ‘gold standard’. One of the most important laboratory tests is the assessment of D-dimer levels in the blood. Patients with elevated D-dimer levels are routinely referred for CTPA to rule out PE; however, PE is not always confirmed in these referred patients. Consequently, growing evidence suggests overuse of CTPA, which increases the risk of radiation dose and adverse effects from contrast media administration. Aim: This retrospective South African study was conducted in a single private radiology practice in Bloemfontein to determine the relation between an elevated D-dimer level and a positive CTPA, using the picture archiving and communication system (PACS) of patient information. Methods: The data of 1 219 patients, which included 158 COVID-19 referrals, were recorded using a predesigned data capturing instrument. The data variables included biographical information, clinical indicators, and imaging condition values. Results: Overall, the number of patients in the sample population (n = 1 219) with a positive diagnosis of PE was relatively small, at only 16.7%. Of these patients, approximately 50% had elevated D-dimer levels, which was also true for the subpopulation excluding COVID-19 referral patients. In contrast, a few patients (less than 20%) of the subgroup with elevated D-dimer levels had a positive diagnosis of PE. These results show that, although approximately half the patients diagnosed with PE had elevated D-dimer levels, only a few patients with elevated D-dimer levels were diagnosed with PE. This necessitates further investigation into the required routine best practices when deciding which patients should be referred for CTPA during the routine PE workup. In particular, clinical decision rules for PE need refining, especially to limit unnecessary CTPA referrals. Conclusion: The findings of this study may result in the revision of PE workups in the private practice and also assist with the development of practice guidelines to ultimately improve the quality of service.