DUETS to Characterize Pleural Effusion

Background: Fifty years since its inception, Light’s criteria have been routinely applied in the evaluation of pleural effusions, classifying them as exudates if 1 or more of 3 criteria are met. Advances in thoracic ultrasound (US) technology and easier accessibility, have led to point of care use as a non-invasive technique to evaluate pleural effusions when pleural procedures are contemplated. Objectives: We aimed to develop a score that combined radiological and US features of pleural effusion that could reliably identify an exudate without paired pleural fluid and serum testing thereby leading to cost-savings.Methods: A prospective review of consecutive patients with pleural effusions that necessitated thoracocentesis at a tertiary center was performed. CXR was evaluated to determine unilateral or bilateral involvement followed by US for features of internal echogenicity, pleural nodularity, pleural thickening, and septations. Pleural effusions were classified by Light’s criteria, and albumin gradient in discordant cases. A score combining radiological and US features was developed with the study set. Results: Included were 185 patients with pleural effusions requiring thoracocentesis. Mean age was 64 years, 51% were females. Twenty-nine (16%) were transudates and 156 (84%) were exudates. US features of echogenicity, septations, pleural nodularity and thickening as well as CXR evaluation if the pleural effusion was unilateral or bilateral were combined to create a composite score. A score of less than 2 indicated low likelihood while 2 and above demonstrated high likelihood for exudate. DUETS (Diaphragmatic nodularity, Unilateral, Echogenicity, pleural Thickening, Septations) demonstrated 100% sensitivity and 100% specificity for exudate.Conclusion: DUETS is a radiological US composite score that reliably discriminates exudates from transudate thereby negating the need for paired blood and pleural fluid investigations necessary for Light criteria. DUETS can lead to cost-savings, and future trials to validate the score are eagerly awaited.Funding: No funding was received for this study. Declaration of Interests: The authors have no conflicts of interests to declare.Ethics Approval: All patients provided written consent and the study protocol was approved by Institutional ethics review board at National University Hospital in Singapore (2019/00826).