DUETS for Light's in separating exudate from transudate

Background Fifty years since its inception, Light's criteria have aided in classifying pleural effusions (PEs) as exudates if 1 or more criteria are met. Thoracic ultrasound (US) emerges as a non‐invasive technique for point of care use especially if pleural procedures are contemplated. Objective We aimed to develop a score based on radiological and US features that could separate exudates from transudates without serum and pleural fluid biochemical tests necessary for Light's criteria. Methods A prospective review of consecutive patients with PE who underwent thoracocentesis was performed. CXRs were evaluated for laterality followed by US for echogenicity, pleural nodularity, thickening and septations. PE was classified as exudate or transudate according to Light's criteria and corroborated with albumin gradient. A score combining radiological and US features was developed. Results We recruited 201 patients with PE requiring thoracocentesis. Mean age was 64 years, 51% were females, 164 (81.6%) were exudates, and 37 (18.4%) were transudates. Assigning 1‐point for Diaphragmatic nodularity, Unilateral, Echogenicity, Pleural Thickening and Septations, DUETS ranged from 1 to 5. DUETS ≥2 indicated high likelihood for exudate (PPV 98.8%, NPV 100%) with 1% misclassification versus 6.9% using Light's criteria (p