Aetiology, management and outcomes of eosinophilic pleural effusion: data from the International Multicentre Pleural Research Collaborative.

BackgroundEosinophilic pleural effusion (EPE) is a relatively uncommon condition. The objective of this study was to evaluate the clinical, laboratory and radiological features of EPE in a multicentre cohort of patients.MethodsThis retrospective study included patients with EPE, defined as pleural fluid in which eosinophils constitute ≥10% of the total nucleated cell count, treated between 2009 and 2021 at eight respiratory centres. Predefined data were collected in the International Multicentre Pleural Research Collaborative (IMPACT) registry.ResultsThe study included 210 patients (144 (68.6%) males), with a median age of 67 years (interquartile range (IQR) 55-78 years). Radiological evaluation showed unilateral effusion in 194 (94.2%) patients. Most EPEs (199; 95.7%) were exudates. The median pleural fluid eosinophil percentage was 23% (IQR 14.8-43.3%). The most common aetiologies were malignancy (n=61, 29%), infection (n=43, 20.5%), heart diseases/cardiac intervention (n=17, 8.1%) or trauma (n=16, 7.6%). In 42 (20%) patients, the cause of EPE remained undetermined. In univariate and multivariable analyses incorporating available clinical and laboratory data, EPE was not a significant predictor of either malignancy or benign disease.ConclusionEPE is a nonspecific diagnostic entity and should not, by itself, be regarded as a relevant factor in clinical decision-making.