Etiology and prognostic significance of eosinophilic pleural effusions - A prospective study

Study objective: To determine the diagnostic and prognostic significance of eosinophilic pleural effusions. Design: A prospective cohort study of patients undergoing thoracentesis between September 1990 and September 1995. Setting: A university-affiliated VA Medical Center. Patients: Four hundred seventy-six consecutive patients. Measurements ann results: Eosinophilic pleural effusions were identified in 44 of the 476 patients (9.2%). Malignancy was diagnosed as frequently in eosinophilic as in noneosinophilic effusions (20.5% vs 20.1%). The only diagnoses that were significantly associated with eosinophilic effusions were idiopathic (25% vs 8%; p=0.001) and postthoracic surgery (11% vs 3%; p=0.023), Median survival was 7.7 months for those with a noneosinophilic effusion compared to 16.8 months for those with eosinophilia (p=0.017). This difference in survival persisted after adjustment for age and diagnosis. Conclusions: We conclude that malignancy is as prevalent among eosinophilic as noneosinophilic pleural effusions, However, the survival of patients with pleural fluid eosinophilia may be better than that of patients with noneosinophilic effusions.