RESUMEN
There have been no systematic studies of diseases causing pleural effusion in Qatar. This prospective, hospital-based study involved all adult patients [> 15 years] with pleural effusions who were admitted to referral hospitals over a 1-year period. A total of 200 cases of pleural effusion were identified [152 males and 48 females]; mean age 45.1 [SD 18.5] years. A majority of patients [73.5%] were non-Qataris, mostly from the Asian subcontinent. The most frequent cause of pleural effusions was tuberculosis [32.5%], followed by pneumonia [19%], cancer [15.5%] and cardiac failure [13%]. The most frequent cause of malignant effusion was bronchogenic carcinoma [38.7%], whereas Gram-positive organisms were the most frequent isolates from empyema fluid [62.5%]. Histological examination and culture of pleural biopsy were the most useful diagnostic workup for tuberculosis effusions, whereas repeated cytological examination of pleural fluid and pleural biopsy were most useful for malignant effusions