THE ETIOLOGY OF PLEURAL EFFUSIONS IN AN AREA WITH HIGH-INCIDENCE OF TUBERCULOSIS

To investigate the etiology of pleural effusions in our region, we und ertook a prospective study of patients with this condition in our cent ers. During a 5-year period, we studied 642 pleural effusion patients aged 57.1+/-21.1 years, of whom 401 were men aged 56.5+/-21 years and 241 were women aged 57.8+/-21.4 years; the male/female ratio was 1.6:1 , The most frequent cause of pleural effusion was tuberculosis (25%), followed by neoplasia (22.9%) and congestive heart failure (17.9%). Th e etiology of 48 cases (7.5%) remained uncertain. In the neoplastic ef fusion group, the most frequent locations of the primary tumor were lu ng (32.6%), breast (11.5%), lymphoma (10.8%), and ovary (7.5%); in 21 cases (14.3% of the neoplastic group), it was not possible to identify the primary tumor, The 111 patients aged younger than 40 years with t uberculous effusions made up 69.4% of tuberculous effusion cases and t he same percentage of patients younger than 40 years; the proportion o f effusions that were tuberculous peaked in the 11- to 30-year-old age group and declined steadily thereafter, Of the patients with neoplast ic effusions, 83% were older than 50 years; the proportion of effusion s that were neoplastic rose steadily from zero in the 0- to 30-year-ol d age group to a peak among 60- to 70-year-olds, The age-wise distribu tion of effusions secondary to congestive heart failure was similar to that of neoplastic effusions, Of the effusions secondary to congestiv e heart failure, 86% (99/115) affected the right pleura or both, and 8 3% of effusions secondary to pulmonary thromboembolism (15/18) affecte d the right side, Neoplastic, tuberculous, parapneumonic, empyematous, and other exudative effusions showed no preference for either side, O f the 97 bilateral effusions, 77 (79.4%) were secondary to heart failu re (59, 60.8%) or neoplasia (18, 18.6%), We conclude that in our regio n, the most frequent cause of pleural effusion is tuberculosis, follow ed by neoplasia and congestive heart failure. We suggest that all thos e interested in pleural disease should determine the etiologic pattern of pleural effusion in their region with a view to the adoption of re gionally optimized diagnostic and therapeutic attitudes.