Study objectives: Pleural tuberculosis (TB) is a
diagnostic challenge because of its nonspecific clinical presentation
and paucibacillary nature. The inefficiency of conventional laboratory
methods and the reliance on pleural biopsy have motivated the
evaluation of alternative diagnostic strategies. We have evaluated
polymerase chain reaction (PCR) directed to the
IS6110 sequence of Mycobacterium
tuberculosis, the determination of adenosine deaminase (ADA)
activity, and measurement of interferon (IFN)-γ levels in pleural
fluid in the diagnosis of pleural TB.
activity, IFN-γ levels, and PCR were evaluated in 140 cases of
pleural effusion, 42 with confirmed pleural TB, 19 with probable
pleural TB, 70 with a nontuberculous etiology, and 9 having an
Results: ADA activity, IFN-γ
levels, and PCR were 88%, 85.7%, and 73.8% sensitive, respectively,
and 85.7%, 97.1%, and 90% specific, respectively, for pleural TB
that had been confirmed by either culture or pleural biopsy specimens.
The combination of PCR, IFN-γ measurement, and ADA activity
determination allowed the selective increase of sensitivity and
specificity for probable and confirmed cases compared to individual
methods. Positive and negative predictive values for these individual
or combined methods were maintained over a wide range of prevalence of
pleural TB in the patient population presenting with pleural effusions.
Fever and younger age were associated with tuberculous pleural effusion
(p < 0.0001), while blood in sputum and older age were associated
with malignant etiology (p < 0.008).
These clinical variables together with the use of ADA activity
determination, PCR, and measurement of IFN-γ levels provide the basis
for the rapid and efficient diagnosis of pleural TB in different