Studies comparing ADA and IFN-γ simultaneously in the same set of patients have reported both ADA better than IFN-γ2–7 and IFN-γ better than ADA1,8–9 as diagnostic markers. In fact, a meta-analysis by Greco et al10 regarding the diagnostic accuracy of ADA vs IFN-γ included 31 studies in favor of ADA (total, n = 4,738) and 13 studies in favor of IFN-γ (total, n = 1,189). Using summary receiver operating characteristic curve, they found only a marginal difference in overall sensitivity and specificity: 93% for ADA, and 96% for IFN-γ. Using Bayes theorem, the posttest probability of a negative test result was calculated. The minute difference in posttest probabilities (ADA vs IFN-γ, 0.4% vs 0.22%, 2.4% vs 1.2%, and 24% vs 17%) was maintained over a wide prevalence range of 5 to 85%. The authors concluded that “ADA and IFN-γ appear to be reasonably accurate at detecting TB pleurisy.” Virtually similar sensitivity and specificity coupled with lower cost should favor the use of ADA as a diagnostic tool compared to IFN-γ.