Quantiferon Gold Test (QFT) Versus Tuberculin Skin Test (TST) in Idiopathic Pleural Effusion

In the present series idiopathic pleural effusion is an entity where no etiology was disclosed for the presence of fluid in the pleural sac, by the usual standard approach, and investigations, short of closed pleural biopsy or video-assisted thoracoscopy which were considered either blind in the first, or rather invasive in the second and hence not applicable in most of our local Egyptian centers. The etiology in such cases, used to be considered tuberculous, until otherwise proved, on the assumption that tuberculin skin test (T.S.T.), was positive. This fact is currently vitiated by the Compulsory BCG Vaccination, in early infancy according to our local official regulations. The recent introduction of Quantiferon Gold blood test (QFT) overcame this obstacle, because its positivity is not affected by previous BCG Vaccination and hence is helpful in the diagnostic etiology of latent tuberculosis. The present study compares both T.S.T. and QFT, in such idiopathic pleural effusion cases. Their incidence, in the present series, reached 31.9%, among a total of 97 examined pleural effusion patients. The results refer to a statistically significant superiority of QFT over T.ST. in this respect; figures being 70.9% and 51.6% respectively (Tables 2,4). More details are shown in Tables (5,6). This superiority was irrespective of presence or absence BCG Vaccination Scar (Tables 8,9). It is suggested, in our circumstances, in such idiopathic cases, to do T.S.T. first, and if inconclusive, to resort to QFT, to disclose a tuberculous etiology for the occurrence of effusion. It is also suggested, for future study, to apply QFT to the pleural fluid itself, rather than the blood, before resorting to more invasive procedures, like thoracoscopy or less informative steps, as blind closed pleural biopsies