A Comparative study between the two interferon gamma releasing assays in the diagnosis of pulmonary tuberculosis

Z. Al- Ghreer, Asmaa; A. Abdualla, Zainalabdeen

	A Comparative study between the two interferon gamma releasing assays in the diagnosis of pulmonary tuberculosis
Tikrit Journal of Pure Science
Article 1, Volume 21, Issue 3, 2016, Pages 1-6
Authors
Asmaa Z. Al- Ghreer; Zainalabdeen A. Abdualla
Abstract
Objectives: To examine and compare the diagnostic value of Interferon gamma releasing assay (IGRAs) (T- SPOT TB and Qunati FERON Gold in Tube) in the diagnosis of pulmonary tuberculosis. Materials and methods: The study included 40 patients with active pulmonary tuberculosis. They were attendance of Respiratory Health Care Centers in Mosul City for the period from March to December 2013. From each patient a sputum sample was collected and processed for culture on Löwenstein-Jensen (L-J media). Twelve milliliters (ml) of blood from each patients was collected (10 ml collected in heparinised tube for T SPOT TB and 2 ml in QFT-GIT special tubes) Results: From the total 40 patients with positive AFB staining 37 (92.5%) were culture positive. The specificity of both IGRAs were 100% . The sensitivity of T- SPOT TB test was 91.89%, while the QFT-GIT sensitivity was 86.49%. The positive predictive value of both IGRAs was 100%. The negative predictive value of T SPOT TB was 50 %, while that of QFT-GIT was 37.5 %. There was a moderate degree of agreement between the T -SPOT TB and QFT–GIT in (82.5%, k=0.54, 95%CI). The results of the two IGRAs are not affected by BCG vaccination status of TB patients. Conclusions: The IGRAs could provide a supplementary information as part of diagnostic work-up for tuberculosis diagnosis but it is important to note that a negative IGRA does not rule out active TB . Moreover, and of the two IGRAs, QFT GIT is more convenient to adopted for diagnostic use.
Keywords
tuberculosis; SPOT TB; Quanti FERON Gold in tube

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