Patient records were anonymized and de-identified prior to analysis.Īctive TB was defined as follows: (1) culture-positive for mycobacteria (2) the presence of caseating granulomas, together with a positive TB polymerase chain reaction (PCR) in tissue specimens obtained by biopsy or surgery or (3) a positive MTB PCR in sputum, bronchial washing, or abscess aspiration samples. The Institutional Review Board (IRB) of Seoul National University Bundang Hospital, South Korea, and the IRB of Seoul National University Hospital, South Korea, approved the study protocol and waived the need for informed consent because no patients were at risk. ![]() In this study, the electronic medical records of patients who were evaluated by an IGRA and were finally diagnosed with active pulmonary or extrapulmonary TB at Seoul National University Hospital or Seoul National University Bundang Hospital from February 2008 to December 2013 were retrospectively analyzed. In this study, we aimed to investigate the impact of patient age on the sensitivity of the two commercial IGRAs. Most of these studies were performed with QTF-GIT alone, and the study results were contradictory. However, relatively few studies have examined the influence of age on IGRAs. ![]() There is concern that this decline of immune responsiveness may decrease the sensitivity of IGRAs in aged populations. Since aging leads to a decline in the strength of immune responses, older individuals tend to be more susceptible to TB. TB method uses separate mixtures of ESAT-6 and CFP-10 synthetic peptides as Mycobacterium tuberculosis-specific antigens, whereas QFT-GIT uses a single mixture of synthetic ESAT-6, CFP-10, and TB7.7 peptides. TB measures the number of IFN-γ-secreting T cells via an enzyme-linked immunospot (ELISPOT) assay. QFT-GIT measures the concentration of interferon-gamma (IFN-γ) via an enzyme-linked immunosorbent assay (ELISA), whereas T-SPOT. ![]() Both tests are approved by the Food and Drug Administration as indirect tests for TB infection (including active disease) when used in combination with other medical and diagnostic evaluations. There are currently two types of commercial IGRAs available, the QuantiFERON-TB Gold In-Tube test (QFT-GIT) and the T-SPOT. The interferon-gamma release assay (IGRA) was recently developed to overcome the limitations of the TST, and it is expected to be more useful for the diagnosis of TB infection. However, it has a high false positive rate in patients who were vaccinated with bacille de Calmette-Guerin (BCG) or were infected with nontuberculous mycobacteria. The tuberculin skin test (TST) has been conventionally used as the standard diagnostic test for TB infection. TB is a very prevalent infectious disease, and early and accurate diagnosis is essential to control its spread. TB, was significantly affected by patient age.Īlthough the incidence of and mortality due to tuberculosis (TB) is slowly decreasing worldwide, in 2013, approximately 9.0 million new cases of TB were reported, and annually, there are approximately 1.5 million deaths due to TB infection worldwide. However, only QFT-GIT was significantly related to age in the multivariate analysis. The trend of age-related changes in sensitivity was significant for both QFT-GIT ( p = 0.004) and T.SPOT. ![]() TB according to age group were as follows: 70 years, 68.3% and 85.7%, respectively. The overall sensitivity was 80.2% for QFT-GIT and 91.0% for T.SPOT. Of the patients with pulmonary TB, 76 (39.6%) were in the QFT-GIT group and 143 (67.5%) in the T-SPOT. The QFT-GIT group included 192 TB patients, and the T-SPOT. The positivity of the two tests was analyzed and compared with true TB infection, which was defined as active TB based on either a positive Mycobacterium culture or a positive TB polymerase chain reaction. We retrospectively reviewed the medical records of diagnosed TB patients who were tested using either QFT-GIT or T-SPOT. Owing to contradictory reports regarding whether the results of these IGRAs are affected by the age of the patient, we aimed to determine if these two tests have age-related differences in sensitivity. Currently, there are two types of interferon-gamma release assays (IGRAs) in use for the detection of tuberculosis (TB) infection, the QuantiFERON-TB Gold In-Tube test (GFT-GIT) and T-SPOT.
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