TY - JOUR T1 - Use of interferon-γ release assays in diagnosis of active TB infection - Experience of a rural UK hospital JF - European Respiratory Journal JO - Eur Respir J VL - 42 IS - Suppl 57 SP - P501 AU - Sam Roberts AU - Janet Anderson AU - Paul Godwin AU - Harold Stephen Ronald Hosker Y1 - 2013/09/01 UR - http://erj.ersjournals.com/content/42/Suppl_57/P501.abstract N2 - Interferon gamma release assays (IGRA’s) can be used as supplementary tests for TB when culture results are unavailable. To assess the efficacy of this approach in our population, we identified all IGRA’s performed in our laboratory and retrospectively examined indication and clinical outcome.Of 899 IGRA's, all were T-SPOT.TB tests performed since September 2006. 377 were part of investigation for suspected active TB. 53 of these patients were subsequently diagnosed with TB based on microbiological evidence and/or clinical suspicion and response to treatment.33 TB patients had a positive T-SPOT, 16 had a negative T-SPOT. Of patients with subsequent microbiological proof of TB, 10 had a positive T-SPOT and 4 had a negative result. T-SPOT sensitivity for pulmonary and nodal TB was 62.5% and 78.6% respectively. Overall sensitivity was 67.3%. Sensitivity in culture proven cases was 71.4%.Of 287 negative T-SPOT’s, 16 patients were subsequently found to have TB giving a negative predictive value of 94.7%.Our results show a lower sensitivity for T-SPOT in diagnosis of active TB than in other work (Dai et al. Eur J Clin Microbiol Infect Dis. 2012 Nov;31(11):3127-37. Goletti et al. PLoS ONE 2008 3(10): e3417). This is likely to reflect test performance in a clinical setting, where testing is performed in cases where cultures are difficult to obtain. In addition, the low prevalence of TB in our cohort compared to others may have reduced sensitivity.We conclude that IGRA testing should be used with caution in diagnosis of active TB in low prevalence population and every effort should be made to obtain culture results. However, the test is of value as a negative predictor for TB. ER -