Evaluation of an interferon gamma assay in the diagnosis of latent tuberculosis infection in patients with rheumatoid arthritis
The tuberculin skin test is not an ideal screening test for the patients with rheumatoid arthritis to identify cases of latent tuberculosis infection (LTBI) prior to the start of treatment with anti-TNFs, as it responds inadequately to late hypersensitivity, which is fundamental for producing a response to the inoculated antigen. Assays based on detection of the production of IFNγ in vitro by mononuclear peripheral cells stimulated by specific antigens are more specific than PPD in detecting LTBI. The aim of this study was to evaluate the performance of T-SPOT.TB in diagnosis of LTBI in patients with rheumatoid arthritis, comparing with the PPD. The specificity of the T-SPOT.TB varied from 87 to 90% and the negative-predictive value (NPV) from 94.4 to 100%. It can be concluded that the T-SPOT.TB showed high specificity and NPV, proving the capability of identifying false-negative cases of PPD, raising the level of safety for the use of anti-TNFs.
KeywordsRheumatoid arthritis Tuberculosis Diagnosis Interferon-gamma assay
- 8.Mantoux C (1908) Intradermo-réaction de la tuberculine. Comptes rendus de l’Académie des sciences, Paris, 147:355-57 apud http://www.whonamedit.com/synd.cfm/2767.html. Accessed 1 Nov 2005
- 9.Alonzo TA, Pepe MS (1998). Assessing the accuracy of a new diagnostic test when a gold standard does not exist. UW Biostatistics Working Paper Series. University of Washington. Paper 156. http://www.bepress.com/cgi/viewcontent.cgi?article=1043&context=uwbiostat (Accessed 13 Jan 2008)
- 11.Dinser R, Fousse M, Sester U et al (2008) Evaluation of latent tuberculosis infection in patients with inflammatory arthropathies before treatment with TNF-α blocking drugs using a novel flow-cytometric interferon-γ release assay. Rheumatology 72:212–218Google Scholar
- 12.Sellam J, Hamdi H, Roy C et al (2007) Comparison of in vitro-specific blood tests with tuberculin skin test for diagnosis of latent tuberculosis before anti-TNF therapy. Ann Rheum Dis published on line first: 24 April 2007. doi: 10.1136/ard.2007.069799
- 18.Al Zaharani K, Al Jahadali H, Menzies D (2000) Does size matter? Utility of size of tuberculin reactions for the diagnosis of mycobacterial disease. Am J Respir Crit Care Med 162:1419–1422Google Scholar