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DIAGNOSIS OF LATENT TUBERCULOSIS INFECTION WITH AN INTERFERON-GAMMA RELEASE ASSAY IN IMMUNOSUPPRESSED RHEUMATOLOGY PATIENTS
October 2008, Vol 134, No. 4_MeetingAbstracts Abstract: Poster Presentations | October 2008
DIAGNOSIS OF LATENT TUBERCULOSIS INFECTION WITH AN INTERFERON-GAMMA RELEASE ASSAY IN IMMUNOSUPPRESSED RHEUMATOLOGY PATIENTS P. Escalante, MD; R. Khan, MD*; S. S. Aye, MD; S. Christianakis, MD; D. G. Arkfeld, MD; G. R. Ehresmann, MD; B. E. Jones, MD; J. J. Kort, PhD University of Southern California, Los Angeles, CA Chest Chest. 2008;134(4_MeetingAbstracts):p154003. doi:10.1378/chest.134.4_MeetingAbstracts.p154003
Abstract PURPOSE: The diagnosis of latent tuberculosis infection (LTBI) in immunosuppressed patients is challenging. Studies have shown that interferon-gamma release assays (IGRAs) are more specific and probably more sensitive than the tuberculin skin test (TST). However, there is limited data in rheumatology patients receiving immunosuppressive therapy. METHODS: This is a prospective study conducted at a referral rheumatology clinic. We compared TST and T-SPOT. TBÖ (an IGRA) results, including agreement analysis, in patients receiving immunosuppressive therapy. RESULTS: We studied sixty-nine patients. Fifty-three were from countries where BCG is placed routinely. Fifty-three had rheumatoid arthritis, including ten patients on TNF-alpha antagonists. Eighteen patients were TST positive and fifteen were IGRA positive. Two patients had indeterminate IGRA results. Eight patients were both TST and IGRA positive, and forty-two patients were both TST and IGRA negative (Agreement = 74.6%; kappa = 0.32; P = 0.009). Ten out of the eighteen TST-positives were IGRA negative, and seven out of the fifteen IGRApositives were TST negative (Discordance = 25.3%). Among eighteen non-BCG vaccinated patients, the agreement was 83.3% (kappa = 0.47; P = 0.043). CONCLUSION: There is substantial discordance between T-SPOT. TBÖ and TST results in this patient population, possibly associated with differences in the specificity of both tests in BCG-vaccinated patients. CLINICAL IMPLICATIONS: Some TST results may not be accurate in immunosuppressed rheumatology patients. Longitudinal studies are needed to elucidate the predictive value for LTBI of IGRA testing in this patient population.
DISCLOSURE: R Khan, Other Oxford Immunotec supplied the TSPOT. TB kits.; Product/procedure/technique that is considered research and is NOT yet approved for any purpose. TSPOT. TB is not approved in the USA for the diagnosis of latent tuberculous infection. Wednesday, October 29, 2008 1:00 PM - 2:15 PM
DIAGNOSIS OF LATENT TUBERCULOSIS INFECTION WITH AN INTERFERON-GAMMA RELEASE ASSAY IN IMMUNOSUPPRESSED RHEUMATOLOGY PATIENTS P. Escalante, MD; R. Khan, MD*; S. S. Aye, MD; S. Christianakis, MD; D. G. Arkfeld, MD; G. R. Ehresmann, MD; B. E. Jones, MD; J. J. Kort, PhD University of Southern California, Los Angeles, CA Chest Chest. 2008;134(4_MeetingAbstracts):p154003. doi:10.1378/chest.134.4_MeetingAbstracts.p154003
Abstract PURPOSE: The diagnosis of latent tuberculosis infection (LTBI) in immunosuppressed patients is challenging. Studies have shown that interferon-gamma release assays (IGRAs) are more specific and probably more sensitive than the tuberculin skin test (TST). However, there is limited data in rheumatology patients receiving immunosuppressive therapy. METHODS: This is a prospective study conducted at a referral rheumatology clinic. We compared TST and T-SPOT. TBÖ (an IGRA) results, including agreement analysis, in patients receiving immunosuppressive therapy. RESULTS: We studied sixty-nine patients. Fifty-three were from countries where BCG is placed routinely. Fifty-three had rheumatoid arthritis, including ten patients on TNF-alpha antagonists. Eighteen patients were TST positive and fifteen were IGRA positive. Two patients had indeterminate IGRA results. Eight patients were both TST and IGRA positive, and forty-two patients were both TST and IGRA negative (Agreement = 74.6%; kappa = 0.32; P = 0.009). Ten out of the eighteen TST-positives were IGRA negative, and seven out of the fifteen IGRApositives were TST negative (Discordance = 25.3%). Among eighteen non-BCG vaccinated patients, the agreement was 83.3% (kappa = 0.47; P = 0.043). CONCLUSION: There is substantial discordance between T-SPOT. TBÖ and TST results in this patient population, possibly associated with differences in the specificity of both tests in BCG-vaccinated patients. CLINICAL IMPLICATIONS: Some TST results may not be accurate in immunosuppressed rheumatology patients. Longitudinal studies are needed to elucidate the predictive value for LTBI of IGRA testing in this patient population.
DISCLOSURE: R Khan, Other Oxford Immunotec supplied the TSPOT. TB kits.; Product/procedure/technique that is considered research and is NOT yet approved for any purpose. TSPOT. TB is not approved in the USA for the diagnosis of latent tuberculous infection. Wednesday, October 29, 2008 1:00 PM - 2:15 PM