PT - JOURNAL ARTICLE AU - Samuel M. Behar AU - Daniel S. Shin AU - Agnes Maier AU - Jonathan Coblyn AU - Simon Helfgott AU - Michael E. Weinblatt TI - Use of the T-SPOT.<em>TB</em> Assay to Detect Latent Tuberculosis Infection Among Rheumatic Disease Patients on Immunosuppressive Therapy AID - 10.3899/jrheum.080854 DP - 2009 Feb 15 TA - The Journal of Rheumatology PG - jrheum.080854 4099 - http://www.jrheum.org/content/early/2009/02/12/jrheum.080854.short 4100 - http://www.jrheum.org/content/early/2009/02/12/jrheum.080854.full AB - Objective We evaluated the T-SPOT.TB assay to identify latent tuberculosis infection (LTBI) in patients with rheumatic disease receiving immunosuppressive medication including tumor necrosis factor (TNF) antagonists. Methods A total of 200 patients seen in the Arthritis Center at Brigham and Women’s Hospital were enrolled for study. Most patients were US-born women with rheumatoid arthritis. A medical history was obtained using a questionnaire, whole blood was drawn for the T-SPOT.TB assay, and tuberculin skin testing (TST) was performed. Results Both tests were performed on 179 subjects, who had no history of a positive TST. All subjects had a strong response to the T-SPOT.TB test positive control, and there were no indeterminate results. Among these 179 subjects, 2 had a positive TST and 10 had a positive T-SPOT.TB test. No subject was positive for both tests. Patients with a positive T-SPOT.TB test did not have typical risk factors for LTBI based on clinical evaluation. Conclusion The lack of concordance between the TST and the T-SPOT.TB assay may indicate that the immunoassay is more sensitive, particularly in a patient population taking immunosuppressive medications. It is equally likely that the low prevalence of LTBI in this low-risk population led to an increase in the false-positive rate despite the high sensitivity and specificity of the T-SPOT.TB assay. In the context of our patient population, the T-SPOT.TB assay is likely to be most useful in evaluation of patients with a positive TST, since these patients have a higher pretest probability of having LTBI.