QuantiFERON-TB Gold and the TST are both useful for latent tuberculosis infection screening in autoimmune diseases

Screening for active tuberculosis (TB) and latent TB infection (LTBI) is mandatory prior to the initiation of tumour necrosis factor-alpha inhibitor therapy. However, no agreement exists on the best strategy for detecting LTBI in this population. The aim of the present study was to analyse the performance of the tuberculin skin test (TST) and QuantiFERON (R)-TB Gold in-tube (QFT-GIT) on LTBI detection in subjects with immunomediated inflammatory diseases (IMID). The TST and QFT-GIT were prospectively performed in 398 consecutive IMID subjects, 310 (78%) on immunosuppressive therapy and only 16 (4%) had been bacillus Calmette-Guerin (BCG) vaccinated. Indeterminate results to QFT-GIT were found in five (1.2%) subjects. Overall, 74 (19%) out of 393 subjects were TST-positive and 52 (13%) were QFT-GIT-positive. Concordance between TST and QFT-GIT results was good (87.7%): 13 were QFT-GIT-positive/TST-negative and 35 QFT-GIT-negative/TST-positive. By multivariate analysis both tests were significantly associated with older age. Only the TST was associated with BCG vaccination and radiological lesions of past TB. Use of immunosuppressive drugs differently modulated QFT-GIT or TST scoring. Use of the QuantiFERON (R)-TB Gold in-tube, as a screening tool for latent tuberculosis among immunomediated inflammatory disease subjects, is feasible. Until further data will elucidate discordant tuberculin skin test/QuantiFERON (R)-TB Gold in-tube results, a strategy of simultaneous tuberculin skin and QuantiFERON (R)-TB Gold in-tube testing in a low prevalence bacillus Calmette-Guerin vaccinated population, should maximise potentials of latent tuberculosis diagnosis.