A prospective longitudinal study evaluating a T-cell-based assay for latent tuberculosis infection in health-care workers in a general hospital in Beijing

摘要

Background The health-care workers (HCWs) are at high risk of acquiring infection with Mycobacterium tuberculosis.The objectives of this study were to compare the performance of the T-SPOT.TB and tuberculin skin test (TST) for latent tuberculosis infection (LTBI),evaluate diagnostic concordance and risk factors for LTBI,and observe the progression to active tuberculosis (TB) disease among HCWs in a general hospital in Beijing.Methods The prospective cohort study enrolled HCWs in a tertiary general hospital in Beijing,China,to evaluate LTBI with T-SPOT.TB and TST.The subjects were evaluated every 12 months during the 60-month follow-up.Results Of 101 participating HCWs,96 and 101 had valid TST and T-SPOT.TB results,respectively.Twenty-nine (28.7％,95％ confidence interval (CI),19.9％-37.5％) were defined as positive by T-SPOT.TB and 53 (55.2％,95％ CI,45.2％-64.9％) were defined as positive by TST (using a ≥10 mm cutoff).An agreement between the two tests was poor (57.3％,K=0.18,95％ CI,0.01％-0.52％).In multivariate analysis,direct exposure to sputum smear-positive TB patients was a significant risk factor for a positive T-SPOT.TB (OR 5.76; 95％ CI 1.38-24.00).Pooled frequency of antigenspecific IFN-γ secreting T-cells for subjects who reported direct contact with sputum smear-positive TB patients was significantly higher than that for participants without direct contact (P=-0.045).One of 20 participants with positive result of T-SPOT.TB and TST developed active TB at 24-month follow-up.Conclusion T-SPOT.TB is a more accurate,targeted method of diagnosing LTBI than TST.