Optimizing interpretation of the tuberculin test using an interferon-gamma release assay as a reference standard.

The interferon-gamma release assays have greater specificity than the tuberculin skin test (TST), and at least equal sensitivity. We analyzed the sensitivity and specificity of the TST in immunocompetent children considering QuantiFERON as the referent standard. A TST cut-off point of ≥ 5 mm indicates excellent sensitivity (100%) and specificity (93%) in children without Bacillus Calmette-Guérin. In Bacillus Calmette-Guérin-vaccinated children, the TST cut-off point of ≥ 10 mm had poorer specificity (86%), and a cut-off point of ≥ 15 mm resulted in reduced sensitivity (60%).