Quantitative analysis of tuberculin skin test (TST) and interferon gamma release assay (IGRA) results among four groups of contacts exposed to a patient with pulmonary tuberculosis: 1) TST- = contacts who have TST<10mm at baseline and 6 weeks; 2) TSTc = contacts who undergo TST conversion at 6 weeks (see definition in <i>Methods</i>); 3) TST+/IGRA- = contacts with TST ≥10mm at baseline and IGRA-; and 4) TST+/IGRA+ = contacts with TST ≥10mm at baseline and IGRA+.

<p>Circles indicate baseline values and triangles indicate values at 6 weeks. The solid horizontal bars indicate the median value. The N for each group is the same for TST and IGRA results.