Table 2.

Concordance between TST and T-SPOT.TB Results

Characteristics	New TST positives	Previously defined as TST positives	Total
TST positives among exposed (%)	27/155 (17%)	15/155 (10%)	42/155 (27%)
T-SPOT.TB -positives among exposed (%)	3/155 (2%)	2/155 (1%)	5/155 (3%)
T-SPOT.TB -positives among TST positives (%)	3/27 (11%)	2/15 (13%)	5/42 (12%)

Table 2 depicts concordance between tuberculin skin test (TST) and T-SPOT.TB results. Results in absolute numbers (percentages in brackets) from post-exposure screening of 155 health care workers (HCWs) and 48 healthy controls, 2005–2007. During childhood all participants were either BCG-immunized or had a naturally positive TST. The definition of a positive TST (Mantoux) was an increase of ≥ 10 mm, or of ≥ 15 mm if previous TST status was unknown (in concordance with the national guidelines). The exposed HCWs were also tested with T-SPOT.TB, an interferon-gamma release assay (IGRA). Some HCWs had been defined as TST positives during previous post-exposure screenings (15) while others were defined as TST positives during the current study (27).