Table 2.
Frequency of Test Result Combinations
| Test Combination (TST-QFT-TSPOTa) | Count (N = 1510) | % |
|---|---|---|
| Triple negative (---) | 1355 | 89.7 |
| Isolated QFT positive (-+-) | 58 | 3.8 |
| Isolated TST positive (+--) | 46 | 3.0 |
| Triple positive (+++) | 23 | 1.5 |
| QFT positive and TSPOT positive (-++) | 12 | 0.8 |
| TST positive and QFT positive (++-) | 12 | 0.8 |
| Isolated TSPOT positive (--+) | 4 | 0.3 |
| TST positive and TSPOT positive (+-+) | 0 | 0.0 |
Abbreviations: QFT, QuantiFERON Gold In-Tube; TSPOT, T-SPOT.TB; TST, tuberculin skin test.
aWe used the CDC guidelines for the interpretation of TST results (≥5 mm positive) and the manufacturer’s US cutoffs for QFT (≥0.35 IU/mL) and TSPOT (≥8 spots positive). Borderline TSPOT was treated as negative.