Incidence rates (IRs//1000 person-years) and predictive values for incident TB from the time of QuantiFERON TB-Gold (QFT) testing, by observation time (</>2 years) and interferon-γ (IFN-γ) category*
| QFT result | n | Years | TB | IR | PPV (hPPV)† | NPV (hNPV)† |
| <2 years after QFT(or until TB, LTBI treatment, death, emigration or study end) | ||||||
| Total study population | 44 875 | 80 270 | 205 | 2.6 | (0.5) | (99.5) |
| Positive, total | 9 878 | 15 802 | 176 | 11.1 | 1.8 | – |
| Low positive | 2166 | 3593 | 14 | 3.9 | 0.6 | – |
| Medium positive | 2670 | 4259 | 38 | 8.9 | 1.4 | – |
| High positive | 5042 | 7950 | 124 | 15.6 | 2.5 | – |
| Negative | 34 128 | 63 064 | 24 | 0.4 | – | 99.9 |
| Inconclusive | 869 | 1404 | 5 | 3.6 | – | – |
| Positive, by age (years) | ||||||
| <5 | 66 | 73 | 3 | 41.2 | 4.5 | – |
| 5–14 | 376 | 396 | 9 | 22.7 | 2.4 | – |
| 15–34 | 5293 | 8371 | 111 | 13.3 | 2.1 | – |
| 35–64 | 3530 | 6011 | 45 | 7.5 | 1.3 | – |
| ≥65 | 613 | 954 | 8 | 8.4 | 1.3 | – |
| Any medical risk factor | 17 101 | 30 734 | 27 | 0.9 | – | – |
| Positive, total | 1376 | 2074 | 18 | 8.7 | 1.3 | – |
| Low positive | 478 | 746 | 2 | 2.3 | 0.4 | – |
| Medium positive | 418 | 611 | 2 | 3.3 | 0.5 | – |
| High positive | 480 | 707 | 14 | 19.8 | 2.9 | – |
| Negative | 15 176 | 27 808 | 7 | 0.3 | – | 99.9 |
| Inconclusive | 549 | 852 | 2 | 2.3 | – | – |
| Foreign-born, total | 19 418 | 34 010 | 183 | 5.4 | (0.9) | (99.1) |
| Positive, total | 8306 | 13 480 | 164 | 12.2 | 2.0 | – |
| Low positive | 1474 | 2497 | 13 | 5.2 | 0.9 | – |
| Medium positive | 2176 | 3553 | 36 | 10.1 | 1.7 | – |
| High positive | 4656 | 7430 | 115 | 15.5 | 2.5 | – |
| Negative | 10 871 | 20 147 | 14 | 0.7 | – | 99.9 |
| Inconclusive | 241 | 382 | 5 | 13.1 | – | – |
| Norwegian-born, total | 25 457 | 46 262 | 22 | .5 | (0.09) | (99.9) |
| Positive, total | 1572 | 2322 | 12 | 5.2 | 0.8 | – |
| Low positive | 692 | 1096 | 1 | 0.9 | 0.1 | – |
| Medium positive | 494 | 706 | 2 | 2.8 | 0.4 | – |
| High positive | 386 | 520 | 9 | 17.3 | 2.3 | – |
| Negative | 23 257 | 42 917 | 10 | 0.2 | – | 99.9 |
| Inconclusive | 628 | 1022 | – | – | – | – |
| ≥2 years after QFT (until TB, LTBI treatment, death, emigration or study end) | ||||||
| Total study population | 39 942 | 88 520 | 52 | 0.6 | (0.1) | (99.9) |
| Positive, total | 7132 | 17 041 | 43 | 2,5 | 0.6 | – |
| Low positive | 1679 | 4095 | 3 | 0.7 | 0.2 | – |
| Medium positive | 1910 | 4703 | 8 | 1.7 | 0.4 | – |
| High positive | 3543 | 8243 | 32 | 3.9 | 0.9 | – |
| Negative | 32 124 | 70 123 | 9 | 0.1 | – | 99.9 |
| Inconclusive | 686 | 1356 | – | – | – | – |
*Low positive, IFN-γ 0.35 to <1.0; medium positive, IFN-γ 1.0 to <4.0; and high positive, IFN-γ>4.0 IU/mL.
†For a hypothetical test in which all individuals tested positive (for hPPV) or all tested negative (for hNPV).
hNPV, hypothetical negative predictive value; hPPV, hypothetical positive predictive value; LTBI, latent TB infection; Years, sum of person-years follow-up.