TABLE 4.
Incidence rates (IR) and Poisson analysis of the QuantiFERON test (QFT) cohort, with all tuberculosis (TB) cases and incident cases as outcome
| All cases | Incident cases | |||||||||||
| TB events | Person-years | IR (95% CI) | IRR (95% CI) | p-value | LR test | TB events | Person-years | IR (95% CI) | IRR (95% CI) | p-value | LR test | |
| QFT-negative | 4 | 2259.1 | 0.0018 (0.0005–0.0045) | Ref. | 4 | 2259.1 | 0.0018 (0.0005–0.0045) | Ref. | ||||
| QFT-positive | 15 | 804.8 | 0.0186 (0.0104–0.0307) | 22.6435 (6.8743–74.5860) | <0.001 | 9 | 804.8 | 0.0112 (0.0051–0.0212) | 12.7057 (3.4510–46.7796) | <0.001 | 0.0012 | |
| No LTBI treatment# | 11 | 265.6 | 0.0414 (0.0207–0.0741) | Ref. | 6 | 265.6 | 0.0226 (0.0083–0.0492) | Ref. | ||||
| LTBI treatment# | 4 | 539.3 | 0.0074 (0.0020–0.0190) | 0.1711 (0.0486–0.6020) | 0.0060 | 0.0014 | 3 | 539.3 | 0.0056 (0.0011–0.0163) | 0.2249 (0.0508–0.9967) | 0.049 | 0.039 |
| Female | 8 | 1371.7 | 0.0058 (0.0025–0.0115) | Ref. | 5 | 1371.7 | 0.0036 (0.0012–0.0085) | Ref. | ||||
| Male | 11 | 1690.1 | 0.0065 (0.0032–0.0116) | 0.8780 (0.3546–2.1739) | 0.7790 | 0.0200 | 8 | 1690.1 | 0.0047 (0.0020–0.0093) | 1.1095 (0.3621–3.3999) | 0.856 | 0.8 |
| Age | –1.0239 (0.9390–1.1165) | 0.5930 | 0.1800 | 1.0076 (0.9062–1.1205) | 0.888 | 0.9 | ||||||
| Area of birth | ||||||||||||
| Indian subcontinent | 17 | 2432.3 | 0.0070 (0.0041–0.0112) | Ref. | 12 | 2432.3 | 0.0049 (0.0025–0.0086) | Ref. | ||||
| Sub-Saharan Africa | 2 | 248.8 | 0.0080 (0.0010–0.0290) | 0.7514 (0.1491–3.7856) | 0.7290 | 1 | 248.8 | 0.0040 (0.0001–0.0224) | 0.5293 (0.0657–4.2641) | 0.55 | ||
| Rest of world | 0 | 382.9 | 0.0000 (0.0000–0.0096) | 0.0000 (0.0000–0.0000) | <0.001 | 0.1140 | 0 | 382.9 | 0.0000 (0.0000–0.0096) | 0.0000 (0.0000–0.0000) | <0.001 | 0.2 |
Data are presented as n, unless otherwise stated. IRR: incidence rate ratio; LR: likelihood ratio; LTBI: latent TB infection. #: of persons with positive LTBI test.