Table 1.
Risk of tuberculosis (TB) among exposed populations
| Population and definition of positive test result | Among test positive participants | Compared with test negative participants | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| No of cohorts | No of participants | Total (mean) person years follow-up | Active TB events (%)* | TB rate per 1000 person years (95% CI)† | I2 (%) | No of cohorts | Incidence rate ratio (95% CI)† | I2 (%) | ||
| General population‡ | ||||||||||
| TST ≥10 mm | 3 | 33 811 | 249 093 (7.4) | 55 (0.2) | 0.3 (0.1 to 1.1) | 96 | - | - | - | |
| Close and casual contacts (together)§ | ||||||||||
| All age groups: | ||||||||||
| All IGRA positive | 9 | 2199 | 6667 (3.0) | 89 (4.0) | 13.3 (10.8 to 16.4) | 0 | 7 | 8.4 (5.2 to 13.5) | 19 | |
| TST ≥5 mm | 4 | 7861 | 32 708 (4.2) | 227 (2.8) | 8.4 (4.3 to 16.5) | 95 | 4 | 12.5 (6.9 to 22.5) | 48 | |
| TST ≥10 mm | 5 | 5728 | 22 561 (3.9) | 97 (2.6) | 9.4 (4.0 to 21.8) | 93 | 5 | 6.9 (3.3 to 14.4) | 54 | |
| Age <18 years: | ||||||||||
| TST ≥5 mm | 2 | 1169 | 2766 (2.4) | 55 (6.6) | 14.7 (1.4 to 153.6) | 97 | 2 | 20.1 (2.9 to 140.6) | 77 | |
| TST ≥10 mm | 4 | 1002 | 2357 (2.4) | 69 (7.2) | 23.4 (8.0 to 68.4) | 92 | 3 | 21.2 (6.4 to 70.2) | 75 | |
| Close contacts only¶ | ||||||||||
| All age groups: | ||||||||||
| All IGRA positive | 7 | 1663 | 4617 (2.8) | 114 (6.5) | 22.4 (12.1 to 41.8) | 87 | 6 | 13.1 (3.3 to 51.9) | 86 | |
| TST ≥5 mm | 9 | 7626 | 37 696 (4.9) | 340 (3.8) | 10.5 (7.7 to 14.3) | 83 | 8 | 3.7 (2.1 to 6.5) | 66 | |
| TST ≥10 mm | 13 | 8849 | 29 970 (3.4) | 296 (2.7) | 10.3 (6.1 to 17.4) | 94 | 11 | 2.5 (1.3 to 4.8) | 86 | |
| Age <18 years: | ||||||||||
| QFT-GIT positive | 2 | 159 | 305 (1.9) | 6 (2.3) | 14.5 (1.7 to 120.5) | 27 | 1 | 13 (4.9 to 34.6) | N/A | |
| TST ≥10 mm | 3 | 584 | 1152 (2.0) | 17 (2.4) | 12.6 (2.3 to 69.8) | 88 | 2 | 4.2 (1.8 to 9.7) | 0 | |
| All studies in contacts above pooled** | ||||||||||
| All IGRA positive | 19 | 4060 | 11 743 (2.9) | 211 (4.6) | 17.0 (12.9 to 22.4) | 81 | 15 | 10.8 (6.1 to 19.0) | 74 | |
| TST ≥5 mm | 18 | 19 628 | 90 266 (4.6) | 615 (2.8) | 8.4 (5.6 to 12.6) | 96 | 16 | 6.0 (3.9 to 9.2) | 70 | |
| TST ≥10 mm | 27 | 18 414 | 69 596 (3.8) | 461 (2.6) | 9.4 (6.3 to 14.1) | 94 | 22 | 4.1 (2.6 to 6.4) | 82 | |
TST=tuberculin skin test; IGRA=interferon-gamma release assay; QFT-GIT=QuantiFERON Gold-In-Tube; N/A=not applicable.
Percentage represents pooled cumulative incidence estimated from random effects meta-analysis.
Pooled estimates using random-effects meta-analysis.
Data provided for reference. Populations are from British Columbia and Saskatchewan, Canada, and Florida, USA.
Studies were conducted in populations of contacts, with no stratification by intensity of exposure or closeness of contact.
Studies were conducted in populations of contacts that were either solely close contacts or had outcomes reported stratified by close and casual contact.
Representative of all studies in contacts, regardless of intensity of exposure. All studies included if >100 participants were tested. Participants are not double counted (i.e. we did not pool cohorts coming from the same study for which participants may fall into more than one group, such as the all ages group and the <18 age group, instead we only included the all age group).