Observed tuberculosis (TB) incidence and prospective TB risk in Flag-4 registered immigrants
| Observation time/patient-years (TB events) | Incidence rate/100 000 patient-years (95% CI) | Incidence rate ratio (95% CI) | Sig (p value) | *5-year TB risk, % (95% CI) | Adjusted hazard ratio† (95% CI) | Sig (p value) | |
|---|---|---|---|---|---|---|---|
| All | 161461 (296) | 183.3 (163.0 to 205.4) | – | – | 0.75 (0.69 to 0.83) | – | – |
| Age group at primary care registration | |||||||
| 16–35‡ | 94612 (208) | 219.8 (191.0 to 251.8) | 1 | – | 0.90 (0.80 to 1.0) | 1 | – |
| <16 | 33030 (15) | 45.4 (25.4 to 74.9) | 0.21 (0.12 to 0.35) | <0.001 | 0.21 (0.14 to 0.33) | 0.25 (0.15 to 0.42) | <0.001 |
| 36+ | 33819 (73) | 215.9 (169.2 to 271.4) | 0.98 (0.75 to 1.28) | 0.901 | 0.89 (0.72 to 1.08) | 0.77 (0.59 to 1.01) | 0.061 |
| WHO TB incidence region/100 000 population | |||||||
| 150–499‡ | 79460 (269) | 338.5 (299.3 to 381.5) | 1 | – | 1.40 (1.26 to 1.55) | 1 | – |
| <150 | 72617 (11) | 15.1 (7.6 to 27.1) | 0.04 (0.02 to 0.08) | <0.001 | 0.07 (0.04 to 0.10) | 0.04 (0.02 to 0.08) | <0.001 |
| 500+ | 9384 (16) | 170.5 (97.4 to 276.9) | 0.50 (0.30 to 0.83) | 0.005 | 0.91 (0.59 to 1.37) | 0.58 (0.35 to 0.96) | 0.030 |
Outcomes were measured and compared within subgroups stratified by age at primary care registration and WHO TB incidence region of origin. Incidence rates were computed using the total observation period for each group.
*TB risk is presented as the cumulative proportion (%) developing TB at 5 years after Flag-4 registration, using Kaplan–Meier analysis.
†Hazards ratios were adjusted for age at primary care registration and WHO TB incidence in region of origin. Regression plots of Schoenfeld residuals against time approximated zero indicating that the proportional hazards assumption was not violated for either variable group (see Methods).
‡Reference subgroup for calculations of incidence rate ratio and adjusted HR.