Table 3.
Multivariable Cox regression model analysis of time to tuberculosis diagnosis according to IGRA status
| Tuberculosis cases per person-years of follow-up* | Incidence per 100 000 person-years (95% CI) | HR (95% CI)† | p value | |
|---|---|---|---|---|
| IGRA status | ||||
| Positive | 128/10 684 | 1190 (1000–1420) | 31·9 (20·4–49·8) | <0·0001 |
| Negative | 24/64 537 | 37 (24–55) | 1 (ref) | .. |
| Age, years | ||||
| 16–25 | 62/33 747 | 183 (143–235) | 1·04 (0·74–1·46) | 0·795 |
| 26–35 | 97/42 849 | 226 (185–276) | 1 (ref) | .. |
| Sex | ||||
| Female | 94/33 899 | 277 (226–339) | 1 (ref) | .. |
| Male | 63/41 010 | 153 (120–196) | 0·65 (0·46–0·90) | 0·010 |
| ETS region of origin | ||||
| Africa | 24/7598 | 315 (211–471) | 1 (ref) | .. |
| The Americas or Europe | 0/614 | 0 | 0 | .. |
| East and southeast Asia | 2/1045 | 191 (478–764) | 0·78 (0·17–3·53) | 0·750 |
| South Asia | 58/35 394 | 163 (126–211) | 0·84 (0·42–1·69) | 0·616 |
| Tuberculosis incidence in country of origin (cases per 100 000)‡ | ||||
| 40–149 | 12/3856 | 311 (176–547) | 1 (ref) | .. |
| 150–349 | 67/39 690 | 168 (132–214) | 0·69 (0·33–1·45) | 0·305 |
| >350 | 5/1106 | 451 (188–108) | 0·81 (0·27–2·36) | 0·694 |
| Tuberculosis incidence in area of residence (cases per 100 000)§ | ||||
| ≤9·2 | 8/5668 | 141 (70–282) | 1 (ref) | .. |
| 9·3–31·6 | 61/25 554 | 238 (185–306) | 1·77 (0·83–3·78) | 0·135 |
| >31·6 | 69/37 733 | 182 (144–231) | 1·05 (0·49–2·24) | 0·885 |
| Deprivation index | ||||
| 1–3 deciles (most deprived) | 91/45 531 | 199 (162–245) | 1 (ref) | .. |
| 4–6 deciles | 50/23 543 | 212 (160–280) | 1·06 (0·73–1·54) | 0·750 |
| 7–10 deciles (least deprived) | 11/4965 | 221 (122–400) | 1·25 (0·66–2·36) | 0·486 |
| Year of arrival in England or primary care registration | ||||
| 2011–12 | 12/4684 | 256 (145–451) | 1 (ref) | .. |
| 2013–14 | 16/6923 | 231 (141–377) | 1·51 (0·77–2·97) | 0·224 |
| 2015–16 | 32/17 123 | 186 (132–264) | 0·74 (0·40–1·37) | 0·346 |
| 2017–18 | 24/15 921 | 150 (101–224) | 0·21 (0·10–0·44) | <0·0001 |
IGRA=interferon-γ release assay. HR=hazard ratio. ETS=enhanced tuberculosis surveillance system. LTBI=latent tuberculosis infection.
Included only participants with no missing information for that characteristic.
HR (95% CI) and p value estimates were derived from the total cohort of migrants with a positive IGRA who did not start LTBI treatment, after multiple imputation for missing values by chained equations model (n=34 792); migrants with indeterminate IGRA results or with no results were excluded.
WHO estimated tuberculosis incidence.13
UK Health Security Agency estimated tuberculosis incidence in Clinical Commissioning Group area of residence.