Table 2.

Multivariable Cox regression model analysis of factors associated with time to tuberculosis diagnosis

		Tuberculosis cases per person-years of follow-up*	Incidence per 100 000 person-years (95% CI)	HR (95% CI)†	p value
Model 1
Age, years
	16–25	773/946 153	81 (76–87)	0·85 (0·76–0·94)	0·003
	26–35	671/691 635	97 (89–104)	1 (ref)	..
Sex
	Female	826/829 167	99 (93–106)	1 (ref)	..
	Male	618/807 300	76 (70–82)	0·77 (0·69–0·86)	<0·0001
ETS region of origin
	Africa	389/423 387	91 (83–101)	1 (ref)	..
	The Americas or Europe	0/30 893	0	0	..
	East and southeast Asia	49/98 843	49 (37–65)	0·60 (0·45–0·82)	0·001
	South Asia	931/1 051 901	88 (83–94)	1·16 (0·97–1·39)	0·089
Tuberculosis incidence in country of origin (cases per 100 000)‡
	40–149	192/196 674	97 (84–112)	1 (ref)	..
	150–349	1105/1 297 876	85 (80–90)	0·62 (0·50–0·77)	<0·0001
	>350	72/110 474	65 (51–82)	0·63 (0·47–0·84)	0·002
Tuberculosis incidence in area of residence (cases per 100 000)§
	≤9·2	118/146 624	80 (67–96)	1 (ref)	..
	9·3–31·6	855/970 862	88 (82–94)	1·05 (0·86–1·30)	0·583
	>31·6	428/460 358	92 (84–102)	1·16 (0·93–1·45)	0·161
Deprivation index
	1–3 deciles (most deprived)	788/821 584	95 (89–102)	1 (ref)	..
	4–6 deciles	495/583 213	84 (77–92)	0·89 (0·79–1·00)	0·063
	7–10 deciles (least deprived)	128/196 727	65 (54–77)	0·73 (0·60–0·89)	0·002
Year of arrival in England or primary care registration
	2011–12	477/629 979	75 (69–82)	1 (ref)	..
	2013–14	340/368 240	92 (83–102)	1·21 (1·03–1·42)	0·018
	2015–16	374/362 069	103 (93–114)	1·26 (1·07–1·48)	0·004
	2017–18	178/244 736	72 (62–84)	0·78 (0·63–0·96)	0·024
Pre-entry screening for active tuberculosis
	Yes	322/374 036	86 (77–96)	1·27 (1·03–1·56)	0·022
	No	1124/1 264 200	88 (83–94)	1 (ref)	..
Pre-entry screening: year of arrival in England or primary care registration¶
	2011–12	..	..	1 (ref)	..
	2013–14	..	..	0·92 (0·69–1·23)	0·599
	2015–16	..	..	0·89 (0·67–1·18)	0·430
	2017–18	..	..	0·43 (0·29–0·63)	<0·0001
Time-variant LTBI testing and treatment
	Yes	166/80 995	204 (176–238)	0·76 (0·63–0·91)	0·003
	No	1280/1 557 241	82 (77–86)	1 (ref)	..
LTBI testing and treatment by follow-up period
Model 2 (<6 months follow-up)‖
	Yes	124/26·6	4·65 (3·90–5·54)	9·93 (7·63–12·9)	<0·001
	No	110/42·3	2·59 (2·15–3·13)	1 (ref)	..
Model 3 (>6 months follow-up)**
	Yes	42/80 969	51·8 (38·3–70·1)	0·57 (0·41–0·79)	0·001
	No	1170/1 557 198	75·1 (70·9–79·5)	1 (ref)	..
Model 4 (1-year follow-up)§
	Yes	18/76 490	23·5 (14·8–37·3)	0·36 (0·22–0·58)	<0·001
	No	977/1 555 582	62·8 (58·9–66·8)	1 (ref)	..
Model 5 (2-year follow up)§
	Yes	8/57 548	13·9 (6·95–27·8)	0·36 (0·18–0·73)	0·005
	No	698/1 474 486	47·3 (43·9–50·9)	1 (ref)	..
Model 6 (3-year follow-up)§
	Yes	2/30 296	6·6 (1·65–26·4)	0·29 (0·07–1·18)	0·085
	No	464/1 352 527	34·3 (31·3–37·5)	1 (ref)	..

HR=hazard ratio. ETS=enhanced tuberculosis surveillance system. LTBI=latent TB infection.

^*Included only participants with no missing data for that characteristic.

^†HR (95% CI) and p value estimates were derived from the total cohort of migrants, excluding those who developed tuberculosis 21 days after starting treatment (n=368 077), after multiple imputation for missing values by chained equations model.

^‡WHO estimated tuberculosis incidence.¹³

^§The UK Health Security Agency estimated tuberculosis incidence in Clinical Commissioning Group area of residence.

^¶Effect modification is shown in the multiplicative scale using pre-entry active tuberculosis screening (yes) as the baseline group.

^‖Models 2–6 include the same covariates as model 1 with the addition of the time-variant effect of LTBI testing and treatment.

^**Rate per one person-year (95% CI).