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Table 3 Univariable and multivariable zero-inflated Poisson regression of factors associated with the likelihood of transmitting TB, and the number of subsequent clustered cases for pulmonary TB cases in England, Wales and Northern Ireland, 2010–2014

From: The impact of HIV infection on tuberculosis transmission in a country with low tuberculosis incidence: a national retrospective study using molecular epidemiology

 

Total pulmonary cases

Clustered pulmonary cases (%)

First pulmonary cases (% of clustered cases)

Univariable (number of subsequent cases)

Univariable (non-clustered case)

Multivariable≠ (number of subsequent cases)

Multivariable≠ (non-clustered case)

IRR (95% CI)

OR (95% CI)

IRR (95% CI)

OR (95% CI)

HIV status

 Negative

11,366

6910 (60.8)

1950 (28.2)

1.00

1.00

1.00

1.00

 Positive

545

311 (57.1)

106 (34.1)

0.76 (0.68–0.87)

0.94 (0.72–1.23)

0.75 (0.65–0.86)

1.10 (0.79–1.53)

Year of TB diagnosis

 2010

2028

1205 (59.4)

716 (59.4)

1.00

1.00

1.00

1.00

 2011

2696

1638 (60.8)

546 (33.3)

0.63 (0.59–0.66)

1.69 (1.46–1.96)

0.64 (0.60–0.68)

1.52 (1.29–1.80)

 2012

2650

1670 (63.0)

379 (22.7)

0.39 (0.35–0.43)

1.87 (1.56–2.24)

0.38 (0.34–0.43)

1.53 (1.25–1.88)

 2013

2354

1456 (61.9)

230 (15.8)

0.42 (0.35–0.49)

2.79 (2.20–3.53)

0.40 (0.34–0.48)

2.38 (1.83–3.11)

 2014

2183

1252 (57.4)

185 (14.8)

0.64 (0.52–0.79)

4.53 (3.34–6.14)

0.59 (0.47–0.74)

4.04 (2.87–5.69)

Sex

 Female

4562

2661 (58.3)

765 (28.7)

1.00

1.00

1.00

1.00

 Male

7333

4552 (62.1)

1285 (28.2)

1.04 (0.99–1.09)

0.86 (0.76–0.96)

1.01 (0.95–1.06)

0.81 (0.70–0.93)

 Missing

16

8 (50.0)

6 (75.0)

    

Age (years)

 15–24

2254

1504 (66.7)

405 (26.9)

0.93 (0.87–1.00)

0.78 (0.65–0.92)

0.86 (0.79–0.93)

0.78 (0.63–0.96)

 25–34

3250

1947 (59.9)

575 (29.5)

1.00

1.00

1.00

1.00

 35–44

2089

1314 (62.9)

395 (30.1)

1.30 (1.22–1.39)

0.89 (0.75–1.05)

1.33 (1.24–1.43)

0.99 (0.81–1.22)

 45–54

1566

1000 (63.9)

252 (25.2)

0.90 (0.83–0.99)

0.89 (0.73–1.08)

0.96 (0.87–1.07)

1.08 (0.84–1.38)

 55–64

999

633 (63.4)

167 (26.4)

1.19 (1.09–1.30)

1.10 (0.87–1.39)

1.01 (0.91–1.13)

1.36 (1.01–1.82)

 65+

1753

823 (46.9)

262 (31.8)

1.04 (0.96–1.13)

1.61 (1.34–1.94)

1.03 (0.93–1.14)

1.97 (1.53–2.53)

Ethnicity

 White

3481

2205 (63.3)

522 (23.7)

1.00

1.00

1.00

1.00

 Black African

1926

1270 (65.9)

370 (29.1)

0.96 (0.89–1.02)

0.76 (0.64–0.91)

1.23 (1.12–1.36)

0.91 (0.70–1.19)

 Black Other

406

322 (79.3)

68 (21.1)

0.89 (0.77–1.02)

0.51 (0.35–0.74)

0.86 (0.74–1.01)

0.58 (0.37–0.93)

 Indian sub-continent

4174

2354 (56.4)

758 (32.2)

0.94 (0.88–0.99)

1.15 (1.00–1.33)

0.93 (0.85–1.01)

1.19 (0.94–1.51)

 Mixed/other

1621

894 (55.2)

273 (30.5)

0.60 (0.55–0.66)

1.03 (0.85–1.26)

0.68 (0.60–0.77)

1.10 (0.83–1.46)

 Missing

303

176 (58.1)

65 (36.9)

    

Time since entry to the UK

 UK born

3631

2526 (69.6)

540 (21.4)

1.00

1.00

1.00

1.00

 Within 2 years

1536

833 (54.2)

311 (37.3)

0.70 (0.64–0.75)

1.10 (0.91–1.32)

0.65 (0.59–0.71)

1.27 (0.99–1.63)

 2–5 years

1549

815 (52.6)

267 (32.8)

0.75 (0.69–0.81)

1.24 (1.02–1.50)

0.76 (0.69–0.84)

1.35 (1.05–1.74)

 5–10 years

1543

897 (58.1)

283 (31.5)

0.82 (0.76–0.89)

1.10 (0.91–1.33)

0.76 (0.69–0.83)

1.25 (0.97–1.60)

 More than 10 years

2423

1460 (60.3)

423 (29.0)

0.89 (0.83–0.95)

1.23 (1.04–1.46)

0.84 (0.77–0.91)

1.10 (0.87–1.40)

 Missing

1229

690 (56.1)

232 (33.6)

    

TB lineage

 Beijing

706

525 (74.4)

93 (17.7)

1.00

1.00

1.00

1.00

 Euro-American

5306

3233 (60.9)

898 (27.8)

0.51 (0.47–0.56)

1.05 (0.80–1.39)

0.46 (0.41–0.50)

1.11 (0.80–1.54)

 Central Asian Strain

2955

1948 (65.9)

547 (28.1)

0.72 (0.66–0.79)

1.05 (0.79–1.40)

0.78 (0.70–0.86)

1.01 (0.72–1.43)

 East Asian Indian

1271

551 (43.4)

235 (42.6)

0.42 (0.37–0.48)

1.59 (1.16–2.17)

0.52 (0.45–0.59)

1.54 (1.06–2.23)

 Other/unknown

1673

964 (57.6)

283 (29.4)

0.48 (0.43–0.53)

1.17 (0.86–1.59)

0.43 (0.38–0.48)

1.18 (0.82–1.69)

 Missing

2

      

IMD decile

 1

2581

1654 (64.1)

440 (26.6)

–

–

–

–

 2

2238

1383 (61.8)

396 (28.6)

–

–

–

–

 3

1851

1117 (60.3)

335 (30.0)

–

–

–

–

 4

1425

873 (61.3)

247 (28.3)

–

–

–

–

 5

1039

609 (58.6)

191 (31.4)

–

–

–

–

 6

737

437 (59.3)

125 (28.6)

–

–

–

–

 7

525

306 (58.3)

80 (26.1)

–

–

–

–

 8

486

276 (56.8)

82 (29.7)

–

–

–

–

 9

390

224 (57.4)

63 (28.1)

–

–

–

–

 10

305

171 (56.1)

54 (31.6)

–

–

–

–

 Missing

334

171 (51.2)

43 (25.1)

–

–

–

–

 For each decile increase

–

–

–

0.96 (0.95–0.97)

1.02 (0.99–1.04)

0.96 (0.95–0.97)

1.00 (0.97–1.03)

Drug misuse

 No

10,165

6061 (59.6)

1768 (29.2)

1.00

1.00

1.00

1.00

 Yes

639

507 (79.3)

82 (16.2)

1.14 (1.02–1.27)

0.61 (0.45–0.83)

0.88 (0.76–1.01)

0.84 (0.56–1.28)

 Missing

1107

653 (59.0)

206 (31.5)

    

Alcohol misuse

 No

10,039

6043 (60.2)

1747 (28.9)

1.00

1.00

1.00

1.00

 Yes

670

470 (70.1)

87 (18.5)

1.85 (1.71–2.01)

0.97 (0.74–1.26)

1.69 (1.54–1.86)

1.18 (0.84–1.66)

 Missing

1202

708 (58.9)

222 (31.4)

    

Homelessness

 No

10,398

6277 (60.4)

1799 (28.7)

1.00

1.00

1.00

1.00

 Yes

567

393 (69.3)

85 (21.6)

0.90 (0.80–1.02)

0.74 (0.55–0.99)

0.63 (0.54–0.72)

0.88 (0.59–1.30)

 Missing

946

551 (58.2)

172 (31.2)

    

Imprisonment

 No

9990

5978 (59.8)

1725 (28.9)

1.00

1.00

1.00

1.00

 Yes

553

423 (76.5)

82 (19.4)

1.07 (0.96–1.20)

0.86 (0.76–0.96)

1.10 (0.97–1.26)

0.85 (0.57–1.26)

 Missing

1368

820 (59.9)

249 (30.4)

    

Smear status

 Smear positive

4959

3137 (63.3)

901 (28.7)

1.00

1.29

1.00

1.00

 Smear negative or unknown

6952

4084 (58.7)

1155 (28.3)

0.87 (0.83–0.92)

1.94 (1.78–2.12)

0.83 (0.79–0.88)

1.17 (1.02–1.34)

  1. IRR: incidence rate ratio (Poisson part) for an increased number of subsequent clustered cases. OR: odds ratio (zero-inflated part) for the odds of being a non-clustered case, compared to being the first case of a cluster. Both analyses were restricted to clusters where the first case was pulmonary. IMD: index of multiple deprivation score. IMD score deciles represent relative levels of deprivation of income, employment, health, education, housing and services, crime and living environment for small areas in England and Wales, where 1 = most deprived and 10 = least deprived [29, 30]
  2. ≠Adjusted for all variables shown in the table. The multivariable model included 5694 TB cases after 1052 were excluded due to missing data on one or more of sex (n = 14), ethnicity (n = 192), time since entry to the UK (n = 771) or IMD score (n = 206)
  3. †Cases missing data were considered not to have these social risk factors
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BMC Medicine

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