Table 4 Univariable and multivariable zero-inflated Poisson regression of factors associated with the likelihood of being the first case of a cluster, and the number of subsequent clustered cases for extra-pulmonary TB cases in England, Wales and Northern Ireland, 2010–2014
|  | Total extra-pulmonary cases | Clustered cases (%) | First extra-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 | 6739 | 3389 (50.3) | 722 (21.3) | 1.00 | 1.00 | 1.00 | 1.00 |
 Positive | 214 | 99 (46.3) | 22 (22.2) | 4.16 (3.71–4.67) | 1.38 (0.86–2.19) | 3.62 (3.12–4.19) | 1.93 (1.12–3.33) |
Year of TB diagnosis | |||||||
 2010 | 1146 | 590 (51.5) | 293 (49.7) | 1.00 | 1.00 | 1.00 | 1.00 |
 2011 | 1600 | 805 (50.3) | 242 (30.1) | 0.77 (0.71–0.84) | 1.65 (1.34–2.02) | 0.72 (0.66–0.80) | 1.45 (1.15–1.84) |
 2012 | 1677 | 855 (51.0) | 122 (14.3) | 0.56 (0.48–0.66) | 2.84 (2.21–3.64) | 0.60 (0.51–0.71) | 2.57 (1.93–3.41) |
 2013 | 1342 | 674 (50.2) | 62 (9.2) | 0.39 (0.29–0.51) | 2.83 (1.94–4.13) | 0.45 (0.34–0.61) | 2.82 (1.88–4.22) |
 2014 | 1188 | 564 (47.5) | 25 (4.4) | 0.90 (0.74–1.10) | 6.86 (4.36–10.80) | 1.11 (0.82–1.51) | 7.82 (4.67–13.11) |
Sex | |||||||
 Female | 2959 | 1492 (50.4) | 323 (21.6) | 1.00 | 1.00 | 1.00 | 1.00 |
 Male | 3990 | 1995 (50.0) | 421 (21.1) | 1.25 (1.15–1.35) | 1.11 (0.94–1.31) | 1.22 (1.12–1.34) | 0.99 (0.81–1.21) |
 Missing | 4 | 1 (25.0) | (0.0) |  |  |  |  |
Age (years) | |||||||
 15–24 | 984 | 555 (56.4) | 111 (20.0) | 2.26 (2.01–2.54) | 1.10 (0.85–1.42) | 1.66 (1.46–1.89) | 1.07 (0.80–1.45) |
 25–34 | 2382 | 1192 (50.0) | 266 (22.3) | 1.00 | 1.00 | 1.00 | 1.00 |
 35–44 | 1489 | 727 (48.8) | 156 (21.5) | 1.67 (1.49–1.87) | 1.27 (1.01–1.60) | 1.43 (1.26–1.61) | 1.32 (1.00–1.75) |
 45–54 | 822 | 423 (51.5) | 83 (19.6) | 1.37 (1.19–1.59) | 1.19 (0.89–1.58) | 1.39 (1.18–1.63) | 1.46 (1.02–2.10) |
 55–64 | 489 | 257 (52.6) | 52 (20.2) | 1.73 (1.48–2.02) | 1.18 (0.84–1.66) | 1.92 (1.60–2.31) | 1.45 (0.94–2.24) |
 65+ | 787 | 334 (42.4) | 76 (22.8) | 1.08 (0.92–1.26) | 1.34 (1.00–1.81) | 0.94 (0.78–1.14) | 1.40 (0.92–2.12) |
Ethnicity | |||||||
 White | 510 | 237 (46.5) | 49 (20.7) | 1.00 | 1.00 | 1.00 | 1.00 |
 Black African | 1285 | 761 (59.2) | 150 (19.7) | 1.76 (1.45–2.14) | 0.74 (0.51–1.08) | 0.85 (0.65–1.10) | 0.49 (0.27–0.89) |
 Black Other | 182 | 136 (74.7) | 17 (12.5) | 3.69 (2.92–4.66) | 0.62 (0.32–1.19) | 2.84 (2.18–3.70) | 0.57 (0.26–1.25) |
 Indian sub-continent | 3905 | 1844 (47.2) | 414 (22.5) | 1.21 (1.00–1.46) | 0.96 (0.68–1.35) | 0.64 (0.49–0.83) | 0.64 (0.36–1.12) |
 Mixed/other | 904 | 436 (48.2) | 101 (23.2) | 0.97 (0.78–1.21) | 0.80 (0.54–1.20) | 0.58 (0.44–0.78) | 0.50 (0.27–0.93) |
 Missing | 167 | 74 (44.3) | 13 (17.6) |  |  |  |  |
Time since entry to the UK | |||||||
 UK born | 800 | 474 (59.3) | 86 (18.1) | 1.00 | 1.00 | 1.00 | 1.00 |
 Within 2 years | 999 | 480 (48.0) | 107 (22.3) | 1.75 (1.52–2.01) | 1.51 (1.09–2.10) | 2.06 (1.70–2.50) | 2.56 (1.62–4.05) |
 2–5 years | 1450 | 694 (47.9) | 156 (22.5) | 0.72 (0.61–0.84) | 1.16 (0.85–1.59) | 0.99 (0.81–1.22) | 1.72 (1.10–2.70) |
 5–10 years | 1200 | 588 (49.0) | 134 (22.8) | 0.87 (0.74–1.01) | 1.20 (0.87–1.65) | 1.16 (0.94–1.42) | 1.83 (1.15–2.89) |
 More than 10 years | 1692 | 869 (51.4) | 185 (21.3) | 0.95 (0.83–1.09) | 1.15 (0.85–1.56) | 1.28 (1.04–1.57) | 1.42 (0.91–2.23) |
 Missing | 812 | 383 (47.2) | 76 (19.8) |  |  |  |  |
TB lineage | |||||||
 Beijing | 335 | 245 (73.1) | 34 (13.9) | 1.00 | 1.00 | 1.00 | 1.00 |
 Euro-American | 2007 | 1067 (53.2) | 236 (22.1) | 0.46 (0.39–0.54) | 1.21 (0.79–1.87) | 0.41 (0.34–0.49) | 1.16 (0.70–1.93) |
 Central Asian Strain | 2325 | 1337 (57.5) | 255 (19.1) | 0.75 (0.65–0.87) | 1.36 (0.89–2.09) | 0.76 (0.64–0.90) | 1.37 (0.82–2.26) |
 East Asian Indian | 1403 | 495 (35.3) | 133 (26.9) | 0.48 (0.41–0.58) | 2.18 (1.40–3.42) | 0.55 (0.45–0.67) | 2.07 (1.23–3.48) |
 Other | 881 | 342 (38.8) | 85 (24.9) | 0.66 (0.56–0.79) | 2.17 (1.36–3.47) | 0.62 (0.51–0.75) | 1.92 (1.12–3.30) |
 Missing | 2 |  |  |  |  |  |  |
IMD decile | |||||||
 1 | 1352 | 706 (52.2) | 160 (22.7) | – | – | – | – |
 2 | 1407 | 747 (53.1) | 156 (20.9) | – | – | – | – |
 3 | 1157 | 587 (50.7) | 136 (23.2) | – | – | – | – |
 4 | 876 | 441 (50.3) | 72 (16.3) | – | – | – | – |
 5 | 616 | 297 (48.2) | 75 (25.3) | – | – | – | – |
 6 | 446 | 215 (48.2) | 45 (20.9) | – | – | – | – |
 7 | 313 | 147 (47.0) | 26 (17.7) | – | – | – | – |
 8 | 242 | 122 (50.4) | 30 (24.6) | – | – | – | – |
 9 | 220 | 83 (37.7) | 17 (20.5) | – | – | – | – |
 10 | 169 | 72 (42.6) | 12 (16.7) | – | – | – | – |
 Missing | 155 | 71 (45.8) | 15 (21.1) | – | – | – | – |
 For each decile increase | – | – | – | 0.93 (0.92–0.95) | 1.03 (1.00–1.07) | 0.97 (0.95–0.99) | 1.03 (0.99–1.08) |
Drug misuse | |||||||
 No | 6371 | 3180 (49.9) | 675 (21.2) | 1.00 | 1.00 | 1.00 | 1.00 |
 Yes | 63 | 44 (69.8) | 7 (15.9) | 0.41 (0.21–0.82) | 0.34 (0.10–1.18) | 0.49 (0.27–0.90) | 0.31 (0.06–1.66) |
 Missing | 519 | 264 (50.9) | 62 (23.5) |  |  |  |  |
Alcohol misuse | |||||||
 No | 6221 | 3117 (50.1) | 654 (21.0) | 1.00 | 1.00 | 1.00 | 1.00 |
 Yes | 106 | 58 (54.7) | 13 (22.4) | 1.44 (1.13–1.83) | 0.89 (0.47–1.66) | 1.79 (1.34–2.38) | 1.09 (0.47–2.51) |
 Missing | 626 | 313 (50.0) | 77 (24.6) |  |  |  |  |
Homelessness | |||||||
 No | 6373 | 3203 (50.3) | 679 (21.2) | 1.00 | 1.00 | 1.00 | 1.00 |
 Yes | 99 | 56 (56.6) | 7 (12.5) | 0.29 (0.12–0.72) | 0.71 (0.21–2.33) | 0.23 (0.09–0.58) | 0.62 (0.10–3.94) |
 Missing | 481 | 229 (47.6) | 58 (25.3) |  |  |  |  |
Imprisonment | |||||||
 No | 6220 | 3119 (50.1) | 657 (21.1) | 1.00 | 1.00 | 1.00 | 1.00 |
 Yes | 96 | 61 (63.5) | 8 (13.1) | 0.06 (0.03–0.13) | 1.11 (0.94–1.31) | 0.17 (0.04–0.82) | 0.36 (0.01–8.94) |
 Missing | 637 | 308 (48.4) | 79 (25.6) |  |  |  |  |