Cluster size and association with demographics, social risk factors and clinical characteristics of the first two cases in a TB cluster; a univariable and multivariable logistic regression model, universal MIRU-VNTR, London 2010–2012 (N=570)
| Univariable analysis | Multivariable analysis | |||||
|---|---|---|---|---|---|---|
| Variable | No (%) of large (≥5 cases) clusters | No (%) of small (2–4 cases) clusters | OR (95% CI) | p Value* | Adjusted OR (95% CI) | p Value* |
| Total | 101 (17.7) | 469 (82.3) | ||||
| Gender | ||||||
| ≥One male | 85 (84.2) | 391 (83.4) | 1.1 (0.6 to 1.9) | 0.85 | 0.8 (0.4 to 1.6) | 0.55 |
| No male | 16 (15.8) | 78 (16.6) | ||||
| Age | ||||||
| At least one case ≤30 years | 77 (76.2) | 329 (70.2) | 1.4 (0.8 to 2.2) | 0.22 | 1.5 (0.9 to 2.6) | 0.14 |
| No cases ≤30 years | 24 (23.8) | 140 (29.9) | ||||
| Country of birth | ||||||
| ≥One case UK born | 29 (28.7) | 137 (29.2) | 1.0 (0.6 to 1.6) | 0.92 | ||
| Non-UK born | 72 (71.3) | 332 (70.8) | ||||
| Social risk factors | ||||||
| ≥One case with any social risk factors | 22 (21.8) | 75 (16.0) | 1.5 (0.9 to 2.5) | 0.16† | ||
| No social risk factors | 79 (78.2) | 394 (84.0) | ||||
| History of or currently in prison | ||||||
| ≥One case with prison history | 10 (9.9) | 12 (2.6) | 5.7 (1.9 to 17.5) | <0.01 | 2.8 (1.1 to 7.3) | 0.04 |
| 91 (90.1) | 457 (97.4) | |||||
| History of or currently homeless | ||||||
| ≥One case with history or currently homeless | 13 (12.9) | 31 (6.6) | 1.8 (0.7 to 4.3) | 0.21 | ||
| 88 (87.1) | 438 (93.4) | |||||
| History of or current drug misuse | ||||||
| ≥One case with drug misuse | 10 (9.9) | 24 (5.1) | 2.0 (0.7 to 5.8) | 0.21 | ||
| 91 (90.1) | 445 (94.9) | |||||
| History of or current alcohol misuse | ||||||
| ≥One case with alcohol misuse | 10 (9.9) | 37 (7.9) | 1.7 (0.7 to 4.1) | 0.26 | ||
| 91 (90.1) | 432 (92.1) | |||||
| Clinical presentation | ||||||
| First two cases extrapulmonary only | 16 (15.8) | 79 (16.8) | 0.9 (0.5 to 1.7) | 0.81 | ||
| 85 (84.2) | 390 (83.2) | |||||
| First two cases pulmonary only | 50 (49.5) | 204 (43.5) | 1.3 (0.8 to 2.0) | 0.27 | ||
| 51 (50.5) | 265 (56.5) | |||||
| ≥One case with smear negative pulmonary TB | 43 (42.6) | 196 (41.8) | 1.0 (0.7 to 1.6) | 0.89 | ||
| 58 (57.4) | 273 (58.2) | |||||
| ≥One case with smear positive pulmonary TB | 52 (51.5) | 226 (48.2) | 1.1 (0.7 to 1.8) | 0.55 | ||
| 49 (48.5) | 243 (51.8) | |||||
| Notification interval | ||||||
| <90 days between first two cases | 52 (51.5) | 120 (25.6) | 3.1 (2.0 to 4.8) | <0.001 | 2.9 (1.8 to 4.6) | <0.01 |
| ≥90 days between first two cases | 49 (48.5) | 349 (74.4) | ||||
| Drug resistance | ||||||
| At least one case with any resistance | 12 (11.9) | 57 (12.2) | 1.0 (0.5 to 1.9) | 0.94 | ||
| No resistance | 89 (88.1) | 412 (87.9) | ||||
| Previous TB diagnosis | ||||||
| ≥One case with previous TB diagnosis | 15 (14.9) | 49 (10.5) | 1.5 (0.8 to 2.8) | 0.21 | ||
| No previous TB diagnosis | 86 (85.2) | 420 (89.6) | ||||
| Geography | ||||||
| Clusters regionally | 94 (93.1) | 261 (55.7) | 10.7 (4.9 to 23.6) | <0.001 | 10.3 (4.6 to 22.9) | <0.01 |
| Clusters locally | 7 (6.9) | 208 (44.4) | ||||
*Significant results are in bold, those p≤0.2 included in multivariable model.
†Not included in final model due to colinearity with prison history variable.
MIRU-VNTR, multiple interspersed repetitive units-variable number tandem repeats.