Descriptive characteristics of 188 individuals at baseline
| All (%) n=188 n (%) | Healthy/uninfected n=86 n (%) | Healthy/Mycobacterium tuberculosis-infected n=27 n (%) | Extrathoracic TB n=11 n (%) | Intrathoracic TB n=64 n (%) | |
|---|---|---|---|---|---|
| Explanatory variable | |||||
| Sex | |||||
| Male | 80 (42.6) | 24 (27.9) | 15 (55.6) | 6 (54.6) | 35 (54.7) |
| Female | 108 (57.5) | 62 (72.1) | 12 (44.4) | 5 (45.5) | 29 (45.3) |
| Age group | |||||
| 18–29 | 71 (37.8) | 33 (38.4) | 13 (48.2) | 6 (54.6) | 19 (29.7) |
| 30–39 | 57 (30.3) | 24 (27.9) | 8 (29.6) | 4 (36.4) | 21 (32.81) |
| 40–49 | 36 (19.2) | 17 (19.8) | 4 (14.8) | 1 (9.1) | 14 (21.9) |
| ≥50 | 21 (11.2) | 10 (11.6) | 2 (7.4) | 0 (0.0) | 9 (14.1) |
| Missing | 3 (1.6) | 2 (2.3) | 0 (0.0) | 0 (0.0) | 1 (1.6) |
| Ethnicity | |||||
| White | 96 (51.1) | 70 (81.4) | 9 (33.3) | 0 (0.0) | 17 (26.6) |
| Non-white | 87 (46.3) | 16 (18.6) | 17 (63.0) | 11 (100.0) | 43 (67.2) |
| Missing | 5 (2.7) | 0 (0.0) | 1 (3.7) | 0 (0.0) | 4 (6.3) |
| Immigrant status* | |||||
| UK born | 33 (17.6) | 2 (2.33) | 11 (40.7) | 2 (18.2) | 18 (28.1) |
| Non-UK born | 65 (34.6) | 6 (6.98) | 15 (55.6) | 6 (18.2) | 38 (59.4) |
| Missing | 90 (47.87) | 78 (90.7) | 1 (3.7) | 3 (27.3) | 8 (12.5) |
| Explanatory variable | |||||
| Current smoking status | |||||
| Non-smoker | 109 (58.0) | 36 (41.9) | 18 (66.7) | 8 (72.7) | 47 (73.4) |
| Smoker | 79 (42.0) | 50 (58.1) | 9 (33.3) | 3 (27.3) | 17 (26.6) |
| Previous BCG vaccination* | |||||
| No | 41 (21.8) | NA | NA | 3 (27.3) | 38 (62.3) |
| Yes | 30 (16.0) | NA | NA | 7 (63.6) | 23 (37.7) |
| Missing | 117 (62.3) | 86 (100.0) | 27 (100.0) | 1 (9.1) | 3 (4.7) |
| Sputum-smear status† | |||||
| Negative | 31 (16.5) | NA | 4 (36.4) | 27 (42.19) | |
| Positive | 8 (4.3) | NA | NA | 0 (100.0) | 8 (12.5) |
| Missing | 63 (33.5) | 86 (100.0) | 27 (100.0) | 7 (63.6) | 29 (45.3) |
| Comorbidity | |||||
| No | 164 (87.2) | 86 (100.0) | 27 (100.0) | 7 (63.6) | 44 (68.8) |
| Yes | 24 (12.8) | 0 (0.0) | 0 (0.0) | 4 (36.4) | 20 (31.3) |
| Season | |||||
| Winter, December–February | 57 (30.3) | 43 (50.0) | 5 (18.5) | 0 (0.0) | 9 (14.1) |
| Spring, March–May | 32 (17.0) | 5 (5.8) | 5 (18.5) | 4 (36.4) | 18 (28.1) |
| Summer, June–August | 48 (25.5) | 25 (29.1) | 4 (14.8) | 2 (18.2) | 17 (26.6) |
| Autumn, September–November | 51 (27.1) | 13 (15.1) | 13 (48.2) | 5 (45.5) | 20 (31.3) |
*Data on immigrant status and previous BCG vaccination were not collected from convenience sample of healthy volunteers.
†Sputum-smear status—this is only routinely obtained for suspected intrathoracic patients.
NA, data was not collected.