| Variable | No. (%) of participants with new or prior TB infection* | Crude OR (95% CI)† | Adjusted OR (95% CI)†‡ | |
|---|---|---|---|---|
| Disease (n = 44) | No disease (n = 89) | |||
| Age, yr | ||||
| < 15 | 12 (27) | 19 (21) | Reference | Reference |
| 15-29 | 22 (50) | 39 (44) | 0.9 (0.4-2.3) | 1.0 (0.3-2.8) |
| ≥ 30 | 10 (23) | 31 (35) | 0.5 (0.2-1.3) | 1.0 (0.3-3.0) |
| Sex | ||||
| Male | 22 (50) | 40 (45) | Reference | Reference |
| Female | 22 (50) | 49 (55) | 0.8 (0.4-1.5) | 0.8 (0.4-1.7) |
| Tobacco smoking | ||||
| Not current smoker | 15 (34) | 26 (30) | Reference | Not in model |
| Current smoker | 29 (66) | 62 (70) | 0.8 (0.4-1.8) | |
| Annual personal income, $§ | ||||
| < 20 000 | 31 (77) | 51 (60) | Reference | Reference |
| ≥ 20 000 | 9 (23) | 34 (40) | 0.4 (0.2-1.05) | 0.4 (0.2-1.1) |
| Prior TB infection | ||||
| Not documented TST-positive before November 2011 | 35 (79) | 53 (60) | Reference | Reference |
| Documented TST-positive before November 2011 | 9 (21) | 36 (40) | 0.4 (0.2-0.8) | 0.4 (0.2-0.9) |
| Heating method | ||||
| Forced air | 41 (93) | 83 (93) | Reference | Not in model |
| Radiator | 3 (7) | 6 (7) | 1.0 (0.3-3.4) | |
| No. of people per room¶ | ||||
| Among participants living with a smear-positive person | 1.9 ± 0.4 | 1.6 ± 0.6 | 1.3 (1.1-1.6) | 1.3 (1.2-1.5) |
| Among participants not living with a smear-positive person | 1.2 ± 0.5 | 1.1 ± 0.5 | 1.1 (0.9-1.2) | 1.1 (0.9-1.3) |
| Ventilation with heating on relative to median (1.66 air changes per hour)** | ||||
| < Median | 36 (82) | 67 (75) | Reference | Not in model |
| ≥ Median | 8 (18) | 22 (25) | 0.7 (0.3-1.5) | |
| Volume of living area relative to median (65.5 m3) | ||||
| < Median | 13 (30) | 44 (49) | Reference | Not in model |
| ≥ Median | 27 (61) | 59 (66) | 2.3 (1.1-5.0) | |
| Visited any dwelling used for social activities | 21 (48) | 50 (56) | 0.7 (0.3-1.6) | Not in model |
| Lived with smear-positive person†† | 13 (30) | 16 (18) | 1.9 (0.9-4.1) | 0.8 (0.3-1.8) |
Note: CI = confidence interval, OR = odds ratio, TB = tuberculosis, TST = tuberculin skin testing.
*Except where stated otherwise.
†CIs where OR excludes 1.0 are in bold.
‡Adjusted OR from the model that included all variables, except where indicated, plus an interaction term between occupancy and living with a smear-positive person that was statistically significant (p = 0.04).
§Eight participants with missing data on income status were excluded from the final model.
¶Interaction term between occupancy and living with a smear-positive person was not statistically significant in univariate analysis (p = 0.1), and was significant in the multivariate model (p = 0.04). As an example of interpretation, if we were to compare 2 participants who did not live together and whose dwellings differed in occupancy by 1 person per room, the unadjusted odds of disease would be 30% higher (as the crude OR is 1.3) for the participant living in the home with the greater number of people per room.
**In the living area. Lowest ventilation measured in the living area also was not associated with disease (data not shown).
††Adjusted OR shows association between living with someone with smear-positive TB and disease if living in a dwelling with 1.2 persons per room (chosen because it was the median number of people per room).