Table 6. Proportion of infected contacts, by age, sex, population group, community-of-residence and contact type (close vs casual/other) that were secondary cases (“attack rate”).
| Characteristic | All Infected contacts n (%) | Disease Type | Attack Rate† % [95% CI] | P-Value | Adjusted Odds Ratio‡ | |
|---|---|---|---|---|---|---|
| LTBI n (%) | Active Disease* n (%) | |||||
| Total Assessed | 1085 | 959 (88.4) | 126 (11.6) | -- | -- | 991 |
| Age Group (years) | ||||||
| <15 | 301 | 247 (82.1) | 54 (17.9) | 17.9 [13.6, 22.3] | REF | 1.0 |
| 15 to 34 | 355 | 317 (89.3) | 38 (10.7) | 10.7 [7.5, 13.9] | 0.008 | 0.65 [0.41, 1.04]§ |
| 35 to 64 | 384 | 351 (91.4) | 33 (8.6) | 8.6 [5.8, 11.4] | 0.0003 | 0.61 [0.37, 1.00] |
| >64 | 44 | 43 (97.7) | 1 (2.3) | 2.3 [0, 6.7] | 0.008 | 0.16 [0.02, 1.23]§ |
| Unknown | 1 | 1 (100.0) | 0 (0.0) | |||
| Sex | ||||||
| Male | 560 | 491 (87.7) | 69 (12.3) | 12.3 [9.6, 15.0] | REF | 1.0 |
| Female | 508 | 451 (88.8) | 57 (11.2) | 11.2 [8.5, 14.0] | 0.58 | 0.84 [0.56, 1.24] |
| Unknown | 17 | 17 (100.0) | 0 (0.0) | |||
| Population Group | ||||||
| Registered First Nations | 823 | 722 (87.7) | 101 (12.3) | 12.3 [10.0, 14.5] | 0.049 | 3.59 [1.27, 10.14] |
| Métis/Other Indigenous | 60 | 41 (68.3) | 19 (31.7) | 31.7 [19.8, 43.5] | <0.0001 | 6.89 [2.04, 23.25] |
| Canadian Non-Indigenous | 93 | 88 (94.6) | 5 (5.4) | 5.4 [0.8, 10.0] | REF | 1.0 |
| Foreign-born | 35 | 34 (97.1) | 1 (2.9) | 2.8 [0, 8.5] | 0.55 | 0.50 [0.05, 4.49] |
| Unknown | 74 | 74 (100.0) | 0 (0.0) | |||
| Community-of-Residence | ||||||
| Reserve Communities | 593 | 536 (90.4) | 57 (9.6) | 9.6 [7.2, 12.0) | 0.65 | 0.29 [0.14, 0.57] |
| Métis Communities | 96 | 68 (70.8) | 28 (29.2) | 29.2 (20.0, 38.3) | 0.0002 | 0.78 [0.34, 1.80] |
| Major Metropolitan | 158 | 141 (89.2) | 17 (10.8) | 10.8 (5.9, 15.6) | REF | 1.0 |
| Non-Major Metropolitan | 229 | 205 (89.5) | 24 (10.5) | 10.5 (6.5, 14.5) | 0.93 | 0.39 [0.18, 0.81] |
| Unknown | 9 | 9 (100.0) | 0 (0.0) | |||
| Contact Type | ||||||
| Close | 567 | 490 (86.4) | 77 (13.6) | 13.6 (10.8, 16.4) | REF | 1.0 |
| Casual/Other | 518 | 469 (90.5) | 49 (9.5) | 9.5 (6.9, 12.0) | 0.034 | 0.66 [0.44, 1.00] |
| Smear Status of Source | ||||||
| Negative | 204 | 190 (93.1) | 14 (6.9) | 6.9 (3.4, 10.3) | REF | 1.0 |
| Positive | 881 | 769 (87.3) | 112 (12.7) | 12.7 (10.5, 14.9) | 0.019 | 1.79 [0.97, 3.29]§ |
* Active disease cases include those identified by contact tracing investigations. There were 70 type I secondary cases, 50 over the age of 14 years and pulmonary, and 56 type II.
† The attack rate refers to the proportion of new infections (the total of new positive TSTs, TST conversions and secondary cases) that were secondary cases in the 30-month transmission window of their source.
‡ Odds ratios highlighted in bold are significant at p<0.05.
§ Indicates odds ratios significant at p<0.10.
REF: Reference group.