Demographic and clinical characteristics | Smear negative | Smear positive | |||||
Atypical (base) | Typical | Atypical | Typical | ||||
n (%) | n (%) | RRR (95% CI) | n (%) | RRR (95% CI) | n (%) | RRR (95% CI) | |
Assessed, n | 51 | 111 | 33 | 118 | |||
Age (years) | |||||||
>64 | 15 (23.1) | 19 (29.2) | 1.00 | 14 (21.5) | 1.00 | 17 (26.2) | 1.00 |
15–64 | 36 (14.5) | 92 (37.1) | 1.68 (0.71 to 3.92) | 19 (7.6) | 0.56 (0.20 to 1.55) | 101 (40.7) | 2.41 (1.01 to 5.74) |
Sex | |||||||
Female | 22 (15.7) | 53 (37.9) | 1.00 | 13 (9.3) | 1.00 | 52 (37.1) | 1.00 |
Male | 29 (16.8) | 58 (33.5) | 0.77 (0.38 to 1.56) | 20 (11.6) | 1.15 (0.45 to 2.93) | 66 (38.2) | 0.90 (0.44 to 1.83) |
Population group | |||||||
Canadian born | 12 (13.8) | 21 (24.1) | 1.00 | 8 (9.2) | 1.00 | 46 (52.9) | 1.00 |
Foreign born | 39 (17.3) | 90 (40.0) | 1.00 (0.42 to 2.37) | 25 (11.0) | 1.09 (0.36 to 3.32) | 72 (31.7) | 0.40 (0.17 to 0.92) |
Absence of dyspnoea | |||||||
No | 15 (23.4) | 7 (11.0) | 1.00 | 16 (25.0) | 1.00 | 26 (40.6) | 1.00 |
Yes | 36 (14.4) | 104 (41.8) | 4.71 (1.69 to 13.18) | 17 (6.8) | 0.59 (0.22 to 1.60) | 92 (37.0) | 1.85 (0.79 to 4.34) |
Duration of symptoms* | |||||||
<2 weeks | 18 (19.5) | 56 (60.9) | 1.00 | 3 (3.3) | 1.00 | 15 (16.3) | 1.00 |
≥2 weeks | 33 (14.9) | 55 (24.9) | 0.68 (0.31 to 1.75) | 30 (13.6) | 3.86 (0.93 to 15.92) | 103 (46.6) | 2.93 (1.20 to 7.11) |
Antibiotics† | |||||||
No | 35 (18.5) | 89 (47.1) | 1.00 | 13 (6.9) | 1.00 | 52 (27.5) | 1.00 |
Yes‡ | 16 (12.9) | 22 (17.7) | 0.74 (0.31 to 1.75) | 20 (16.1) | 2.14 (0.79 to 5.82) | 66 (53.2) | 1.76 (0.79 to 3.89) |
Epidemiological risk§ | |||||||
None/low | 24 (16.3) | 45 (30.6) | 1.00 | 17 (11.6) | 1.00 | 61 (41.5) | 1.00 |
Moderate to high | 27 (16.3) | 66 (39.8) | 0.89 (0.42 to 1.87) | 16 (9.6) | 1.20 (0.46 to 3.11) | 57 (34.3) | 0.77 (0.36 to 1.61) |
Reactivation risk¶ | |||||||
None/low | 44 (15.2) | 104 (35.9) | 1.00 | 28 (9.7) | 1.00 | 114 (39.3) | 1.00 |
Moderate to high | 7 (30.4) | 7 (30.4) | 0.43 (0.13 to 1.43) | 5 (21.7) | 1.24 (0.32 to 4.80) | 4 (17.4) | 0.18 (0.04 to 0.79) |
CBC** | |||||||
Low risk | 5 (11.4) | 7 (15.9) | 1.00 | 5 (11.4) | 1.00 | 27 (61.4) | 1.00 |
High risk | 46 (17.1) | 104 (38.7) | 1.26 (0.36 to 3.28) | 28 (10.4) | 0.64 (0.15 to 2.61) | 91 (33.8) | 0.49 (0.16 to 1.48) |
*The presence of ‘symptoms’ and the ‘duration of symptoms’ were considered collinear—here we report just on the duration of symptoms.
†One or more broad-spectrum antibiotics prescribed in the 6 months prior to diagnosis.
‡One or more broad-spectrum antibiotic prescription(s) within six months of the PTB diagnosis with no, or a limited and unsustained therapeutic benefit.
§Epidemiological risks none/low=no known occupational risk, travel history, migration from endemic nation, place of residence in a high-incidence indigenous community, recent contact with a known TB case plus no history of TB; OR, a history of TB/latent TB infection (LTBI) that has been adequately treated. Moderate to high=occupational risk, travel history, migration from endemic nation, place of residence in a high-incidence indigenous community, recent contact with a known tuberculosis (TB) case and/or a positive tuberculin skin test (TST)/interferon gamma release assay (IGRA) or a history of TB that was inadequately treated or with no record of treatment.
¶Per the Canadian Tuberculosis Standards, 7th Edition.
**Low risk=combined normal haemoglobin; leucocytosis and anaemia; leucocytosis. High risk=combined normal haemoglobin; normal/low leucocyte count and anaemia; normal/low leucocyte count.