TABLE 3.
Risk factors for the development of active tuberculosis (TB) among persons infected with Mycobacterium tuberculosis
| Risk factor | Estimated risk of TB relative to persons with no known risk factor |
|---|---|
| High risk | |
| AIDS | 110–170 |
| HIV infection | 50–110 |
| Transplantation (related to immunosuppressive therapy) | 20–74 |
| Silicosis | 30 |
| Chronic renal failure requiring hemodialysis | 10–15 |
| Carcinoma of head and neck | 16 |
| Recent TB infection (two years or less) | 15 |
| Abnormal chest x-ray – fibronodular disease | 16–19 |
| Increased risk | |
| Treatment with glucocorticoids | 4.9 |
| Tumour necrosis factor-alpha inhibitors | 1.5–4 |
| Diabetes mellitus (all types) | 2.0–3.6 |
| Underweight (90% or lower of ideal body weight; for most persons, this corresponds to a body mass index of 20 kg/m2 or lower) | 2–3 |
| Young age when infected (zero to four years of age) | 2.2–5.0 |
| Cigarette smoker (one pack/day) | 2–3 |
| Abnormal chest x-ray – granuloma | 2 |
| Low risk | |
| Infected person, no known risk factor, normal chest x-ray (low risk reactor) | 1 |
Adapted from reference 9. Reproduced with the permission from the Minister of Public Works and Government Services Canada, 2010