## TB Risk Factors in the Indian Population ### Recognized Risk Factors (Options 0, 1, 3) **Key Point:** Multiple modifiable and non-modifiable risk factors significantly influence TB epidemiology in India. | Risk Factor | Relative Risk | Mechanism | Prevalence in Indian TB | |---|---|---|---| | Malnutrition (BMI < 18.5) | 2–3 fold | Impaired cell-mediated immunity | ~30–40% | | Diabetes mellitus | 3–4 fold | Hyperglycemia impairs immune response | 15–20% | | HIV co-infection | 20–30 fold | CD4+ depletion, loss of immunity | ~5–10% in high-burden areas | | Smoking | ↑ severity, NOT protection | Airway damage, impaired clearance | ~40–50% in male TB patients | **High-Yield:** The TB-diabetes co-epidemic in India is particularly significant: - ~1 in 6 TB patients in India has diabetes - Diabetes increases TB risk 3–4 fold - Bidirectional relationship: TB also worsens glycemic control ### Incorrect Statement (Option 2) **Warning:** Smoking does **NOT** reduce TB risk; it **INCREASES** both susceptibility and severity. **Clinical Pearl:** Smoking's role in TB: 1. **Increases infection risk** — impairs mucociliary clearance and alveolar macrophage function 2. **Increases progression risk** — from latent to active TB 3. **Increases disease severity** — cavitary disease, higher bacterial load 4. **Worsens outcomes** — higher treatment failure and relapse rates **Mnemonic: SMOKE Harms TB Control** — Smoking increases Macrophage dysfunction, Oxidative stress, Kills immunity, and Exacerbates severity. ### Why This Matters The distractor reverses the direction of smoking's effect. Smoking is a well-established risk factor for TB in India, especially among males. Confusing this is a common exam trap because students may conflate smoking with other conditions.
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