Without treatment, TB is a severe and potentially fatal disease. After 5 years without treatment, the outcome of smear-positive pulmonary TB (PTB) in non-HIV-infected patients is as follows1:
- 50 to 60% die (case fatality ratio (CFR) for untreated TB);
- 20 to 25% are cured (spontaneous cure);
- 20 to 25% continue to have symptoms.
In non-HIV infected patients, the CFR is estimated at 3%2. Untreated TB in HIV-infected patients (not on effective antiretroviral therapy) is almost always fatal. Even on antiretroviral therapy, the CFR is higher than in non-HIV infected patients3,4.
Risk factors for poor outcomes of TB treatment (death and relapse) include co-morbidities (e.g. HIV infection, diabetes, COPD), cavities on chest x-ray, high bacillary load and resistance to TB drugs.