Screening for tuberculosis prior to isoniazid preventive therapy among HIV-infected gold miners in South Africa.

SETTING Human immunodeficiency virus (HIV) clinic for employees of a gold mine, Free State, South Africa. OBJECTIVE To evaluate the process of screening for active tuberculosis (TB) prior to commencing TB preventive therapy in HIV-infected individuals. DESIGN Cross-sectional study comparing performance of various combinations of screening tests for TB against a gold standard diagnosis of TB based on symptoms, chest radiograph (CXR), sputum microscopy and culture. RESULTS Of 899 individuals, 44 (4.9%) had TB. The most sensitive symptom combination (59.1%) was any of night sweats, new or worsening cough or reported weight loss; measured weight loss > 5% or abnormal CXR increased sensitivity to 90.9%. Sputum microscopy did not increase sensitivity further, but including World Health Organization HIV clinical staging or CD4 count did. As the specificity of all these combinations was low, many individuals required further investigation to rule out TB. TB prevalence was high (11.7%) among individuals with a CD4 count < 200/mm3. CONCLUSION CXR greatly increased the sensitivity of screening for TB in this population. Sputum microscopy conferred no additional benefit among asymptomatic patients with a normal CXR. The high prevalence of TB amongst those with a low CD4 count underlines the importance of screening for active TB prior to commencing TB preventive therapy, and before antiretroviral therapy.