Utility of tuberculin and anergy skin testing in predicting tuberculosis infection in human immunodeficiency virus-infected persons in Thailand

SETTING: Chiang Rai, the northernmost province of Thailand, where extensive human immunodeficiency virus (HIV) transmission has resulted in a rapid increase in tuberculosis. OBJECTIVE: To assess the utility of tuberculin and anergy skin testing to identify latent Mycobacterium tuberculosis infection in HIV-infected persons. DESIGN: A cross-sectional study and analysis were conducted to examine reactivity to tuberculin and two control antigens (mumps and candida) in HIV-negative and HIV-positive blood donors and female sex workers. RESULTS: HIV-positive persons had markedly decreased tuberculin reactivity; 14%, 19%, and 40% had an induration of ≥10 mm, ≥ 5 mm, ≥ 2 mm, respectively, while 51% of 525 HIV-negative persons had an induration of ≥ 10 mm (P < 0.001). Mumps and candida positivity (reactions of ≥ 3 mm) were found in 94% and 78% of HIV-negative persons compared with 72% and 61% of HIV-positive persons, respectively (P < 0.001). Although HIV-positive persons had markedly less tuberculin reactivity even at higher CD4+ cell counts (>400 cells/μL), reactivity to mumps and candida was present in more than half of HIV-positive persons with low CD4+ cell counts (≤200 cells/μL). Reaction to control antigens did not predict tuberculin reactivity. CONCLUSION: In this setting, tuberculin and anergy skin testing have a low predictive value in detecting M. tuberculosis infection in HIV-infected persons, and therefore such testing has a limited role in identifying HIV-infected persons who may benefit from tuberculosis preventive therapy programs.