Role of tuberculin skin test in latent tuberculosis infection in HIV patients in a tertiary care hospital of India

Abstract

Abstract Background: Human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome can affect the natural course of tuberculosis (TB) and pose diagnostic difficulties and may negatively affect the treatment due to frequent drug interactions in the advanced state of disease. Targeted tuberculin skin testing (TST) for latent tuberculosis infection (LTBI) identifies persons at high risk for TB who would benefit by treatment of LTBI, if detected. Materials and Methods: A prospective observational study conducted at the Department of Pulmonary Medicine and Department of Internal Medicine, MIMSR Medical College, Latur, India from November 2012 to October 2013 included all HIV-positive patients attending the outdoor department. A total of 100 HIV-positive patients subjected to TST were studied. The clinical presentation, CD4 count and tuberculin test result were studied. Chi-square test was applied to know the test of significance. Results: In this study of 100 patients, 48 were male, 52 were female and the male to female ratio was 0.92:1, with majority of the cases in the age group of 31-40 years. The mean age of the patients was 35.89 years. The most common mode of transmission of HIV infection was heterosexual in 93 patients (93%), blood transfusion in four patients (4%) and injections in three patients (3%). Of the 100 patients studied, 56 patients were TST negative (56%), whereas 44 patients were TST positive (44%). Of the 100 patients studied, 48 patients had a CD4 count of <200 cells/mm3; of these 48 patients, 37 patients were TST negative and 11 patients were TST positive. Conclusion: TST reactivity varied directly and that of anergy inversely with absolute CD4 counts. TST should be correlated with CD4 count as indurations to protein purified derivative depend on CD4 count. TST in asymptomatic HIV cases, irrespective of CD4 count, would definitely guide regarding decision of chemoprophylaxis in LTBI. The role of TST in the decision to start chemoprophylaxis in LTBI should be considered cautiously in India, as the prevalence of both HIV and TB is high.