Tuberculin Skin Test Conversion among Individuals with Human Immunodeficiency Virus Infection on Antiretroviral Therapy in a Referral Teaching Hospital, Tehran, Iran

The risk of tuberculosis (TB) is greater for individuals with human immunodeficiency virus (HIV) who are on combined antiretroviral therapy (c-ART) than for the normal population. Therefore, the detection and treatment of latent tuberculosis infections is recommended for all HIV-positive persons with positive tuberculin skin tests (TSTs).
This retrospective cohort study included all HIV-positive individuals with CD4 lymphocyte counts greater than 200 cells/µL and negative TST results, who were taking antiretroviral drugs and had been referred to Imam Khomeini Teaching Hospital Consultation Centre for Clients with Risky Behaviors in Tehran, Iran, from 2008 to 2013. TST conversion to positivity is defined as an induration increase of at least 5 mm compared with a previously negative TST result within a 1-year period. Conversion rates are expressed in person-years of observation.
A total of 113 patients were included in our study. At 1 year, 9 of the 113 TST-negative patients taking c-ART became TST-positive (8%; 8 males and 1 female). The TST conversion incidence rate was 10.09/100 person-years. TST conversion was only found to be associated with sex (odds ratio: 8.64; 95% confidence interval: 1.04–7.56, p = 0.032).
Our results suggest that TSTs should be administered to all HIV-positive patients before beginning isoniazid preventive therapy in Iran.