Diagnosis of latent tuberculosis among HIV infected patients in Ilorin, Nigeria using tuberculin skin test and interferon gamma release assay

Abstract

Introduction: Latent Tuberculosis Infection (LTBI) screening is recommended for individuals with a known risk factor for progression to active disease especially in the setting of HIV infection. This will ensure early diagnosis and prompt treatment. The purpose of our study was to compare tuberculin skin test (TST) with Interferon Gamma Release Assay (IGRA) in the diagnosis of LTBI among patients with known HIV infection at University of Ilorin Teaching Hospital (UITH), Ilorin.

Methods: this was a hospital based cross-sectional study at the Highly Active Antiretroviral therapy (HAART) Clinic and medical wards of the University of Ilorin Teaching Hospital, Ilorin, Nigeria. A total of 282 consenting patients with HIV infection were recruited. Sociodemographic and clinical information was obtained using a well-structured questionnaire. The screening for LTBI was done using Tuberculin skin test (TST) and Interferon Gamma release assay (IGRA).

Results: the prevalence of LTBI among HIV infected patients was 40.6% and 53.1% using TST and QFT-IT respectively, while the overall prevalence considering positivity to either of the test was 66%. There was mild agreement (κ: 0.218) between TST and QFT-IT in the diagnosis of LTBI among patients with HIV infection. The association between CD4 count and TST was not statistically significant (p value = 0.388) but there was strong association between CD4 cell count and QFT results (p = 0.001).

Conclusion: the prevalence of LTBI is quite high among patients with HIV infection in our locality. There is a need to encourage screening of at-risk individuals to forestall the morbidity and mortality associated with TB in this population.