Open Access Highly Accessed Research article

Diagnosis of latent tuberculosis infection among HIV discordant partners using interferon gamma release assays

Naasha J Talati1*, Esteban Gonzalez-Diaz2, Charles Mutemba3, Joyanna Wendt4, William Kilembe3, Lawrence Mwananyanda3, Elwyn Chomba3, Susan Allen35, Carlos del Rio45 and Henry M Blumberg45

Author Affiliations

1 Department of Medicine, University of Pennsylvania, Philadelphia, PA 19019, USA

2 Department of Medicine, Hospital Civil de Guadalajara, Guadalajara 44280, Mexico

3 Zambia Emory HIV Research Project, Lusaka, Zambia

4 Department of Medicine, Emory University, Atlanta 30329, USA

5 Rollins School of Public Health, Emory University, Atlanta 30329, USA

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BMC Infectious Diseases 2011, 11:264  doi:10.1186/1471-2334-11-264

Published: 30 September 2011

Abstract

Background

There is limited data on the effect of HIV status and CD4 counts on performance of Interferon-g Release assays (IGRAs) for diagnosis of latent tuberculosis infection (LTBI).

Methods

A cross sectional study was conducted to assess the prevalence of and risk factors for a positive diagnostic test for LTBI, using tuberculin skin test (TST) and IGRAs among HIV-discordant couples in Zambia.

Results

A total of 596 subjects (298 couples) were enrolled. Median CD4 count among HIV positive persons was 388 cells/μl, (range 51-1330). HIV negative persons were more likely than their HIV positive partner, to have a positive diagnostic test for LTBI with TST (203 vs 128), QFT (171 vs 109) and TSPOT (156 vs. 109). On multivariate analysis, HIV negative status was an independent predictor for a positive QFT (OR = 2.22, 95% CI 1.42- 3.46) and TSPOT (OR = 1.79, 95% CI 1.16-2.77). Among HIV positive subjects a CD4 count ≥ 388 cells/μl was associated with a positive TST (OR = 1.76 95% CI 1.10-2.82) and QFT (OR = 1.71 95% CI 1.06-2.77) but not TSPOT (OR = 1.20 95% CI 0.74-1.94).

Conclusions

Persons with HIV had significantly fewer positive diagnostic tests for LTBI with TST, QFT and TSPOT. Persons with a CD4 count < 388 cells/μl were less likely to have a positive TST or QFT, but not less likely to have a positive TSPOT. TSPOT may perform better than TST or QFT in HIV positive individuals.