Diagnosis of latent tuberculosis infection among HIV discordant partners using interferon gamma release assays
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
BMC Infectious Diseases 2011, 11:264 doi:10.1186/1471-2334-11-264Published: 30 September 2011
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).
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.
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).
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.