Effect of pregnancy on interferon gamma release-assay and tuberculin skin test detection of latent TB infection among HIV-infected women in a high burden setting.

Publication Type:

Journal Article


Journal of acquired immune deficiency syndromes (1999) (2017)


BACKGROUND: Peripartum immunologic changes may affect latent TB infection (LTBI) diagnostic performance among HIV-infected women.

METHODS: HIV-infected women were serially-tested with tuberculin skin test (TST) and interferon gamma release assay (IGRA) (QuantiFERON® TB Gold In-tube [QFT]) in pregnancy and weeks postpartum in Kenya. Prevalence, sensitivity and agreement, and correlates of QFT/TST positivity were assessed. Quantitative QFT mitogen and M. tuberculosis antigen (Mtb-Ag) responses were compared by peripartum stage. Incidence of test conversion at 6 weeks postpartum was evaluated in baseline TST-/QFT- women.

RESULTS: Among 100 HIV-infected women, median age was 26 years, median CD4 was 555 cells/mm3, and 88% were on antiretrovirals. More women were QFT+ than TST+ in pregnancy (35.4% vs. 13.5%, p=0.001), and postpartum (29.6% vs. 14.8%, p<0.001). Among 18 consistently QFT+ women, 8 (44%) converted from TST- to TST+, with improved test agreement postpartum (56.9%, ╬║=0.20 to 82.4%, ╬║=0.60). Three initially QFT-/TST- women had test conversion (TST+ and/or QFT+), suggesting new infection [incidence 13.4/100 person19 years]. Mean QFT mitogen (4.46 vs. 7.64 IU/mL, p<0.001) and Mtb-Ag (1.03 vs. 1.54 IU/mL, p=0.03) responses were lower among all women retested in pregnancy vs. postpartum, and specifically among persistently QFT+ women (Mtb-Ag: 3.46 vs. 4.48 IU/mL, p=0.007). QFT indeterminate rate was higher in pregnancy (16%) compared to postpartum (0%) due to lower mitogen response.

CONCLUSION: QFT identified >2-fold more women with LTBI compared to TST in pregnancy and postpartum. Lower QFT Mtb-Ag and mitogen responses in pregnancy compared to postpartum suggest pregnancy-associated immunologic changes may influence LTBI test performance.