• Jyoti S Mathad, Ramesh Bhosale, Vikrant Sangar, Vidya Mave, Nikhil Gupte, Savita Kanade, Ashwini Nangude, Kavita Chopade, Nishi Suryavanshi, Prasad Deshpande, Vandana Kulkarni, Marshall J Glesby, Daniel Fitzgerald, Renu Bharadwaj, Pradeep Sambarey, and Amita Gupta.
• Division of Infectious Diseases, Weill Cornell Medical College, New York, New York, United States of America.
• Plos One. 2014 Jan 1;9(3):e92308.

BackgroundTargeted screening for latent TB infection (LTBI) in vulnerable populations is a recommended TB control strategy. Pregnant women are at high risk for developing TB and likely to access healthcare, making pregnancy an important screening opportunity in developing countries. The sensitivity of the widely-used tuberculin skin test (TST), however, may be reduced during pregnancy.MethodsWe performed a cross-sectional study comparing the TST with the QuantiFERON Gold In-tube (QGIT) in 401 HIV-negative women presenting antepartum (n = 154), at delivery (n = 148), or postpartum (n = 99) to a government hospital in Pune, India. A subset of 60 women enrolled during pregnancy was followed longitudinally and received both tests at all three stages of pregnancy.ResultsThe QGIT returned significantly more positive results than the TST. Of the 401 women in the cross-sectional study, 150 (37%) had a positive QGIT, compared to 59 (14%) for the TST (p<0.005). Forty-nine (12%) did not have their TST read. Of 356 who had both results available, 46 (13%) were concordant positive, 91 (25%) were discordant (12 (3%) TST+/QGIT-; 79 (22%) TST-/QGIT+), and 206 (57%) concordant negative. Comparison by stage of pregnancy revealed that QGIT percent positivity remained stable between antepartum and delivery, unlike TST results (QGIT 31-32% vs TST 11-17%). Median IFN-γ concentration was lower at delivery than in antepartum or postpartum (1.66 vs 2.65 vs 8.99 IU/mL, p = 0.001). During postpartum, both tests had significantly increased positives (QGIT 31% vs 32% vs 52%, p = 0.01; TST 17% vs 11% vs 25%, p<0.005). The same trends were observed in the longitudinal subset.ConclusionsTiming and choice of LTBI test during pregnancy impact results. QGIT was more stable and more closely approximated the LTBI prevalence in India. But pregnancy stage clearly affects both tests, raising important questions about how the complex immune changes brought on by pregnancy may impact LTBI screening.

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