Tuberculin test versus interferon gamma release assay in pregnant women with household contacts of tuberculosis patients

Abstract

Background: Pregnant women who live in tuberculosis (TB)-affected households are more likely to develop latent TB infection (LTBI), which often escapes treatment. This study aims to determine if Interferon-gamma release (IGRA) is reliable in screening for LTBI in pregnant women, compare to the tuberculin skin test (TST). Methods: It was a cross-sectional study that involved 60 pregnant women with TB contact history as a proxy for LTBI and 30 pregnant women without contact history. Latent TB was detected using the TST 5 tuberculin units and IGRA using the QuantiFERON Gold Plus TB Test kit (QFT-Plus). The sensitivity and specificity of the two diagnostic methods and the agreement between them were estimated using SPSS version 20.0. Results: The sensitivity 95% (95% confidence interval [CI]: 86.08%–98.96%) and specificity 26.7% (95% CI: 12.28%–45.89%) of TST were compared to that of the IGRA with 60% (95% CI: 46.54%–72.44%) and 73.3% (95% CI: 54.11%–87.72%) sensitivity and specificity, respectively in detecting LTBI in pregnancy. Although there was a significant difference (P < 0.05) between TST and IGRA, the agreement was fair (kappa 0.39; 95% CI: 0.24–0.45). Conclusion: TST assay is more sensitive than IGRA; however, the specificity of IGRA was superior to the TST method. In this study, a fair agreement of TST and IGRA was observed for detecting latent TB infection in pregnant women with household contact with TB patients.

Keywords

• interferon-gamma release assay
• latent tuberculosis
• pregnancy
• tuberculin test