TITLE:
What Tool for Diagnosis of Latent Tuberculosis Infection in Developing Country with Tuberculosis High Burden: Interferon Gamma Release Assays versus Tuberculin Skin Test in Burkina Faso
AUTHORS:
Diakourga Arthur Djibougou, Gloria Ivy Mensah, Tibila Kientega, Leon Tinnoaga Sawadogo, Hervé Hien, Clément Ziemlé Meda, Adrien Marie-Gaston Belem, Roch Konbobr Dabiré, Bassirou Bonfoh, Kennedy Kwasi Addo, Potiandi Serge Diagbouga
KEYWORDS:
LTBI Diagnosis, IGRA, TST Threshold, Concordance, Burkina Faso
JOURNAL NAME:
Advances in Infectious Diseases,
Vol.12 No.4,
November
3,
2022
ABSTRACT: Background: The diagnosis and treatment of active tuberculosis and the detection/management of latent tuberculosis infection (LTBI) cases are the two main strategies for the TB control, particularly in endemic countries. Tuberculin skin test (TST) and Interferon Gamma Release Assays (IGRAs) are tools for detection of LTBI. The objective of this study was to evaluate the performance of the TST and QuantiFERON-TB Gold Plus® (QTF-Plus) and to identify a threshold for TST in best agreement with QTF-Plus for LTBI detection in a high TB burden setting. Methods: In July 2020, a cross-sectional analytical study was performed for QFT-Plus using blood samples and TST in 101 individuals with a high risk of TB living in Bobo-Dioulasso, Burkina Faso. A crude comparison between both tests was done and receiver operating characteristic curve was generated to determine TST’s threshold. TST sensitivity, specificity, predictive values and accuracy were calculated. Adjusted agreement between TST and QFT-Plus was evaluated. Results: With the minimum threshold of positivity set at 5 mm for TST, the overall agreement between the latter and QFT-Plus was poor with a Kappa coefficient (κ) rated at 0.319 (95% CI: 0.131 - 0.508). This cut-off yielded a sensitivity of 94.12% (95% CI: 88.53 - 99.71), and very poor specificity of 36.4% (95% IC: 25.0 - 47.80). However, an adjusted cut-off set at 11 mm gave a better specificity of 72.73% (95% CI: 62.1 - 83.30) of TST and improved the PPV (86%). Moreover, concordance between both tests was improved with κ at 0.56 (95% CI: 0.385 - 0.728) and 80.20% of accuracy. Factors associated with discordance between TST (11 mm) and QFT-Plus results were BCG vaccination, OR = 7.53 (95% CI: 1.43 - 139.25), p = 0.05 and chronic cough, OR = 5.07 (95% CI: 1.27 - 20.43), p = 0.01. Conclusions: This study showed that using a minimal cut-off of 11mm for TST significantly improved the concordance between QTF-Plus (IGRA) and TST. Using the cut-off TST of 11 mm would be ideal in low-income countries with a high TB burden, taking into account factors that could contribute to the discrepancy of results.