Retrospective evaluation of the results of immunodiagnostics for tuberculosis in children

Introduction. For early immunodiagnostics of tuberculosis (TB) in Russia, the Mantoux test (MT) has been used for decades; since 2013, the recombinant tuberculosis antigen (RTA) test has seen widespread use. The objective of this retrospective analytic observational cohort study was to evaluate the results of immunodiagnostics for TB in children with newly diagnosed active TB. Materials and methods. We studied data from Russian TB institutions on the results of MT and RTA assay in children with active and inactive TB first detected in 2013–2018, as well as children with active TB first detected in Moscow in 2017–2022. Results and discussion. In 2013–2018, out of 12,902 examined children with active TB, 11,673 (90.5%) had positive results of both skin tests and 198 (1.5%) had negative results. A negative RTA assay result with positive MT was found in 861 (6.7%) patients, and a positive RTA assay result with negative MT in 170 (1.3%). The sensitivity of the RTA assay in detecting active TB was 91.3%, while the sensitivity of MT was 97.2% (p 0.01). Similar data were obtained in the same regions in 14,127 children with inactive TB: the sensitivity of MT was higher than that of the RTA assay — 97.2% versus 95.2% (p 0.01). In Moscow, due to the small number of observations in 2022, it was not possible to show statistical reliability of the difference between the sensitivity of MT and RTA assay in detecting active TB in 2017–2022 (95.8% and 92.1% respectively; p 0.5). For the results obtained in 2017–2021, the difference was significant (p 0.05). Conclusion. The sensitivity of MT is higher than that of the RTA assay in screening children for TB. It is recommended to use the more sensitive MT test for screening children; screening with the RTA assay will increase the number of undetected and undiagnosed cases of active TB in children. Currently, MT cannot be excluded from the algorithm of early TB diagnosis in children.