Utility of tuberculin skin test and IGRA for tuberculosis screening in internationally adopted children: Retrospective analysis from a single center in Florence, Italy

Background: Most of internationally adopted children (IAC) come from countries in which tuberculosis (TB) is endemic. Interpretation of discordant Tuberculin Skin Test (TST) and Quantiferon-Gold In Tube (QFT) results is under debate. Methods: Children consecutively referred to our IAC Center between 2009-2017 were prospectively evaluated and screened with protocol recommended by the America Academy of Pediatrics, including TST and QFT. TB infection prevalence was evaluated and possible risk factors associated with discordant TST/QFT results were investigated. Results: 1775 IAC were enrolled (median age: 5.8; IQR:3.3-8.2; 1065 [60.0%] males). Most of the children came from a European country (715; 40.3%) and, among them, 428 (59.9%) from Russia. Active pulmonary TB was diagnosed in 7 (0.4%) children while LTBI was diagnosed in 255 (14.4%) children. Concordant TST-/QFT-result was observed in 1520 (85.6%) children, concordant TST+/QFT + result in 63 children (3.5%), while 169 children (9.5%) displayed TST+/QFT-result and the remaining 23 children (1.3%) TST-/QFT+. Factor significantly associated with discordant TST+/QFT-result was BCG vaccination (aOR:2.62; 95%CI. 1.12-6.12; P = 0.026) and age < 5 years (aOR: 5.59; 95%CI:2.27-12.18; P < 0001).. No significant association was evidenced with, continent of origin, eosinophilia or gender. Conclusions: Our data suggest that QFT might be used as unique screening assay in IAC, but further studies are needed at this regard.