Diagnosis of latent tuberculosis infection among pediatric household contacts of Iranian tuberculosis cases using tuberculin skin test, IFN- γ release assay and IFN-γ-induced protein-10

QuantiFERON-TB Gold Plus Performance in Children: A Narrative Review

This review summarizes studies evaluating the performance of the QuantiFERON-TB Gold Plus (QFT-Plus) interferon-gamma release assay (IGRA) test for Mycobacterium tuberculosis ( Mtb ) infection in children. Literature searching was conducted using PubMed, MEDLINE and Embase (January 2017 to December 2021) and the terms "children" or "pediatric" and "IGRAs" or "QuantiFERON-TB Gold Plus." Selected studies (N = 14; 4646 subjects) enrolled children with Mtb infection, tuberculosis (TB) disease or healthy children with household TB contacts. Agreement between QFT-Plus and tuberculin skin test (TST) (kappa values) ranged from -0.201 (no agreement) to 0.83 (almost perfect agreement). Assay sensitivity of QFT-Plus (against reference standard of microbiologically confirmed TB disease) was 54.5%-87.3%, with no reported difference in children less than 5 versus greater than or equal to 5 years of age. In individuals less than or equal to 18 years of age, the rate of indeterminate results was 0%-33.3% (2.6% in children <2 years). IGRAs may overcome the limitations of TST in young, Bacillus Calmette-Guérin-vaccinated children.

Interferon-Inducible Protein-10 as a Marker to Detect Latent Tuberculosis Infection in Patients with Inflammatory Rheumatic Diseases

It is important to identify cases of latent tuberculosis infection (LTBI) who are at risk for tuberculosis (TB) reactivation. We aimed to evaluate the performance of interferon (IFN)-gamma-inducible protein 10 (IP-10) as a marker to detect LTBI in patients with inflammatory rheumatic diseases (IRD). This study comprised 76 consecutive subjects with IRD. Patients with a history of TB or having active TB were excluded. In all patients, IP-10 level was measured and tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube test (QFT-GIT) were performed. Seventy patients with complete test results were analyzed. Twenty-one (30%) QFT-GIT-positive patients were defined as having LTBI. IP-10 yielded 2197 pg/mL cut-off point. At this cut-off point, IP-10 showed 89% specificity with a sensitivity of 91% (AUC: 0.950, 95% CI 0.906–0.994). TST, QFT-GIT, and IP-10 were positive in 77.1%, 30%, and 44.3% of the patients, respectively. Concordance among the results of TST, QFT-GIT, and IP-10 tests was evaluated. Agreement was poor between IP-10 and TST (58.6%, κ = 0.19), whereas it was good between QFT-GIT and IP-10 (84.3%, κ = 0.65). The results of the present study demonstrated that sensitivity and specificity of released IP-10 were as high as those of QFT-GIT in indicating LTBI in IRD patient group.