Influence of Age and Nutritional Status on the Performance of the Tuberculin Skin Test and QuantiFERON®-TB Gold In-Tube in Young Children Evaluated for Tuberculosis in Southern India.

Background: Reliable identification of Mycobacterium tuberculosis infection or tuberculosis (TB) disease in young children is vital to assure adequate preventive and curative treatment. The tuberculin skin test (TST) and IFN[gamma]-release assays may supplement the diagnosis of pediatric TB as cases are typically bacteriologically unconfirmed. However, it is unclear to what extent the performance of TST and QuantiFERON-TB Gold In-Tube (QFT; Cellestis’ IFN[gamma]-release assay test) depends on the demographic, clinical and nutritional characteristics of children in whom they are tested. Methods: During a 2-year prospective observational study of 4382 neonates in Southern India, children with suspected TB were investigated and classified by a standard TB diagnostic algorithm. Results: Clinical TB was diagnosed in 13 of 705 children referred for case verification with suspected TB. TST and QFT had a susceptibility for clinical TB of 31% and 23%, respectively, in this group. Children <2 years were more likely to test QFT indeterminate. A height-for-age Z score within the lowest quartile increased the odds ratio (OR) for a positive or indeterminate QFT result [OR 2.46 (1.19–5.06), OR 3.08 (1.10–8.58)], whereas the OR for a positive TST was reduced with a weight-for-height Z score within the lowest quartile [OR 0.17 (0.06–0.47)]. Conclusion: The sensitivities of the TST and QFT for clinical TB in children