Comparison of T-SPOT.TB assay and tuberculin skin test for the evaluation of young children at high risk for tuberculosis in a community setting

Abstract

Objective: We wished to compare the sensitivity of an enzyme-linked immunospot assay (T-SPOT.TB; Oxford Immunotec, Oxford, United Kingdom) and the tuberculin skin test for the detection of tuberculosis infection in very young children being evaluated for active tuberculosis in a rural community setting.

Methods: Children with a history of exposure to tuberculosis and children presenting to a local clinic or hospital with symptoms suggesting tuberculosis were admitted to a dedicated case verification ward. T-SPOT.TB testing was performed, and children were evaluated with a clinical examination, a tuberculin skin test, chest radiographs, and cultures of induced sputum and gastric lavage specimens. The diagnosis was determined by using a clinical algorithm.

Results: A total of 243 children (median age: 18 months) were recruited, of whom 214 (88%) had interpretable T-SPOT.TB results. Children > or =12 months of age were more likely than younger children to have positive T-SPOT.TB results, whereas tuberculin skin test results were unaffected by age. The sensitivity of the T-SPOT.TB was no better than that of the tuberculin skin test for culture-confirmed tuberculosis (50% and 80%, respectively) and was poorer for the combined group of culture-confirmed and clinically probable tuberculosis (40% and 52%, respectively). For the 50 children clinically categorized as not having tuberculosis, the specificity of both the T-SPOT.TB and the tuberculin skin test was 84%.

Conclusions: For young children presenting in a community setting after exposure to tuberculosis or with symptoms suggesting tuberculosis, T-SPOT.TB cannot be used to exclude active disease. The sensitivity of this assay may be impaired for very young children.