some light reading, page-18

more reading....

setback for T SPOT
SOUTH AFRICA: 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

Pediatrics Vol. 123; No. 1: P. 38-43 (01..09) - Wednesday, February 04, 2009
Mark P. Nicol, FCPath, PhD; Mary-Ann Davies, MBChB; Kathryn Wood, Nat Dip; Mark Hatherill, MD, FCPaed; Lesley Workman, RN; Anthony Hawkridge, MBChB, FCPHM; Brian Eley, MBChB, FCPaed; Katalin A. Wilkinson, PhD; Robert J. Wilkinson, FRCP, PhD; Willem A. Hanekom, MBChB, FCPaed; David Beatty, FCPaed, PhD; Gregory Hussey, FCPaed, PhD
The study authors sought to compare the sensitivity of an enzyme-linked immunospot assay (T-SPOT.TB; Oxford Immunotec, Oxford, UK) and the tuberculin skin test for the detection of TB infection in very young children being evaluated for active TB in a rural community setting.

Children with a history of TB exposure and those presenting to a local health care facility with symptoms suggesting TB were admitted to a dedicated case verification ward. T-SPOT.TB testing was performed, and the children were evaluated with a clinical exam, a TB skin test, chest X-ray, and cultures of induced sputum and gastric lavage specimens. A clinical algorithm was employed to determine the diagnosis.

Of the 243 children (median age: 18 months) recruited, 214 (88 percent) had interpretable T-SPOT.TB results. Children age 12 months or older were more likely to have positive T-SPOT.TB results than younger children; however, TB skin test results were unaffected by age. For culture-confirmed TB, the sensitivity of the T-SPOT.TB was no better than that of the TB skin test (50 percent and 80 percent, respectively); it was poorer for the combined group of culture-confirmed and clinically probable TB (40 percent and 52 percent, respectively). In the 50 children clinically categorized as not having TB, the specificity of both the T-SPOT.TB and the TB skin test was 84 percent.

"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 authors concluded. "The sensitivity of this assay may be impaired for very young children."