A Stanford investigator and his colleagues found that a screening test for tuberculosis was a good predictor of whether children infected with the bacteria would become sick.
A simple blood test commonly used in screening adults for tuberculosis could predict whether children infected with the TB bacteria are likely to progress to the active disease, according to a study by researchers at the Stanford University School of Medicine and five other institutions.

In an analysis of medical data from more than 2,500 South African babies, infectious disease specialist Jason Andrews, MD, and his colleagues found that a test, known as the QuantiFERON–TB assay, was a valuable predictor of which infants carrying the bacteria would become sick. The test could be particularly useful in high–risk countries like South Africa, where hundreds of thousands of young children die of the disease every year and where screening tests for TB in children are ineffective, Andrews said.

“It could be highly valuable in determining which kids will develop TB disease,” said Andrews, an assistant professor of medicine who is lead author of the study.

Andrews said he hopes the study will prompt changes in World Health Organization guidelines, which currently don’t recommend use of the test in children.

“Given the high rates of TB and the difficulty of diagnosing it in kids, this can be something that could be done routinely in kids to identify the high–risk ones,” he said. “You could imagine in a high–burden country that at a child’s 12–month visit, they could also get a QuantiFERON test and, if it’s high, they’d get aggressively investigated for TB.”

The test is a type of interferon–gamma release assay, or IGRA, commonly used for TB screening, both here and abroad, as it is more accurate than the older skin test.

“These new findings confirm that the IGRA test for tuberculosis infection performs differently in young children compared with adults,” said Mark Hatherill, MD, senior author of the study and senior clinical researcher at the South African Tuberculosis Vaccine Initiative. “More importantly, we now know that the IGRA test can be used to identify those children who are at highest risk of developing tuberculosis disease and who would benefit most from investigation and therapy.”

The study was published online Feb. 10 in Lancet Respiratory Disease journal.