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【medical-news】结核筛查：干扰素γ释放试验优于结
More than half of the TB cases in the U.S. occur among immigrants, some of whom are from countries where the disease is prevalent and where BCG vaccination is commonly used. The problem for public health officials is that prior BCG vaccination can cause a high rate of false-positive results when using a tuberculin skin test, the most common tool used in the U.S. to diagnose latent TB infection.
Tests that are more specific for latent TB infection would be safer and more cost-effective, especially in high-risk immigrant populations -- those most in need of screening.
An interferon-gamma release assay can detect T-cell responses to antigens that are specific to Mycobacterium tuberculosis, yet absent from M. bovis, the basis for the BCG vaccine.
The study enrolled 96 subjects from a New York City TB clinic between September 2005 and February 2007. Subjects with active TB were excluded.
Fifty-six of the subjects were close contacts of patients with active TB, and the other 40 subjects were considered to be controls. Given the lack of a "gold standard" diagnostic test for latent TB infection, the researchers used contact status as a surrogate.
The subjects were tested with the T-SPOT.TB interferon-gamma release assay, which is currently undergoing FDA testing. (A similar interferon-gamma release assay, QuantiFERON-TB Gold, has been approved by the FDA.) All subjects had received a tuberculin skin test 6 months before.
Overall agreement between the two tests was significantly better among subjects without BCG vaccination than among those with it (p < 0.02). After adjustment for confounding factors, being a close contact was strongly associated with a positive T-SPOT.TB result (p = 0.03).
As a diagnostic tool, the T-SPOT.TB was more specific for contact status than was the tuberculin skin test, particularly among the BCG-vaccinated subjects, although the two tests had similar specificities among subjects without BCG vaccination.
In 2005, the CDC issued guidelines suggesting that interferon-gamma release assay could routinely replace tuberculin skin test in nearly any setting, Dr. Neil W. Schluger of Columbia University Medical Center told Reuters. "I think that since 2005, if anything, there is even stronger evidence that interferon-gamma release assay could and largely should replace skin testing, especially in populations where many people have received the bacille Calmette-Gurin vaccine." [标签:content1][标签:content2]
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作者:admin@医学,生命科学 2011-01-05 17:14
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