New Blood Test for Tuberculosis in BCG-Vaccinated People
Author Information
Author(s): Roland Diel, Albert Nienhaus, C. Lange, K. Meywald-Walter, M. Forßbohm, T. Schaberg
Primary Institution: School of Public Health, University of Düsseldorf, Germany
Hypothesis
How well do TST and QFT-G results correlate and what are the presumed reasons for divergent results?
Conclusion
The QFT-G assay was unaffected by BCG vaccination status, making it a more specific indicator of latent tuberculosis infection than the TST in BCG-vaccinated individuals.
Supporting Evidence
- The overall agreement between the TST and the QFT-G was low (κ = 0.2).
- In BCG-vaccinated close contacts, the QFT-G assay was a more specific indicator of latent tuberculosis infection than the TST.
- Only 10% of contacts showed a positive QFT-G result compared to 44.3% for the TST.
Takeaway
A new blood test can better tell if someone has latent tuberculosis, especially if they've had the BCG vaccine, compared to the old skin test.
Methodology
The study compared the TST with a specific blood test (QFT-G) among close contacts of tuberculosis cases over a 6-month period.
Potential Biases
Potential bias due to reliance on self-reported vaccination status and exposure history.
Limitations
The study was limited to a specific population in Hamburg and may not be generalizable to other settings.
Participant Demographics
Mean age of participants was 28.5 years, with 50.8% previously BCG vaccinated and 27.2% foreign-born.
Statistical Information
P-Value
p<0.0001
Confidence Interval
95% CI 0.14–0.23
Statistical Significance
p<0.05
Digital Object Identifier (DOI)
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