School based screening for tuberculosis infection in Norway: comparison of positive tuberculin skin test with interferon-gamma release assay
2008

School Screening for Tuberculosis in Norway

Sample size: 511 publication 10 minutes Evidence: moderate

Author Information

Author(s): Winje Brita Askeland, Oftung Fredrik, Korsvold Gro Ellen, Mannsåker Turid, Ly Ingvild Nesthus, Harstad Ingunn, Dyrhol-Riise Anne Margarita, Heldal Einar

Primary Institution: Norwegian Institute of Public Health

Hypothesis

What is the prevalence of QFT positivity among TST positive children identified in school-based screening?

Conclusion

The study suggests a very low prevalence of latent tuberculosis infection among 9th grade school children in Norway.

Supporting Evidence

  • Only 9% of TST positive children had a confirmed positive QFT result.
  • QFT positivity was associated with larger TST induration and known exposure to tuberculosis.
  • Most children with positive TST reactions had indurations in the range of 6–14 mm.

Takeaway

The study found that most children who tested positive for tuberculosis using a skin test did not actually have the infection, showing that the skin test can give false positives.

Methodology

This cross-sectional study involved TST positive children from seven hospitals in Norway, who underwent a QFT test and completed a questionnaire on risk factors.

Potential Biases

Potential bias due to the involvement of multiple public health nurses in the TST screening process.

Limitations

The study may have missed some TST-positive children due to non-standardized administration or reading of TST.

Participant Demographics

Children in 9th grade (age 14-15), including first and second generation immigrants.

Statistical Information

P-Value

0.001

Confidence Interval

6.4 – 11.2

Statistical Significance

p<0.05

Digital Object Identifier (DOI)

10.1186/1471-2334-8-140

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