Risk factors associated with positive quantiFERON-TB gold in-tube and tuberculin skin tests results in Zambia and South Africa

• Main Authors: Shanaube, Kwame, Hargreaves, James, Fielding, Katherine, Schaap, Ab, Lawrence, Katherine-Anne, Hensen, Bernadette, Sismanidis, Charalambos, Menezes, Angela, Beyers, Nulda, Ayles, Helen, Godfrey-Faussett, Peter
• Format: Others
• Language: en_ZA
• Published: Public Library of Science (PLOS) 2011
• Subjects: South Africa > Medical policy; Zambia > Medical policy; QuantiFERON-TB Gold In-Tube (QFT-GIT) > Therapeutic use; Tuberculosis > Diagnosis > Zambia; Tuberculin skin test > Therapeutic use; Tuberculosis > Diagnosis > South Africa; Tuberculin skin tests > Risk factors; Tuberculous infections > Vaccination; Tuberculosis > Risk factors
• Online Access: http://hdl.handle.net/10019.1/11596

The original publication is available at http:/www.plosone.org === Introduction: The utility of T-cell based interferon-gamma release assays for the diagnosis of latent tuberculosis infection remains unclear in settings with a high burden of tuberculosis. Objectives: To determine risk factors associated with positive QuantiFERON-TB Gold In-Tube (QFT-GIT) and tuberculin skin test (TST) results and the level of agreement between the tests; to explore the hypotheses that positivity in QFT-GIT is more related to recent infection and less affected by HIV than the TST. Methods: Adult household contacts of tuberculosis patients were invited to participate in a cross-sectional study across 24 communities in Zambia and South Africa. HIV, QFT-GIT and TST tests were done. A questionnaire was used to assess risk factors. Results: A total of 2,220 contacts were seen. 1,803 individuals had interpretable results for both tests, 1,147 (63.6%) were QFT-GIT positive while 725 (40.2%) were TST positive. Agreement between the tests was low (kappa = 0.24). QFT-GIT and TST results were associated with increasing age (adjusted OR [aOR] for each 10 year increase for QFT-GIT 1.15; 95% CI: 1.06-1.25, and for TST aOR: 1.10; 95% CI 1.01-1.20). HIV positivity was less common among those with positive results on QFT-GIT (aOR: 0.51; 95% CI: 0.39-0.67) and TST (aOR: 0.61; 95% CI: 0.46-0.82). Smear positivity of the index case was associated with QFT-GIT (aOR: 1.25; 95% CI: 0.90-1.74) and TST (aOR: 1.39; 95% CI: 0.98-1.98) results. We found little evidence in our data to support our hypotheses. Conclusion: QFT-GIT may not be more sensitive than the TST to detect risk factors associated with tuberculous infection. We found little evidence to support the hypotheses that positivity in QFT-GIT is more related to recent infection and less affected by HIV than the TST. © 2011 Shanaube et al. === Publishers' Version