Abstract
Objectives: To estimate the concordance between the Tuberculin skin test (TST) and Quantiferon TB Gold In-tube, (QFT) among health professional trainees at a referral hospital in India, and to evaluate risk factors associated with discordant results.
Methods: From November 2009 to February 2011, students registered in various health professional programs (with the exception of medical and nursing students) were approached to participate. In addition to a questionnaire on TB exposure, participants underwent TST (10 mm cutoff) and the QFT-GIT (0.35 IU/ml cut off).
Results: 164 students completed. Mean age was 21.5 yrs (Range: 17-34), 48.8% were female and 59.15% had BCG scars. Mean time in health care was 11.5 months, and 21.6% recalled direct contact with PTB. Prevalence of LTBI by TST or QFT was 48.2% and 23.2% respectively. Agreement between tests was 71.3% (kappa=0.415). The predominant discordance was TST +/QFT- (43/164, 26.2%). Using multivariate logistic regression we evaluated whether discordant results were associated with any particular risk factors, including: age, sex, education, family income, time in health care setting, days spent in high risk wards, performing high risk procedures, pre-existing medical illness, BCG, and known TB exposure. No factors were associated with discordant results, however, age was associated with concordant positives (OR=1.27, 95%CI: 1.03-1.59), and higher family income was protective (OR=0.67, 95%CI:0.45-0.99).
Conclusions: There was fair to weak agreement between TST and QFT in this population. Concordant positives were associated with older age, and lower family income. Discordant results were not associated with any known risk factors.
- © 2011 ERS
