Delineating a Retesting Zone Using Receiver Operating Characteristic Analysis on Serial QuantiFERON Tuberculosis Test Results in US Healthcare Workers. Pulmonary medicine Thanassi, W., Noda, A., Hernandez, B., Newell, J., Terpeluk, P., Marder, D., Yesavage, J. A. 2012; 2012: 291294-?


Objective. To find a statistically significant separation point for the QuantiFERON Gold In-Tube (QFT) interferon gamma release assay that could define an optimal "retesting zone" for use in serially tested low-risk populations who have test "reversions" from initially positive to subsequently negative results. Method. Using receiver operating characteristic analysis (ROC) to analyze retrospective data collected from 3 major hospitals, we searched for predictors of reversion until statistically significant separation points were revealed. A confirmatory regression analysis was performed on an additional sample. Results. In 575 initially positive US healthcare workers (HCWs), 300 (52.2%) had reversions, while 275 (47.8%) had two sequential positive tests. The most statistically significant (Kappa?=?0.48, chi-square?=?131.0, P < 0.001) separation point identified by the ROC for predicting reversion was the tuberculosis antigen minus-nil (TBag-nil) value at 1.11 International Units per milliliter (IU/mL). The second separation point was found at TBag-nil at 0.72?IU/mL (Kappa?=?0.16, chi-square?=?8.2, P < 0.01). The model was validated by the regression analysis of 287?HCWs. Conclusion. Reversion likelihood increases as the TBag-nil approaches the manufacturer's cut-point of 0.35?IU/mL. The most statistically significant separation point between those who test repeatedly positive and those who revert is 1.11?IU/mL. Clinicians should retest low-risk individuals with initial QFT results?

View details for DOI 10.1155/2012/291294

View details for PubMedID 23326660

View details for PubMedCentralID PMC3544373