The Quantiferon-TB test (QFT) is a whole-blood interferon (IFN)-gamma assay for the recognition of cell-mediated immune response to Mycobacterium tuberculosis infection. It is already known as a useful diagnostic tool for the latent tuberculosis, but there is no study whether it can be also used to detect active tuberculosis (TB). So we investigated usefulness of the QFT for the diagnosis of active TB.
We prospectively studied in two tertiary care hospitals from Aug. 2004 to Feb. 2005. 54 patients clinically suspected as active TB were enrolled; 39 patients were AFB culture positive or histologically confirmed and 15 patients were not. We measured IFN-gamma response to PPD in whole blood assay.
The QFT of whole blood was positive in 25 out of 39 active TB patients and negative in 7 out of 15 non-TB patients. So the sensitivity, specificity, positive predictive value and negative predictive value of the QFT were 64.1%, 46.6%, 75.7% and 33.3%, respectively.
Our result demonstrates that the QFT in whole blood is not useful for the diagnosis of active TB in the region where TB incidence is high.
QFT in whole blood is not useful for the diagnosis of active TB in the region where TB incidence is high.
Dookyung Yang, None.