Rog
Much as I think QFT G or QFT IT is a wonderful test, I think something is getting lost in the translation in this article from Iran
They cannot say: “it may be useful for the diagnosis of both LTBI and active TB, without the need for other tests.”
If you start with just a positive QFT test for Tuberculosis then it could be Latent Tb or Active Tb to explain the test, but the patient might have lung cancer and latent Tb, or ordinary pneumonia and latent Tb.
You have to do at least a chest Xray, and probably other tests to make sure it isn’t active Tb (by definition you have to show the Tb organism) and at the same time to show that it is another diagnosis (show the lung cancer or the other cause for pneumonia).
Not only that if you are looking for the diagnosis of active Tb and the QFT test for Tb is negative - then they are forgetting that in up to 20% of cases of active Tb – QFT can still be negative. (It is an extremely good test for latent Tb depending on how you set your gold standard).
I think the way some of these articles are written, caution is needed in their literal interpretation. That’s where guidelines cause problems as they look inflexible whereas in practice, medicine is often a skill and an art that brings together all of the information to make the diagnosis and manage the patient.
skorpian
