Indeterminates? They're a bad thing, right?

Not really.


You have probably noticed that the Diel Meta Study quotes the indeterminate figure for QFT.

The pooled rate for all populations of indeterminate results was low, 2.1 percent

All this means is that in 2.1% of cases QFT was unable to provide a clear YES/NO answer to the question - "Does this patient have TB?". 


Clearly we are really after results. So, we do want as low an indeterminate rate as possible (2.1% is low, very low). However, the story does not end there. An indeterminate result is still a result - it still tells you something. It tells you that we don't know if the patient has TB - they might and they might not have.


Compare that with the currently used skin test. It has no provision for indeterminates. If it can't diagnose TB then it just gives a negative result that is indistinguishable from a true negative. This has two repercussions.


1. It may mean that patients that have potentially infectious TB may be given a (false) clean bill of health and sent off into society to possibly infect other people at some time in the future; and


2. It places all negative results from the skin test in some doubt. How do you tell the difference between a true negative and a false negative? You can't.


Neither of these situations need arise with the use of QFT. 


This whole indeterminate thing is often overlooked.