Dr Masae Kawamura, from the San Francisco Department of Health, is the presenter.
The title page is here, the presentation can be viewed online here and can also be downloaded here
It is a comprehensive presentation so I will just concentrate on one particular section
Accompanying this particular slide Dr Kawamura makes the following comments;
When you switch to IGRAs you can expect the following: TB programs in San Francisco and New York City using QFT in very high volumes have seen a significant decrease - by about two thirds - in the number of positive results when compared to using the skin test. This has meant a significant decrease in further work up and LTBI treatment. In contrast, we have seen a curiosity that has sometimes led to unnecessary testing and retesting. Our golden rule is, "if the IGRA result is not going to change what you do, please do not order the test!"To my mind the presentation is subtly laying down a challenge; IGRAs are only for those who want to change - do you want to change? For those in the TB industry who are happy to continue with the status quo of dubious diagnoses and for those to whom TB testing is just a requirement - the TST will meet those needs. Without an intention to proceed further the diagnosis has little relevance. Therefore it is imperative that guidelines stress that Decision to Test is Decision to Treat!
When using IGRAs in serial testing, you will again find more negative results compared to the TSTs, but you may also experience a higher rate of "IGRA converters." This could require further investigation that includes repeating the IGRA and reviewing the quantitative results to look for what some experts call "wobblers." These are individuals who have results that hover around the cut point, sometimes above and sometimes below, and their negative-to-positive result may not be true conversion.
The requirement to treat throws the responsibility back on to the examiner, which diagnostic is the better?
