FW: EIN epi: Quantiferon grey-zone (2)

[Maffei, Joanne]

FYI

 

From: Emerging Infections Network [mailto:e...@uiowa.edu]
Sent: Monday, October 14, 2013 7:11 AM
To: EIN
Subject: EIN epi: Quantiferon grey-zone (2)

 

ORIGINAL MESSAGE:

Has anyone had problems with weakly positive Quantiferon results? Our lab is suggesting we use a grey-zone (referring to the Quantiferon gold) for TB-nil results of 0.3-0.7 and they recommend that we repeat results that come up in that range. This is based on some data about the poor reproducibility of the test in that grey-zone area.
My concern with having a "made up" grey-zone includes medicolegal, logistic and financial issues in addition to the obvious clinical implications of having people interpreting this test the wrong way. My practical side tells me that people just want black or white results, not grey-zones. Any thoughts?
Emilio V. Perez-Jorge, MD, West Columbia, SC

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Date: Fri 11 Oct 2013 08:59
From: Burke, Timothy L. <Timoth...@EssentiaHealth.org>

We have used this IGRA for several years and have definitely seen low positives in people with no risk factors for TB. We often repeat the test in one month and most repeat results are negative. We do not diagnose LTBI or recommend treatment when individuals with no risk factors have discordant results. Our service area (NE MN, NW WI) is low prevalence so I’m not sure how this approach would work in a higher prevalence region.

Timothy Burke, MD
Essentia Health
Duluth, MN

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Date: Fri 11 Oct 2013 11:03
From: Ken.X...@kp.org

On most repeat assays, the result is either negative or positive.

Ken Purdy, MD
Santa Clara, CA

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Date: Mon 14 Oct 2013 07:00
From: Infectious Disease <inf...@SpringfieldClinic.com>

This is a huge problem. Our transplant service won’t “accept” values less than 1.0. I saw a 50 year old man in October 2012 for dental abscess. He had a 25mm PPD in jail in 1999 and received INH for one year. In June 2012 his very compulsive PCP ordered a Quantiferon test which was <0.35. We see discrepancies all the time.

Don Graham, M.D.
Springfield Clinic
Springfield, IL

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