[MCOH-EH] [Bulk] Re: [Bulk] Re: Quantiferon gold TB test - preplacement question
Kathy Dayvault
KDayvault11 at att.net
Wed Jul 30 12:32:40 PDT 2014
I am not trying to be adversarial or offensive in my post and apologize if
it came across that way.
My post is a result of managing OHS services for a large HC facility in GA
and now serve as a TB educator.
At the HC organization, we developed a robust TB medical surveillance
program. Following up one test type with another is problematic I have faced
some of the same issues. We chose to utilize only one test type. an IGRA
test.
False positives when using Quantiferon gold are often a result of some type
of error in following the pre-analytical steps in the phlebotomy process:
1. Failure to use a waste tube when using a butterfly
2. Drawing the tubes in the right order: gray red and then purple
3. Shaking or inverting them 10 times- too much, too vigorous or not
enough might cause issues
4. Making sure the sample was incubated within the appropriate time
frame from being drawn- 16 hours.
5. And finally the appropriate incubation period before resulting out.
I have spoke with a lab manager who performed QFT in house who identified
that often a break in the pre-analytical steps was the culprit.
Is there harm in using both tests? No. but which result do you trust for
identifying latent TB?
In GA, when an individual is diagnosed with latent TB and refuses care or
treatment, they can be held legally liable if someone becomes ill as a
result of the progression of latent TB..huge concern for a healthcare
facility.. attaching the link to refusal of care. When calling the GA TB
unit, it is not unusual to speak to someone from the CDC. They are great
people to talk to and a huge resource.
http://dph.georgia.gov/sites/dph.georgia.gov/files/TB-FormLegal_3575.Ref.Eng
_2011.pdf
Thanks,
Kathy
Kathy Dayvault, RN, BSN, MPH, COHN-S/CM
Independant Occupational Health Nurse Consultant
JET Consulting
kdayvault11 at att.net
From: MCOH-EH [mailto:mcoh-eh-bounces at mylist.net] On Behalf Of Morelli,
Karen J
Sent: Wednesday, July 30, 2014 2:53 PM
To: 'MCOH/EH'
Subject: [Bulk] Re: [MCOH-EH] [Bulk] Re: Quantiferon gold TB test -
preplacement question
It is true that the the IGRA test and PPD are two separate methodologies.
And, yes, it is true that the Quantiferon is more specific. However, in the
light of the fact that there have been issues with false positive
Quantiferon results after ppd placements, I don't see the harm in placing a
PPD to gather more information. We live in a low incidence Tb area as well
and have been told that there are more incidents of false positive
Quantiferon results in low TB incident regions. The following excerpt is my
correspondence with the CDC concerning this subject:
Thank you for your inquiry to CDC-INFO. We are sorry for the delay in
responding to your e-mail. A recent high volume of inquiries has slowed our
response time. Your request for information on running quantiferon gold
after tuberculin skin test was forwarded to subject-matter experts at the
CDC Division of Tuberculosis Elimination (DTBE). We are pleased to provide
you with their response.
There is no CDC guidance, or guidance from any other expert source, that
IGRA should not be used after a tuberculin skin test at any specific point
in time; however; it is our opinion that the theoretical timing of potential
boosting bears consideration, but it does not constitute advice on whether
or not to use IGRA methods or when to use them.
There is a little evidence that boosting of the QFT-GIT may take > 3 days
after TST placement. Some investigators have reported evidence of boosting
for as long as 6 months. We do not know how long boosting of IGRAs after a
TST may last so have adopted the interval applied to clinical decisions for
serial TSTs. We think that boosting of QFT-GIT after a TST may last up to 1
year.
The related paragraph in the IGRA guidelines reads as follows
"Investigations examining the effect of PPD injection on sub-sequent IGRAs
have produced conflicting results (59,62-66); outcome differences probably
are attributable to differences in the study population (infected versus
noninfected subjects, recent versus temporally remote infection, and risk
for ongoing exposure), timing of IGRA testing after PPD injection, the IGRA
format, and the definition of boosting used. PPD injection should be
expected to boost anamnestic immune responses measured by IGRA originating
from M. tuberculosis infection, but not from BCG vaccination or in
nonsensitized persons. Additional studies examining the effect of PPD
injection on IFN-? responses are needed to define the frequency, magnitude,
induction time, and longevity of IGRA boosting following a TST."
Links to nonfederal organizations are provided as a service. Links are not
an endorsement of these organizations or their programs by CDC or the
federal government. CDC is not responsible for the content of organization
websites found at these links.
Thank you for contacting CDC-INFO. For more information, please call
1-800-CDC-INFO (800-232-4636) or visit www.cdc.gov/info.
CDC-INFO is a service of the Centers for Disease Control and Prevention
(CDC) and the Agency for Toxic Substances and Disease Registry (ATSDR). This
service is provided by Verizon and its subcontractors under the Networx
Universal contract to CDC.
----------------------------------------------------------------------------
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Thank you,
LH
Karen
From: MCOH-EH [mailto:mcoh-eh-bounces+kmorelli=emhs.org at mylist.net] On
Behalf Of Kathy Dayvault
Sent: Wednesday, July 30, 2014 2:26 PM
To: 'MCOH/EH'
Subject: Re: [MCOH-EH] [Bulk] Re: Quantiferon gold TB test - preplacement
question
They are not the same tests. You can have a negative PPD and a positive IGRA
test. you cannot use them to check each other's validity for pos or neg
response.
Thanks,
Kathy Dayvault, RN, BSN, MPH, COHN-S/CM
Independant Occupational Health Nurse Consultant
JET Consulting
kdayvault11 at att.net
From: MCOH-EH [mailto:mcoh-eh-bounces at mylist.net] On Behalf Of Morelli,
Karen J
Sent: Wednesday, July 30, 2014 2:14 PM
To: 'MCOH/EH'
Subject: [Bulk] Re: [MCOH-EH] Quantiferon gold TB test - preplacement
question
You could always do a ppd (since she had a documented negative ppd one month
ago, we would only do a one-step) to verify the accuracy of the Quantiferon.
Thank you,
Karen Morelli RN, BSN
From: MCOH-EH [mailto:mcoh-eh-bounces at mylist.net] On Behalf Of Band, Michael
DO
Sent: Wednesday, July 30, 2014 2:10 PM
To: 'MCOH/EH'
Subject: Re: [MCOH-EH] Quantiferon gold TB test - preplacement question
Sorry
Trying to type between patients.
Yes her quantiferon gold TB test was positive, neg ppd. I am worried this
is a false positive.
Michael Band DO, MS
From: MCOH-EH [mailto:mcoh-eh-bounces+mband=watsonclinic.com at mylist.net] On
Behalf Of Morelli, Karen J
Sent: Wednesday, July 30, 2014 2:07 PM
To: 'MCOH/EH'
Subject: Re: [MCOH-EH] Quantiferon gold TB test - preplacement question
I assume you meant to type that the Quantiferon is positive now after a
negative ppd one month ago. I have been monitoring the Quantiferon issue
since we had a cluster of false positives last fall (presumably due to
tube/process issues). The research I have done states that Quantiferon
could be run within a 3 day window of receiving a ppd, after that there is a
chance of getting a false positive reading on the Quantiferon (from the ppd
plant). There is no concrete "cut off" time frame that I have seen to know
when it would be okay to run a Quantiferon after a ppd. The TB expert in my
area stated that false positive Quantiferon tests have been noted up to 6
weeks after a ppd. Due to the uncertainty of when it would be okay to run a
Quantiferon after a ppd, our department has adopted a 6 months cut off time.
Thank you,
Karen Morelli RN, BSN
Eastern Maine Healthcare Systems
From: MCOH-EH [mailto:mcoh-eh-bounces at mylist.net] On Behalf Of Band, Michael
DO
Sent: Wednesday, July 30, 2014 1:41 PM
To: mcoh-eh at mylist.net
Subject: [MCOH-EH] Quantiferon gold TB test - preplacement question
Currently we are using the quantiferon gold TB test for use after a positive
ppd for preplacement.
Every once in a while a new doctor or employee are not available for a 48-72
hour ppd read so we do quantiferon instead.
Had a new doctor with a negative ppd one month ago at another facility and
her quantiferon gold is negative.
NO symptoms of active TB and no known exposures. She is in a low risk
specialty for TB exposure.
Chest xay normal
Question:
1. I read somewhere that a recent ppd can interfere with the
quantiferon gold test. Not sure if this is true?
2. What is the next step? Do we call this latent Tb? Is it worth
repeating the quantiferon gold test? Could this be a false positive?
Thanks for any help.
Michael Band DO, MS
Watson Clinic
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