CASE REPORTS - Quantiferon TB gold test: the new standard for screening of latent TB in patients with RA?

[Guest guest]

Ann Rheum Dis. 2006 Nov 24; [Epub ahead of print]

Quantiferon TB gold test: The new standard for screening of latent

tuberculosis in patients with rheumatoid arthritis?

Efthimiou P, Sood S.

New Jersey Medical School, UMDNJ, United States.

We read with interest the report by Ponce de Leon et al.1, where the authors

argued that tuberculin skin testing (TST) may not be an optimal test for the

diagnosis of latent tuberculosis infection (LTBI) in patient with rheumatoid

arthritis (RA). We would like to contribute to these findings, based on our

clinical experience with a new screening tool called the QuantiFERON TB-Gold

(QFT-G) test. While screening policies vary significantly between countries,

it is generally recommended that all patients with RA should undergo

screening for M. Tuberculosis latent infection prior to the initiation of

treatment with biologic agents, especially the tumor necrosis factor (TNF)

alpha inhibitors.2 Patients with RA may not be able to produce an adequate

delayed type hypersensitivity (DTH) reaction to tuberculin because of their

deficient cell mediated immunity.3-5 QFT-G is a whole blood,

antigen-specific, test that utilizes synthetic peptides representing two M.

tuberculosis proteins, ESAT-6 and CFP-10. After incubation for 16 to 24

hours, the amount of interferon (IFN)-gamma secreted by monocytes in

response to these antigens is measured.7 8 T-SPOT.TB, not yet available in

the US, is another antigen-specific blood test utilizing the enzyme-linked

immunospot (ELISPOT) assay technique. These new tests may be applicable to

patients with RA, where false negative TST can have adverse consequences in

patients treated with TNF inhibitors. We have identified two patients in our

rheumatology clinic that were TST negative but were subsequently diagnosed

with LTBI by the QFT-G test. Patient 1 is a 73 year-old black female who

presented with symmetric bilateral synovitis of the metacarpophalangeal

joints, was seropositive for rheumatoid factor (RF) and antinuclear (ANA)

antibodies, with radiographic evidence of inflammatory erosive arthropathy.

She was diagnosed with RA and had a negative TST. She was an incomplete

responder to methotrexate and corticosteroids and the decision was made to

initiate anti-TNF treatment. Repeat TST was again negative 2 months after

the first testing. However, she tested positive for QTB-G and is currently

completing a 9-month isoniazid/vitB6 course for LTBI. A confirmatory chest

radiography showed apical pleural thickening and upper lobe fibrosis,

consistent with previous history of primary tuberculosis. Patient 2 is a 61

year-old black male with severe erosive RA, who screened negative by TST

prior to immunosuppressive treatment. A pre-operative chest radiograph

showed mild interstitial scarring, without any pleural pathology. He

partially responded to methotrexate and became a candidate for anti-TNF

treatment. Positive QTB-G testing prompted the initiation of a 9-month

isoniazid/vitB6 course. In summary, QTB-G may be a more sensitive screening

tool for LTBI in RA patients with impaired DTH response to tuberculin.

Additional benefits include: it requires a single patient visit to draw the

blood sample, results can be available within 24 hours, it is not subject to

reader bias, and, most importantly, is not affected by prior BCG (bacille

Calmette-Guerin) vaccination.8 However, the test is not widely available yet

and careful studies comparing it to the TST are needed to validate our

findings in the RA population.

PMID: 17127686

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=PubMed & list_uids=1\

7127686

Not an MD

I'll tell you where to go!

Mayo Clinic in Rochester

http://www.mayoclinic.org/rochester

s Hopkins Medicine

http://www.hopkinsmedicine.org

[Guest guest]

I was asked by my new rheumatologist to participate in a study for a

new, blood test TB test. I wonder if this is the same one.

>

> Ann Rheum Dis. 2006 Nov 24; [Epub ahead of print]

>

>

> Quantiferon TB gold test: The new standard for screening of latent

> tuberculosis in patients with rheumatoid arthritis?

>

>

> Efthimiou P, Sood S.

>

> New Jersey Medical School, UMDNJ, United States.

>

> We read with interest the report by Ponce de Leon et al.1, where

the authors

> argued that tuberculin skin testing (TST) may not be an optimal

test for the

> diagnosis of latent tuberculosis infection (LTBI) in patient with

rheumatoid

> arthritis (RA). We would like to contribute to these findings,

based on our

> clinical experience with a new screening tool called the

QuantiFERON TB-Gold

> (QFT-G) test. While screening policies vary significantly between

countries,

> it is generally recommended that all patients with RA should

undergo

> screening for M. Tuberculosis latent infection prior to the

initiation of

> treatment with biologic agents, especially the tumor necrosis

factor (TNF)

> alpha inhibitors.2 Patients with RA may not be able to produce an

adequate

> delayed type hypersensitivity (DTH) reaction to tuberculin because

of their

> deficient cell mediated immunity.3-5 QFT-G is a whole blood,

> antigen-specific, test that utilizes synthetic peptides

representing two M.

> tuberculosis proteins, ESAT-6 and CFP-10. After incubation for 16

to 24

> hours, the amount of interferon (IFN)-gamma secreted by monocytes

in

> response to these antigens is measured.7 8 T-SPOT.TB, not yet

available in

> the US, is another antigen-specific blood test utilizing the

enzyme-linked

> immunospot (ELISPOT) assay technique. These new tests may be

applicable to

> patients with RA, where false negative TST can have adverse

consequences in

> patients treated with TNF inhibitors. We have identified two

patients in our

> rheumatology clinic that were TST negative but were subsequently

diagnosed

> with LTBI by the QFT-G test. Patient 1 is a 73 year-old black

female who

> presented with symmetric bilateral synovitis of the

metacarpophalangeal

> joints, was seropositive for rheumatoid factor (RF) and

antinuclear (ANA)

> antibodies, with radiographic evidence of inflammatory erosive

arthropathy.

> She was diagnosed with RA and had a negative TST. She was an

incomplete

> responder to methotrexate and corticosteroids and the decision was

made to

> initiate anti-TNF treatment. Repeat TST was again negative 2

months after

> the first testing. However, she tested positive for QTB-G and is

currently

> completing a 9-month isoniazid/vitB6 course for LTBI. A

confirmatory chest

> radiography showed apical pleural thickening and upper lobe

fibrosis,

> consistent with previous history of primary tuberculosis. Patient

2 is a 61

> year-old black male with severe erosive RA, who screened negative

by TST

> prior to immunosuppressive treatment. A pre-operative chest

radiograph

> showed mild interstitial scarring, without any pleural pathology.

He

> partially responded to methotrexate and became a candidate for

anti-TNF

> treatment. Positive QTB-G testing prompted the initiation of a 9-

month

> isoniazid/vitB6 course. In summary, QTB-G may be a more sensitive

screening

> tool for LTBI in RA patients with impaired DTH response to

tuberculin.

> Additional benefits include: it requires a single patient visit to

draw the

> blood sample, results can be available within 24 hours, it is not

subject to

> reader bias, and, most importantly, is not affected by prior BCG

(bacille

> Calmette-Guerin) vaccination.8 However, the test is not widely

available yet

> and careful studies comparing it to the TST are needed to validate

our

> findings in the RA population.

>

> PMID: 17127686

>

> http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

cmd=Retrieve & db=PubMed & list_uids=17127686

>

>

>

>

> Not an MD

>

> I'll tell you where to go!

>

> Mayo Clinic in Rochester

> http://www.mayoclinic.org/rochester

>

> s Hopkins Medicine

> http://www.hopkinsmedicine.org

>