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QuantiFERON®-TB Gold Plus (QFT-Plus)

QUANTIFERON-TB GOLD Plus (FOR TB SCREENING)

QuantiFERON®-TB Gold Plus (QFT-Plus) is a simple blood test that aids in the detection of Mycobacterium tuberculosis, the bacteria which causes tuberculosis (TB). Like its predecessor, QFT-Plus is an interferon gamma release assay, commonly known as an IGRA, and is a modern alternative to the tuberculin skin test (TST).

How is the test performed?

A simple blood test
how to order

FAQs

What is the QuantiFERON®–TB Gold Plus test?

QuantiFERON®–TB Gold Plus (QFT-Plus) is a simple blood test for Tuberculosis (TB), an air-born and highly contagious infectious disease.

While TB most frequently affects the lungs (pulmonary TB) it can also cause disease in any part of the body, such as the lymph nodes, bones, brain, organs and eyes. TB is a serious disease that kills about 1.5 million people each year worldwide.

TB is spread when a person with active, infectious TB disease coughs, sneezes, or spits, releasing droplets containing TB bacteria into the air, which are then inhaled by someone else.

What is latent TB?

Not everyone who is exposed to TB bacteria will develop an infection, and not all of those who become infected will develop symptoms of TB disease, which is why getting tested is so important. Those who are infected but have no symptoms are said to have a latent TB infection (LTBI), while those who do become sick have an active infection.

 If you have latent TB, you do not feel sick but you could become sick at some point if your LTBI becomes an active TB infection. This happens to about 10% of people with untreated latent TB infections, who are otherwise in good health. A greater percentage of people with compromised immune systems, such as those suffering from malnutrition, tobacco users, those with diabetes, and especially those with HIV infection, are at greater risk of developing active TB disease.

What makes QFT-Plus better than the skin test?

With the QFT test you only need to visit LifeLabs once to give a blood sample.

With the skin test, you need to plan two visits to your healthcare provider: one to administer the test and one to check for results.

The QFT-Plus test is better at helping your healthcare provider determine  if you have TB, saves you time, and provides more accurate results than traditional skin prick testing.

 There are no risks to getting this test done. All you need to do is get blood drawn at a select LifeLabs location in your province.

Who should have the QFT-Plus test?

QFT-Plus can be used in place of the skin test and is suitable for anyone who has:

  1. Had contact with someone known to have TB
  2. Been to a country with high rates of TB
  3. A weak immune system, such as:
    1. Those with HIV infection
    2. Those with chronic underlying conditions, including diabetes and kidney disease
    3. Organ transplant recipients and others on immunosuppressant drugs
    4. Pregnant women
    5. The elderly
  4. Started some types of medications

Additionally, people who work with, or are part of groups with high rates of infection, such as IV drug users, or confined populations, such as hospitalized patients, prisoners, and residents of nursing homes can also use this test.

QFT-Plus works in people who have been previously vaccinated against TB, and can also be used to confirm a positive skin test result.

Is there a charge for this test?

The fee for this test is C$104.00. It is not covered by the provincial health insurance plans, but it may be covered by extended health insurance plans.

How can I get the QFT-Plus test?

QFT is available at select LifeLabs locations in Ontario and BC.  You must bring a completed test requisition from your healthcare provider.

QFT is available at select LifeLabs locations in Ontario and BC.  You must bring a completed test requisition from your healthcare provider.

An appointment is required to complete this test as it requires specialized staff and/or specific medical equipment. To book your appointment, please visit our location finder and select specialty test name in the Specialty Test dropdown filter when entering your search criteria.

QFT is available at select LifeLabs locations in Ontario and BC. You must bring a completed test requisition from your healthcare provider and your health card to your appointment.

What will the test show?

The QFT-Plus test will help your healthcare provider determine if you have TB. It will show one of two results:

  • Positive – you will probably have TB. However, your healthcare provider needs to see you before confirming that you have TB
  • Negative- you probably do not have TB.

Occasionally, the results are not clear. If that happens, your healthcare provider may have you take the test again.

When will I get the results?

It usually takes one to two weeks for LifeLabs to complete the test. Your healthcare provider will inform you when to expect results.

If you have any questions about latent TB or the QFT-Plus test, please speak with your healthcare provider.

Sources
  1. Qiagen, QuantiFERON®–TB Gold Plus product information
  2. World Health Organization’s Fact Sheet on Tuberculosis

FAQs

TEST AT A GLANCE

Clinical

Utility

QFT-Plus is a highly accurate, single visit IGRA test for screening potentially TB-infected patients, and accurately diagnosing Latent TB Infections (LTBI).

Ordering

In Ontario, the healthcare provider needs to indicate ‘QFT-Plus’ in the ‘Other Tests’ section of the standard MOH requisition form.

In British Columbia, the healthcare provider must order this test on the specialized, patient-pay QFT-Plus requisition form.

Patient Instructions

Patient needs to bring the completed requisition form to a Patient Service Centre.

Turnaround

Time

Test results will be available within 2 weeks.

Cost

This test is not currently covered by provincial health plans, but may be covered by the patient’s private insurance.
What is QuantiFERON®–TB Gold Plus?

QuantiFERON®–TB Gold Plus (QFT-Plus) is the updated version of the QuantiFERON®–TB Gold (QTF) test.

Like its predecessor, QFT-Plus is a simple blood test that aids in the diagnosis of exposure to Mycobacterium tuberculosis, the bacteria which causes tuberculosis (TB). QFT-Plus is an interferon gamma release assay, commonly known as an IGRA, and is a modern alternative to the tuberculin skin test (TST). Unlike the TST, QFT-Plus is a controlled laboratory test that requires only one patient visit and works on patients who have previously been vaccinated against TB with the Bacille Calmette-Guerin (BCG) vaccination.

Compared to QFT, the QFT-Plus test is optimized with innovative TB-specific antigens that elicit both CD4 and CD8 T cell responses – giving a more comprehensive assessment of the patient’s immune response to TB infection.

What is being tested?

Along with accurately detecting active TB, QFT-Plus also diagnoses Latent TB Infection (LTBI) which is an asymptomatic infection, and is believed to affect over one-quarter of the global population. LTBI is a state of persistent immune response with evidence of clinically active TB. Approximately 5-15% of infected individuals will progress to active TBI if not diagnosed and treated. This progression is called the reactivation of LTBI.

QFT-Plus measures the amount of interferon gamma that is released when infected white blood cells in a blood sample come into contact with specific antigens of M. tuberculosis. The test is simple, fast and considered the most clinically tested and proven. The use of whole blood in QFT-Plus makes T cell incubation simple and fast, and reduces turn-around time (TAT). It is simple as there is no lymphocyte isolation, washing, counting, diluting, or culturing.

When is the test ordered?

The QFT-Plus Test can be used be used for individuals who:

  • Have had contact with persons diagnosed with active pulmonary TB,
  • Are at increased risk of progression to active TB disease due to impaired immunity,
  • Have radiographic evidence of old, healed TB without history of treatment and
  • Have an increased risk for LTBI due to injection-drug use.

Additionally, the following individuals should be screened for tuberculosis:

  • Foreign-born persons and visitors from TB-endemic countries, especially immigrants who have arrived in the last two years
  • Residents and employees of prisons and jails
  • Individuals eligible for LTBI surveillance programs such as health-care workers, aid workers and military personnel
  • Screening for LTBI is viewed as precautionary in management of patients with the following inflammatory diseases: rheumatoid arthritis, ulcerative colitis, psoriasis and psoriatic arthritis, ankylosing spondylitis, and Crohn’s disease.

The QFT-Plus test works on patients who have previously been vaccinated against TB with the Bacille Calmette-Guerin (BCG) vaccination. QFT-Plus requires only one patient visit to a LifeLabs location, has a high sensitivity (>94%) and high specificity (>97%) which reduces unnecessary evaluations (labs, X-rays).

QFT is approved by both FDA and Health Canada as a diagnostic test to detect Mycobacterium tuberculosis infection.

What’s on the results?

The whole blood sample is collected in 4 specialized tubes that enable immediate exposure of the white blood cells to highly specific TB antigens (ESAT-6, CFP-10 and proprietary CD8 antigens). Only 1 ml of whole blood is required per tube.

The QFT-Plus results are reported qualitatively as negative or positive for the bacteria, as well as quantitatively with a numerical value (reported in IU/mL). The numerical value indicates the amount of interferon gamma that is released when infected blood cells are exposed to specific antigens of M.tuberculosis.

In healthy persons who have a low likelihood both of M. tuberculosis infection and of progression to active tuberculosis if infected, a single positive QFT-Plus result should not be taken as reliable evidence of M. tuberculosis infection. Repeat testing, with either the initial test or a different test, may be considered on a case-by-case basis.

How do I order this test?

In Ontario, the test may be ordered on the standard OHIP requisition. In BC, a specific QFT-Plus requisition is required to be filled and signed by the healthcare provider. Your patient must bring the requisition form signed by you to one of our locations.

Please note that this test is offered in select LifeLabs locations only. To order this test for your patient, please advise them of the price (C$104.00) and have them book an appointment at one of our select locations, listed below. listed below. 

The QFT test is available in select LifeLabs locations in Ontario & BC. Please refer to the link for more details.

The QFT test is available in select LifeLabs locations in Ontario & BC. Please refer to the link for more details.

To book a QFT test appointment, patients can visit our Location Finder and use the specialty test dropdown filter to find a LifeLabs location that offers QFT test appointments near them.

Sources
  1. Qiagen, QuantiFERON®–TB Gold Plus product information
  2. Pai et. al. Canadian Tuberculosis Standards 7th Edition: 2014 – Diagnosis of latent Tuberculosis infection
  3. Centers for Disease Control and Prevention, Guidelines for Using the QuantiFERON®-TB Test for Diagnosing Latent Mycobacterium tuberculosis Infection, 2012
  4. CDC. Updated guidelines for using gamma release assays to detect m. tuberculosis infection. MMWR. 2010;59(RR05):1-25
  5. City of Toronto, Tuberculosis Information for Healthcare Providers: Management of Latent Tuberculosis Infection and Active Disease – Information for Health Professionals
  6. Latent tuberculosis infection: An overview – CCDR: Volume 43-3/4, March 2, 2017: Tuberculosis (TB)
  7. World Health Organization’s Fact Sheet on Tuberculosis

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