is notoriously unreliable due to false-positive and false-negative results.
Approved by the FDA in December 2004, QuantiFERON-TB GOLD is a simple,
one-step blood test that detects immune responses to specific proteins
associated with infection by Mycobacteria Tuberculosis. By finally providing
clinicians with an accurate, reliable and convenient TB diagnostic tool, the
breakthrough test is well positioned to become the new gold standard for TB
screening and control.
While the overall TB incidence in the U.S. is slowly decreasing, TB is
resurfacing in several "hot spot" metropolitan areas, such as San Francisco,
where 231 active TB cases were reported to the CDC in 2003 (13.6 per 100,000).
As an international city with large immigrant and migrant populations, as well
as a high number of individuals with immunosuppressive diseases such as
HIV/AIDS, the San Francisco metropolitan area has one of the highest TB rates
in the U.S. An untold number of individuals are infected with TB in its
dormant, or latent, phase and are at risk of developing active TB disease and
becoming highly contagious. Therefore, the accurate identification of people
with latent TB infection is important in the prevention of further spread of
"Medi-Cal reimbursement of QuantiFERON-TB GOLD is a tremendous achievement
because it opens the door for wider adoption in California, a state with
several TB 'hot spots,'" said Tony Radford, PhD, CEO of Cellestis. "The
urgent need for a new tool to more accurately identify individuals who are
infected and those who are at risk of developing tuberculosis has been
reinforced by a state that is a bellwether for the rest of the country."
QuantiFERON-TB GOLD is an in vitro diagnostic test unaffected by
subjective interpretation, previous TB vaccination and cross-reactivity with
most non-tuberculous or environmental mycobacteria. This means virtual
elimination of TST false-positive individuals normally recommended for
unnecessary and potentially harmful TB therapy. False-positive rates can be
as high as 50 percent of all TST responses (von Reyn et al. Int J. Tuberc
Lung Dis 5(12), 2001).
When compared with the TST, QuantiFERON-TB GOLD has been demonstrated to
yield dramatic cost savings in terms of medical staff time and the elimination
of common false-positive results. According to a recent study (Lambert et al.
Infection Control and Hospital Epidemiology Nov. 2003), researchers found that
the cost of running a TB control program using the TST is considerably more
expensive than the simple cost of the supplies, given the labor required to
successfully perform the TST. Specifically, costs to a hospital ranged from
$41 to $362 per employee, with the TST supplies representing less than
1.5 percent of the total cost of the program.
"After FDA approval, the California TB Controllers Association began
aggressively making the case to Medi-Cal for reimbursement of QuantiFERON-TB
GOLD, realizing the importance of this new technology," said Dr. Masae
Kawamura, TB controller for the city of San Francisco. "With large numbers of
immigrants and high risk patients served by San Francisco's county health
department, a more accurate test for TB has long been awaited. Now that
Medi-Cal has approved payment of QuantiFERON-TB GOLD, San Francisco has a real
chance of providing the public with a safer and more accurate test, without
breaking the bank. QuantiFERON-TB GOLD will eliminate the waste of precious
health resources from inaccurate skin tests and improve public safety by
preventing unnecessary treatment."
The National TB Controllers Association strongly advocates the use of
FDA-approved blood test to diagnose latent TB infection
Further support for QuantiFERON-TB GOLD was provided by the National TB
Controllers Association (NTCA) with the issue of their official position
statement (January 2005), advocating the use of FDA approved in vitro
diagnostic tests for diagnosis of latent TB infection. QuantiFERON-TB Gold is
currently the only such test. The NTCA states that "...the TST has many
limitations and that a new test to replace the TST has been sought for many
years." The NTCA recognizes that various problems with the TST, including
operational limitations, subjective interpretation, false positive and false
negative results "...make the TST a frustrating test for patients and
providers and have led to recommendations that are often poorly followed,
accepted, or understood." The NTCA believes that "...blood assays done in
vitro are likely to become the test of choice for most or all populations in