|
By Ken Bahk
10/09/07
What Is Driving Molecular Point-of-Care Testing? A Perspective on Clinical
and Market Forces
Molecular diagnostics provides clinically imperative information that is not
currently offered to all patients. The question is how to provide this clinical
knowledge to as many appropriate patients as possible while enabling the health
care system to conduct the testing. This article illustrates the forces involved
in the diagnostic continuum from biomarkers to point of care (POC), and discusses
why it is not available to all patients and what would be required to bring
molecular diagnostics to a wider population.
The Diagnostic Continuum
“A study conducted by Burrill & Company determined that literally
hundreds, if not thousands, of new biomarkers are found each year,” says
Kenneth Bahk, PhD, Director of Marketing for Nanosphere, Inc. (Northbrook,
IL). “These biomarkers are unearthed in research labs, and after significant
validation move through to the esoteric, commercial, and university teaching
hospitals where they are employed. After some time and additional application,
they are allowed to move through to the community hospitals, and ambulatory
care facilities—and perhaps eventually even to the home, field, and self-test
arenas.”
As the following chart illustrates, as you move outward from the lab there
are additional applications in terms of the number of places where the tests
are used. 
“This applies not only to new biomarkers, but also to new technology
and, specifically, molecular diagnostics. Along this continuum we have two
dynamics in play—a push and a pull,” he elaborates.
“We have a push of medical advances and clinical demand in the
direction toward the point of care,” Bahk continues. “Conversely,
you have a pull constraining this type of technology either by the perceived
or realistic issues of complexity, cost, specialized labor, and facilities.
At the end of the day, the result is that you are at two extremes.”
At
one end is esoteric testing, characterized by batch processing, long turnaround
times, specialized labor and equipment, and the need for analysis and interpretation
of results. At the other extreme, as an example, you have a simple handheld
blood glucose meter—a fully decentralized adoption of testing conducted
in individual homes. “However, keep in mind that these decentralized
diagnostics really do need to be highly reliable, specific, accurate, enable
random access unit use, have low-cost universal platforms, provide sample-to-result
operation, offer operator independence, and require no data interpretation,” Bahk
elaborates. “The last three items serve to reduce user error associated
with the potential to perform the test incorrectly.”
In effect, there
are a number of junctures along this continuum. “To
move from the labs through to teaching hospitals, one moves through a process
of biomarker validation,” he explains. “Moving from this point
to community hospitals requires enabling technology that allows that functionality
and sophisticated knowledge. While moving further along these nodes also requires
enabling technology, when you get to the far end (i.e., ambulatory care), one
really needs to provide evidence that there is medical value specifically at
this location.”
Finally, when you move to the field of self-testing, enabling
technology is a consideration, but also you have an interesting dichotomy of
safety versus medical necessity, Bahk relates. “It is true that in many
cases, including glucose and cardiac testing, that POC testing does indeed
improve the quality of care for these patients. However, at the same time,
we have to ensure that these tests can actually be performed and that the data
acquired can be applied in an appropriate manner that improves patient care.”
Clinical
and Market Forces
The College of American Pathologists defines POC
testing as, “analytical
testing performed outside a central laboratory, using devices easily transported
to the patient.” Bahk adds that this also implies near-patient testing,
alternative-site testing, and satellite testing (i.e., ER departments).
There
are forces that allow and shape a new technology as it moves through the continuum—glucose
monitoring and cardiac technologies exemplify how POC testing has progressed.
“In terms of glucose testing, the clinical
value is the ability to manage diabetes,” says Bahk. The first enabling
technology was the Folin-Wu method, based on Benedict’s Principal, and
it enabled the use of whole blood instead of plasma and serum. Next came automated
chemistry technologies, followed by urine strip tests that provided added functionality
and decreased the threshold necessary to perform the test. Finally, we have
self-monitoring of blood glucose (SMBGs).
“In terms of how enabling technologies
have affected medical value, necessity, and safety, the tests were in their
early stages performed in a hospital and self-testing was enabled,” Bahk
explains. “However, at this point,
the patient is not allowed to adjust specific insulin doses. Fast-forward to
the SMBG, which can be used to adjust insulin levels in real-time. Rapid diagnostic
information and the application of that information resulted in improved patient
care.”
The key is that this test, as well cardiac markers and technologies,
are time-critical. “The
tests that will probably be the first to move molecular diagnostics to the
point of care will be time-critical in nature,” Bahk says.
“The
second example of POC testing refers to cardiac technologies, beginning with
electrophoresis and followed by ELISA, which added functionality with improved
efficiency,” he continues. “That was followed by electrode
and microelectrode technology, which enabled functionality and information
at the POC. With a microelectrode, you can perform the test at bedside (i.e.,
in an ER) and the diagnostic information can be rapidly acquired and applied
to change treatment. Again, this mirrors the idea of the time-critical nature
of tests.”
 The example of cardiac technologies also offers another insight—POC
testing must fulfill all market needs. The chart at right illustrates two actual
companies and their products broken down by characteristics, cost, instrument
placements, and annual approximate disposables.
“Potentially, these two
companies realized that the forces, which push along the use of biomarkers
and acceptance of new technologies along this continuum, need to be combined
and embodied within their products,” Bahk says.
“At the end of the
day, Firm B did a better job capturing and understanding the needs of the market.
Likewise, those of us in the academic, industry, and clinical areas of molecular
diagnostics need to determine what is the best clinical and diagnostic solution
that fits under the auspices and constraints of the healthcare system, and,
in the end, will reach the patient.”
In summary, the clinical and market
forces that will drive POC testing include medical necessity, enabling technologies
that move along the continuum (from labs to self-testing). “To allow
tests to be done in certain environments, we also need to ensure that they
can be performed appropriately, that data can be interpreted properly, and
that the results can be applied to improve patient care,” Bahk notes.
However,
the time-sensitive nature of tests will be the driving force behind POC molecular
tests only if market needs are fulfilled. “This implies
that the test is easy to use and cost-efficient,” he adds.
POC Driven
by Urgency and Practicality
The forces that may drive POC molecular testing can be characterized under
two different categories—urgency and practicality, Bahk believes.
“As I stated earlier, tests that are time-critical will be first—i.e.,
tests where the results are critical to initiate treatment, for example, in
the case of Group-B strep, bioterrorism agents, Methicillin-resistant Staphylococcus
aureus, and intraoperative applications (in terms of identifying whether an
individual has cancer).
On the other side, you have practicality. “These
are tests that are appropriate to be done in a short time frame. At an STD
clinic, for example, this might be the only time you see these patients and
you want to ensure that this diagnostic information is provided. When it comes
to pharmacogenomics, I’d much
rather get my script and meds today as opposed to having to wait three days,” Bahk
concludes.
|
