By Lacy Boggs
The
ball was equivalent to an approved product; the socket was
equivalent to an entirely different approved
product; and the materials were equivalent
to still a third approved product.
Since 1976,
all medical devices must be
classified and approved by the U.S. Food and Drug Administration
(FDA) before they can be legally
marketed to the public. It is the fond belief of
many Americans that FDA approval is a ringing endorsement of
a product's safety, a guarantee that
the device has been tested and re-tested by professionals who are
presumably trained to put the device
through all kinds of rigor to triple-check
its safety and effectiveness before allowing it anywhere near our
fragile human bodies.
It is, as we say, a fond belief, but
not an accurate one. It seems that many medical
devices - including the recently recalled DePuy ASR XL
Acetabular System - are given an FDA
approval and subsequently placed inside people's bodies without ever
going through a single test at the
FDA.
The FDA department responsible for
the regulation and review of medical devices
is the Center for Devices and Radiological Health (CDRH). CDRH
divides medical devices into three
classes: life-sustaining, life-supporting or implantable devices are
designated as Class III.
Hip replacements, including the ASR
XL system, qualify as a Class III device and
are considered high risk to the patient's health.
Class III devices can be approved by
the FDA through one of two processes. The first,
the premarket approval process
(PMA) is more or less what we think of when we
imagine our device being tested by the FDA: an extensive
review including rigorous clinical
trials that show it to be safe for use in humans. The PMA is quite
detailed, lengthy, and expensive,
usually costing the manufacturing company upwards of $250,000
and taking as much as two years to complete.
A quarter of a million is a large
chunk of change - but thankfully for companies
with a firm eye on their bottom line, there's always the
second FDA approval process.
The premarket notification approval process, also known as the 510(k) approval process,
is a sort of shortcut to approval that lowers the
price point considerably - and also, conveniently, doesn't
involve any pesky testing that might
reveal a flaw in the product that would then have to be revamped and
retested for another quarter-million.
The 510(k) process basically
pre-approves any product that is deemed "substantially
equivalent" to another product already legally
approved for sale. It costs less than
$5,000, requires no clinical trials, and only takes an average of 3-6
months to complete. It's a good
shortcut for products that are essentially identical to
their forebears. After all, it hardly makes sense to
waste the FDA's time when they could
be helping get new, innovative, life-saving products to market. But
what's to stop companies from
claiming their products are "substantially equivalent" to
other FDA-approved devices even if they're not
remotely the same?
What, indeed
The ASR XL Acetabular hip replacement system
got its seal of approval from the FDA using the 510(k)
process, claiming that its product was substantially
equivalent to other hip replacement
devices already on the market. The FDA official in charge of approving
the device would have gone through a
checklist that included the following questions (simplified;
the actual document is fairly dense):
- Does the new product treat or solve the same problems as previously approved products?
- Does the new product have the same design, materials, and energy sources as previously approved products?
- Could any new characteristics or combinations of characteristics affect safety or effectiveness?
The first question is easy: there
are dozens of hip replacement devices on the market,
all designed to help people walk even after their bum
hip throws them out of commission.
The second question gives us a bit of a hiccup: the ASR XL Acetabular
hip replacement system had two parts,
a ball and socket
The
ball was equivalent to an approved product; the socket was
equivalent to an entirely different approved
product; and the materials were equivalent
to still a third approved product.
Thankfully for DePuy, the FDA had
thoughtfully included a caveat that allowed for
such an eventuality. Which brings us to question three: could
any new characteristics affect
safety?
In DePuy's 501(k) application,
it declared that the "subject device does not raise any new
issues of safety or effectiveness." A brave
statement, though one wonders how the
company confirmed such a diagnosis without going through any clinical
trials. Perhaps if it had, the
problem of metallosis would have become evident before the hips were
implanted into approximately 93,000
people.
With such prerequisites for FDA
approval, it is perhaps not surprising that only 10% of 510(k)
applications are referred back for supporting human, clinical or animal
testing.
Which is to say that 90% of claims
require no clinical testing whatsoever before being sold to patients.
That's not to say that there is no testing at all. If a mechanical test is available,
510(k) approval process requires that the new product show that it
yields similar results to a previously approved product. The DuPuy ASR
hip replacement system took a few spins on a robot that went through
simulated movements. In a legal suit brought against DePuy for a
different hip implant last year, the mechanical test did not include the
full range of motion of which a human being is capable. Read more ....
