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Medical Devices – No Controlled Trials

Posted by Colin Rose on July 24, 2008

“I’m not allowed to prescribe one pill unless it has gone through years of trials,” said Dr. Colin Rose, a Montreal cardiologist. “Why can they license these [devices] — which can be just as dangerous — with no controlled trials? What is the difference?


MEDICAL IMPLANTS
BY TOM BLACKWELL
National Post
24 Jul 2008

Late in the 1990s, Health Canada licensed a new artificial lens, the latest in an innovative generation of implants for treating cataracts. Made from a foldable material, it could be inserted in the eye with a smaller incision than usual and less-invasive surgery. It did not matter, under the department’s rules, that the device had been tested on relatively few people before being approved.

As thousands of the newly licensed lenses were installed worldwide, however, doctors started noticing a serious defect with many of the implants: they were turning opaque inside patients, and in some cases had to be removed with a much more complex operation through the individual’s temple.

“ The ophthalmologists were petrified,” said Dr. Pierre Blais, a former Health Canada official who now does consulting work on medical devices for insurance companies. “They said, ‘We can’t trust these [regulatory] agencies. We have to do our own trials.’ ”

But the eye implant case was no exception. Health Canada routinely approves surgical devices after limited — or no — study on humans, far less evidence than is required for the certification of prescription drugs. And now some experts are raising serious concerns about the process.

The number of devices being inserted into Canadians’ bodies is soaring, and there is no doubt many work wonders: saving patients’ eyesight, relieving debilitating joint pain or preventing lethal heart irregularities.

In a recent article, however, several prominent obstetricians and gynecologists accuse Health Canada of failing in its ethical duty to protect patients, and call on the regulator to impose the same kind of strict approval criteria for devices as for drugs.

“Most people assume that … any surgical device licensed in Canada must be safe for human use,” notes the paper, co-authored by the president of the Society of Obstetricians and Gynaecologists of Canada. “As things currently stand, this assumption is not justified.” The paper, published in the society’s scientific journal, cites Health Canada’s approval in 2006 of a new surgical implant to combat female incontinence. At the time, the device had never been tested on a single person. Within a year, though, the freshly approved “vaginal tape” had been permanently installed in more than 1,000 Canadian women.

Individual case reports have so far been generally positive, but a clinical trial proving they are safe and effective has yet to take place. Concerns reach beyond gynecology. A trial published last year found that angioplasty — a widely hailed procedure that uses a tiny balloon to clear harmful plaque from clogged arteries — did no better than much cheaper, intensive drug treatment and exercise to treat stable heart patients. The device had been used for years on about 40,000 Canadians annually, most of them stable.

“I’m not allowed to prescribe one pill unless it has gone through years of trials,” said Dr. Colin Rose, a Montreal cardiologist. “Why can they license these [devices] — which can be just as dangerous — with no controlled trials? What is the difference?”

Other doctors and the industry, though, argue that requiring devices to be extensively studied before approval would be impractical and hamper important innovation. With changes and improvements constantly being introduced, devices have a much shorter shelf life than drugs, meaning companies could not recoup the tremendous investment needed to conduct pricey clinical trials, they say.

“It would be great to have a perfect system that makes sure we understand what the benefits and risks are of everything,” said Dr. David Urbach, a Toronto surgeon who has studied how new surgical techniques are adopted. “But if it took 10 or 15 years to bring a device to market, you’d never use any devices, because they’d be obsolete. We still use drugs, antibiotics, developed 50, 60 years ago. We don’t use devices from even 10 years ago.”

Paul Duschene, a Health Canada spokesman, said the department submits devices to a “robust” approval process, including demands for information showing they are safe and effective. But devices do not need to be vetted the same way drugs do because “the hazards and risks posed to the patient are much different with a medical device,” he said.

Health Canada divides devices into four classes, depending on how much risk they pose to patients. The higher the class, the more evidence is required of a product’s safety and efficacy. Those considered to be incremental modifications of earlier products require less proof.

Class three — which includes gynecological implants such as the vaginal tape, and artificial hip replacements — and class four, including pacemakers and other heart devices, are the most controversial. The vaginal tape was approved based on lab tests and studies on animals, said the paper by the gynecology group.

Another, similar tape approved with no human studies a few years earlier caused considerable problems, frequently eroding inside bodies and triggering infection, said Dr. Sue Ross, a University of Calgary scientist and one of the paper’s authors.

Similar problems occurred with a sling used to reconstruct the uterine cavity in women who had had hysterectomies. The device was meant to prevent collapse of the cavity, but the mesh straps at the core of it would often deteriorate after a couple of years, causing abscesses and other problems, Dr. Blais said. He said the foldable lens — one version of a concept that has generally proven successful — was likely implanted in about 1,000 Canadians, many of them in Alberta, before being recalled.

Then there were heart valves coated with silver, an innovation meant to avoid infection but not tested widely in patients before being licensed in about 1997. As the device was widely distributed, doctors discovered the silver coating sometimes impeded proper melding of the valve with natural tissue, leading to leaks that may have killed some patients, Dr. Blais said. They were later recalled and are now the subject of class-action lawsuits.

In contrast to devices, drugs are regulated in a separate system that requires them to be studied on hundreds of people in a series of clinical trials, which compare the new product against a control group of patients taking a placebo or other treatment.

But Dr. Martin McKneally, a retired surgeon and bio-ethicist at the University of Toronto, argues that clinical trials cannot be carried out for devices when they are first introduced, since the products’ impact differs depending on how it is used by individual doctors, and techniques are honed over time. He believes the key is to adequately inform patients that the implant or other device they are about to receive is novel and has been tested on only a handful of other people.

“You have to learn in patients and keep modifying as you go along,” Dr. McKneally said. “The fact we have such excellent devices is a credit … in part to the patients.”

Even Dr. Blais, once fired and later reinstated over his outspoken comments while at Health Canada, said it may be unrealistic to expect the government to demand extensive clinical trials be done on surgical devices, except those with the highest risk.

It would be more practical for the regulator to simply be up front about the limited vetting that devices undergo before being licensed, and let patients decide if they will accept the risk, he said.

As it stands, Health Canada’s approval of devices “is a licence to test out an idea on somebody else, if possible at government cost,” Dr. Blais said. “What is happening now is we are becoming a nation of uninformed and unremunerated laboratory rats.”

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