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Showing posts with label safety. Show all posts
Showing posts with label safety. Show all posts

Tuesday, May 6, 2014

Safe Use of Repetitive Transcranial Magnetic Stimulation in Patients With Implanted Vagus Nerve Stimulators.

Brain Stimul. 2014 Apr 12. pii: S1935-861X(14)00129-6. doi: 10.1016/j.brs.2014.04.001. [Epub ahead of print]

Safe Use of Repetitive Transcranial Magnetic Stimulation in Patients With Implanted Vagus Nerve Stimulators.

Philip NS1, Carpenter SL2, Carpenter LL3.

Author information
  • 1Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, RI, USA; Laboratory for Clinical and Translational Neuroscience, Butler Hospital, USA; Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, USA. Electronic address: Noah_Philip@Brown.edu.
  • 2Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, RI, USA.
  • 3Laboratory for Clinical and Translational Neuroscience, Butler Hospital, USA; Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, USA.
Abstract

Vagus nerve stimulation (VNS) and repetitive transcranial stimulation (rTMS) devices are FDA cleared for therapeutic use in treatment resistant depression. Since VNS systems have ferromagnetic components and large-scale safety testing has not been done, the implanted VNS device is considered a contraindication for rTMS therapy. This contraindication should not be considered absolute, as VNS components typically lie outside the electromagnetic field generated by an rTMS treatment coil. We solicited information from clinicians at several academic medical centers through an informal survey about their use of rTMS for depressed patients with implanted VNS systems, and reviewed relevant safety issues with one rTMS device manufacturer. rTMS clinical practices may use special consent procedures and take additional precautions to enhance safety in these situations. Specific recommendations are provided for minimizing risks (heating or movement of VNS components and unintended change in VNS stimulation parameters) when delivering rTMS to patients with implanted VNS systems.

Copyright © 2014 Elsevier Inc. All rights reserved.

KEYWORDS:

Repetitive transcranial magnetic stimulation, Safety, Treatment-resistant depression, Vagus nerve stimulation

PMID:
24794163
[PubMed - as supplied by publisher]
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http://www.ncbi.nlm.nih.gov/pubmed/24794163

Monday, July 1, 2013

Breaking the Seal on Drug Research

Breaking the Seal on Drug Research

Steve Ruark for The New York Times

Peter Doshi, in background, wants to give consumers “the full picture” on drug data. He shared an article with Kevin Fain in a Johns Hopkins cafe.

By KATIE THOMAS
Published: June 29, 2013
PETER DOSHI walked across the campus of Johns Hopkins University in a rumpled polo shirt and stonewashed jeans, a backpack slung over one shoulder. An unremarkable presence on a campus filled with backpack-toters, he is 32, and not sure where he’ll be working come August, when his postdoctoral fellowship ends. And yet, even without a medical degree, he is one of the most influential voices in medical research today.
Related

Cochrane Archive, Cardiff University Library, University Hospital Llandough

Archie Cochrane, an influential British epidemiologist.

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Julia Yellow

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Chris Warde-Jones for The New York Times

Tom Jefferson, an epidemiologist, worked with Dr. Doshi in reviewing research about Tamiflu’s effectiveness.

Dr. Doshi’s renown comes not from solving the puzzles of cancer or discovering the next blockbuster drug, but from pushing the world’s biggest pharmaceutical companies to open their records to outsiders in an effort to better understand the benefits and potential harms of the drugs that billions of people take every day. Together with a band of far-flung researchers and activists, he is trying to unearth data from clinical trials — complex studies that last for years and often involve thousands of patients across many countries — and make it public.

The current system, the activists say, is one in which the meager details of clinical trials published in medical journals, often by authors with financial ties to the companies whose drugs they are writing about, is insufficient to the point of being misleading.

There is an underdog feel to this fight, with postdocs and academics flinging stones at well-fortified corporations. But they are making headway. Last fall, after prodding by Dr. Doshi and others, the drug giant GlaxoSmithKline announced that it would share detailed data from all global clinical trials conducted since 2007, a pledge it later expanded to all products dating to 2000. Though that data has not yet been produced, it would amount to more than 1,000 clinical trials involving more than 90 drugs, a remarkable first for a major drug maker.

The European Medicines Agency, which oversees drug approvals for the European Union, is considering a policy to make trial data public whenever a drug is approved. And on June 17, the medical world saw how valuable such transparency could be, as outside researchers published a review of a spinal treatment from the device maker Medtronic. The review, which concluded that the treatment was no better than an older one, relied on detailed data the company provided to the researchers.

For years, researchers have talked about the problem of publication bias, or selectively publishing results of trials. Concern about such bias gathered force in the 1990s and early 2000s, when researchers documented how, time and again, positive results were published while negative ones were not. Taken together, studies have shown that results of only about half of clinical trials make their way into medical journals.

Problems with data about high-profile drugs have led to scandals over the past decade, like one involving contentions that the number of heart attacks was underreported in research about the painkiller Vioxx. Another involved accusations of misleading data about links between the antidepressant Paxil and the risk of suicide among teenagers.

To those who have followed this issue for years, the moves toward openness are unfolding with surprising speed.

“This problem has been very well documented for at least three decades now in medicine, with no substantive fix,” said Dr. Ben Goldacre, a British author and an ally of Dr. Doshi. “Things have changed almost unimaginably fast over the past six months.”

Much of that change is happening because of what Dr. Goldacre calls an “accident of history.” In 2009, Dr. Doshi and his colleagues set out to answer a simple question about the anti-flu drug Tamiflu: Does it work? Resolving that question has been far harder than they ever envisioned, and, four years later, there is still no definitive answer. But the quest to determine Tamiflu’s efficacy transformed Dr. Doshi and others into activists for transparency — and turned the tables on drug makers. Until recently, the idea that companies should routinely hand over detailed data about their clinical trials might have sounded far-fetched. Now, the onus is on the industry to explain why it shouldn’t.

IN summer 2009, Dr. Doshi received a call from Dr. Tom Jefferson, a British epidemiologist based in Rome. That year, the swine flu pandemic was spreading worldwide, and Dr. Jefferson had been hired by the British and Australian governments to update an earlier review of Tamiflu, a drug produced by the Swiss company Roche, aimed at reducing the flu’s severity and preventing more serious complications. He asked if Dr. Doshi wanted to help.

Determining Tamiflu’s efficacy had significant economic as well as health consequences. Around the world, private companies and governments — including that of the United States — were stockpiling Tamiflu in case of influenza outbreaks, and their spending accounted for almost 60 percent of the drug’s $3 billion in sales in 2009.

The review of Tamiflu was being conducted under the auspices of the Cochrane Collaboration, a well-regarded network of independent researchers, including Dr. Jefferson, who evaluate medical treatments’ effectiveness by analyzing all available research.

At the time, Dr. Doshi knew little about clinical trials or even much about the drug industry. But he knew Dr. Jefferson. Dr. Doshi, after receiving undergraduate and master’s degrees in anthropology and East Asian studies from Brown and Harvard, had shifted focus and was pursuing a doctorate at M.I.T., studying the intersection of medicine and politics. He met Dr. Jefferson, a prominent skeptic of the flu vaccine, after researching whether the Centers for Disease Control was exaggerating the deadliness of the disease.

“We were both lone wolves in the field of influenza,” Dr. Doshi recalled.

Dr. Jefferson had conducted a Cochrane review of Tamiflu’s effectiveness a few years earlier, concluding that the drug reduced the risk of complications from the flu. He assured Dr. Doshi and other researchers on his team that the update would be fairly simple.

But just as their work was getting under way, a simple comment arrived on the Cochrane Web site that changed the course of the research and would ultimately fuel a worldwide effort to force drug companies to be more transparent.

The author of that comment, Dr. Keiji Hayashi, had no connection to the Cochrane group; he was a pediatrician in Japan who had prescribed Tamiflu to children in his practice, but had come to question its efficacy. He was curious about one of the main studies on which Dr. Jefferson had relied in his previous analysis. Called the Kaiser study, it pooled the results of 10 clinical trials. But Dr. Hayashi noticed that the results of only two of those trials had been fully published in medical journals. Given that details of eight trials were unknown, how could the researchers be certain of their conclusion that Tamiflu reduced risk of complications from flu?

“We should appraise the eight trials rigidly,” Dr. Hayashi wrote.

Reviews by the Cochrane group are known for being among the most thoroughly researched medical analyses available. But in trying to answer the pediatrician’s question, Dr. Jefferson realized that there was a flaw: they relied too heavily on the assumption that the articles published in journals accurately represented the results of all clinical trials that had been conducted.

As he tried to track down the authors of the Kaiser study and the two published trials, Dr. Jefferson said he hit dead ends: One author said he had moved offices and no longer had the files; another said he had never seen the primary trial data, instead relying on a summary analysis provided by Roche. All the authors suggested that he contact the company.

“We took it on faith — on trust,” Dr. Jefferson, 59, said recently in a phone interview. Dr. Hayashi’s question had tested that faith. Dr. Jefferson began typing each new discovery in a private journal he called Hayashi’s Problem, which, he said, “charted my transformation from Dr. Jekyll to Mr. Hyde.”

Dr. Doshi said that medicine “relies on hierarchies of trust.” He added: “A patient is not going to be in a position to review the entire evidence base themselves. But they trust that there is a watchdog out there.”

As they dug into the Tamiflu research, Dr. Doshi said, he realized that such a watchdog didn’t exist. Instead, he said, “we have partial watchdogs who see part of the full picture.” It became his mission to see the full picture.

Having struck out with the authors of the disputed Kaiser paper and the two other published trials, Dr. Jefferson approached Roche itself, asking for the underlying data from the missing trials. But when he declined to sign a confidentiality agreement, Roche decided not to cooperate with the researchers.

Without more complete data about the clinical trials, the Cochrane group decided that it could not include the disputed study that summarized those results. In December 2009, the team reported that Tamiflu could not be shown to reduce complications like pneumonia or hospitalizations.

The British Medical Journal, which printed the team’s conclusions, also published its own investigation, showing that Roche had hired ghost writers to author some of the articles involving Tamiflu, and that those writers had said they were under pressure to highlight positive messages about the drug. Roche responded that hiring such writers was common industry practice at the time of the articles, and it rejected the idea that they had been pressured to write positively about the drug.

The articles in the British journal created a sensation, and the Cochrane Collaboration’s efforts became a cause célèbre. “Everyone knows about publication bias,” said Dr. Steven Woloshin, a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice and an advocate of more widespread sharing of clinical trial data. “But they just had so much energy and they brought so much attention to it.”

The group’s efforts seemed to make a difference: After the articles in the British journal, Roche turned over partial copies of study reports, amounting to a little more than 3,000 pages. Then, in 2011, the European Medicines Agency turned over more than 22,000 pages of documents for 19 trial reports to Dr. Jefferson and his team.

The door had been opened. As they read through the records, the researchers discovered the importance of documents called clinical study reports, which are thousands of pages long and contain details as varied as descriptions of trial protocol and design and the ingredients of the placebo pills.

“We used to know that there was a published paper and there were data behind it,” said Dr. Fiona Godlee, the editor of the British Medical Journal. “But people haven’t talked about these things, like clinical study reports, that are now being talked about a great deal.” Last fall, the journal said it would publish the results of clinical trials only if drug companies and researchers agreed to provide data upon request.

In April, Roche said it would make available to the Cochrane researchers clinical study reports for all Roche-sponsored trials of Tamiflu. Dr. Jefferson, Dr. Doshi and their colleagues hope to complete another update to their review of the drug by year-end.

Some said it was a shame that it took this long for the company to relent. “All these years later, and we still don’t know if Tamiflu is effective,” said Dr. Harlan Krumholz, the Yale cardiologist who oversaw the review of Medtronic’s bone treatment. “It’s perplexing to have a billion-dollar drug, and you’re still not willing to share everything you’ve got to know whether this thing is effective and safe.”

THOUGH the Tamiflu question is not yet resolved, the Cochrane researchers have succeeded in a bigger way: by helping to change the conversation around companies’ responsibility to reveal drug trial data.

Drug companies do not always credit the Cochrane Collaboration. In February, Roche followed Glaxo’s lead and announced that it, too, would release detailed clinical data to outside researchers, upon request. But Daniel O’Day, chief operating officer of pharmaceuticals at Roche, denied that its pledge had been motivated by the Tamiflu experience. He said Roche has provided data to “thousands” of researchers.

Mr. O’Day said “there were probably errors on both sides” in how the Cochrane researchers and Roche communicated with each other, and said the relationship deteriorated after Dr. Jefferson refused to sign a confidentiality agreement. He said the company was trying to rebuild its relationship with the Cochrane researchers, but that it stood by the safety and efficacy of Tamiflu.

In 2010, Roche commissioned researchers at the Harvard School of Public Health to conduct a re-analysis of Tamiflu clinical data, which largely confirmed the positive conclusions of the Kaiser study.

Mr. O’Day asserted that the company’s transparency pledge had arisen from “the call from society in general for greater transparency of the clinical trials that we have.” But others say the Cochrane researchers are largely responsible for that call for transparency.

Andrew Witty, Glaxo’s C.E.O., said in an interview that his promise to provide detailed clinical data had grown out of a companywide effort, initiated soon after he became chief in 2008, that would “really ensure that we were more in step with where I thought, frankly, society and the world was moving.”

Glaxo, moreover, was in need of an image rehabilitation. Last year, it pleaded guilty to criminal charges and agreed to pay $3 billion in fines after the United States Justice Department accused the company, based in London, of failing to report safety data about its diabetes drug Avandia, and of publishing misleading information about Paxil, the antidepressant, in a medical journal. The settlement, which also included civil penalties over marketing of other drugs, was the largest ever involving a pharmaceutical company.

“We don’t see any reason for this information to be held out of the public domain,” Mr. Witty said, “provided that the people who are interrogating the information are legitimate researchers with a legitimate question to ask.”

In a twist, Roche now finds itself on the same side as the Cochrane researchers — and against many in its own industry — in a debate over what kind of data the European Medicines Agency should be making public. On Monday, the agency released a draft policy, expected to take effect next year, in which it would release clinical trial data whenever it approved a new drug. While Roche and Glaxo have supported the policy, the Pharmaceutical Research and Manufacturers of America, a major industry group, and other drug companies have opposed it.

John J. Castellani, chief executive of PhRMA, said the industry had championed open-source efforts to develop better methods for testing cancer drugs, for example. But proposals like those from the Cochrane team and the European agency go too far, he said.

“If you dump onto the sidewalk all the data and you include commercially protected information,” he said, “then you’re essentially giving to competitors what we invested billions of dollars in.”

Others warned that such a policy could discourage drug companies from investing in Europe. “If you, on the other hand, say, ‘You guys are bad actors, we want to cut your prices, we want to take your confidential data and share it with any one of your competitors,’ you don’t get the same feeling of encouragement,” Christopher A. Viehbacher, C.E.O. of the French pharmaceutical company Sanofi, told reporters in Brussels on Monday, according to Reuters.

Industry officials and regulators in the United States say the public already has access to vast amounts of information about clinical trials. The basic results of all clinical trials must now be registered in a federal clearinghouse, for example, and the Food and Drug Administration publishes staff reviews and other documents when it approves a new drug. The F.D.A. has said that it is monitoring the developments in Europe but that federal laws in the United States restrict what types of information can be released, particularly data that could reveal personal or commercially confidential information.

Cochrane group members point to the Medtronic study as an example of the value of a neutral perspective.

In 2011, Medtronic awarded a $2.5 million grant to Yale and asked it to oversee a detailed review of trial data for Infuse, a bioengineered material in spinal fusions to treat back pain. The company was facing claims that it had published misleading information about the treatment, and it turned over its data in an effort to address those criticisms. Two teams that examined the data came to similar conclusions: Infuse appeared to be no better than an older treatment, and may pose added risks.

EARLIER this month, Dr. Doshi opened what he hopes will be a new chapter in his quest for greater understanding of clinical trials. He and several other researchers published what amounted to an ultimatum to drug companies: publish your data, or we’ll do it for you.

Under the plan, researchers would publish articles summarizing trial results in cases where the underlying data has already been released. In isolated cases, such information has been made public through litigation and Freedom of Information Act requests.

“It’s really neat to see a larger opportunity for a larger impact,” he said. “Tamiflu just happened to be the lever that opened that door.”

http://www.nytimes.com/2013/06/30/business/breaking-the-seal-on-drug-research.html?pagewanted=all&_r=0

Friday, October 28, 2011

Vagus nerve stimulation for epilepsy: the notre-dame hospital experience.

Can J Neurol Sci. 2011 Nov;38(6):902-8.

Vagus nerve stimulation for epilepsy: the notre-dame hospital experience.

Source

Division of Neurology, Montreal University Hospital Centre, Montreal, Quebec, Canada.

Abstract

Purpose: Retrospective study assessing the efficacy and tolerability of vagus nerve stimulation (VNS) for the treatment of refractory epilepsy at Notre-Dame Hospital. Methodology: Chart review of all adult epileptic patients treated by VNS with ≥ 1 year follow-up. Responders were defined as patients with ≥ 50% reduction of baseline seizure frequency. Results: Thirty-four patients (14M; mean age = 29.9 yrs) received a VNS. Sub-pectoralis implantation (n = 25) was more frequent than subcutaneous (n = 9). Most patients suffered from intractable partial epilepsy. After 6 months, 12 months, 24 months, and 36 months, 14/34 patients (41%), 16/34 patients (47%), 17/30 patients (57%) and 12/20 patients (60%) respectively were responders. Two patients (6%) became seizure-free. Complications related to implantation were minor: eight cases of limited cervical hypoesthesia, two minor scar infections and one Horner syndrome. Adverse events (voice hoarseness, throat paresthesia, coughing) related to stimulation were generally mild and tended to wane over time. However, a reduction in seizure frequency did not translate into a reduction in medication, as only 9% of responders had less antiepileptic medication at last follow-up compared to baseline. Conclusion: VNS as practiced at Notre-Dame hospital is an efficacious and safe treatment for refractory epilepsy. Quotas allotted to epilepsy centers in the province of Quebec should be lifted or increased to allow more patients to benefit from this therapeutic device.

PMID:
22030430
[PubMed - in process]
http://www.ncbi.nlm.nih.gov/pubmed/22030430

Saturday, November 6, 2010

Why the FDA can’t protect the public

BMJ 2010; 341:c4753 doi: 10.1136/bmj.c4753 (Published 2 November
2010)
Cite this as: BMJ 2010; 341:c4753
 
Why the FDA can’t protect the public
1.      Jeanne Lenzer, medical investigative journalist1,
2.      Shannon Brownlee, instructor, Dartmouth Institute for
Health Policy and Clinical Practice
2
+ Author Affiliations
1.      1New York
2.      2Washington,
DC
Medical
device makers often fail to properly conduct safety studies and the US Food and
Drug Administration provides scant oversight. Jeanne Lenzer and Shannon Brownlee look
at some of the problems with post approval surveillance of novel devices
In 1997, the US Food and Drug
Administration’s neurological devices panel met to consider approval of a vagus
nerve stimulator (VNS). The manufacturer, Cyberonics, said it could prevent or
reduce seizures in patients with partial onset epilepsy who did not respond to
drug treatment. The device consists of a generator the size of a matchbox that
is implanted under the skin below the patient’s clavicle. Lead wires from the
generator are tunnelled up to the patient’s neck and wrapped around the left
vagus nerve at the carotid sheath, where it delivers electrical impulses to the
nerve lasting about 30 seconds every 3-5 minutes.
Getting
approval
Representatives from Cyberonics offered no
definitive explanation during the FDA meeting of how the device stopped or
reduced seizures, but they had three studies, E03, E04, and E05, to show its
safety and efficacy.
Two of the
studies, E03 and E05, involved 313 patients with treatment resistant partial
seizures randomised to high or low dose stimulation. The low stimulation arm
was intended to avoid the problem of an unblinded placebo arm because all
patients would be implanted and told they were receiving stimulation. The
studies did not include a medical treatment arm for comparison, leaving
unanswered the question of whether either treatment arm was superior to
existing care.
Researchers
reported that 25% of patients in the high stimulation arms of the trials
achieved the primary end point: a 50% reduction in seizure frequency from baseline.
However, 20% of patients in the high stimulation arm had more seizures.1
Concerns
about safety
The safety of the device hinged on the
cause of death among 17 patients of the 1000 implanted with the device
worldwide. The device had been approved in Europe and Australia before approval
in the US. The most common cause of death among young epileptics is sudden
unexpected death from epilepsy (SUDEP), a poorly understood complication that
is thought to be related to cardiac or respiratory arrest that sometimes occurs
shortly after a seizure. SUDEP is reported most often among younger patients
and those with poorly controlled seizures.
2 3 The company told FDA panellists that
the deaths were from SUDEP or other causes unrelated to its product.
1 However, one panellist, Steven
Piantadosi, professor of oncology and biostatistics and a clinical trial
methodologist at Johns Hopkins, expressed concerns, saying, “I’m still a little
worried about the death rates that we are seeing.”
In the
data provided by Cyberonics, patients implanted with the device had a SUDEP
rate of 7.3/1000. Dr Piantadosi asked, “Should we be concerned by that?”
In
response to Dr Piantadosi’s questions, Ann Costello, an FDA reviewer, cited one
epidemiological study that showed an even higher SUDEP rate, 9.3/1000, among
treatment resistant patients about to have brain surgery to treat their severe
seizures.4 W Allen
Hauser, a member of Cyberonics’ scientific advisory board, also responded to Dr
Piantadosi’s concerns, saying, “I don’t think that the sudden death is an issue
specific to the device. It’s a specific issue in terms of people with bad
epilepsy.”
Conditions
of approval
Dr Piantadosi continued to express concern
about the SUDEP rate, but the advisory panel nonetheless voted unanimously to
approve the vagus nerve stimulator for patients with treatment resistant
partial seizures. The FDA made the approval conditional: Cyberonics would have
to conduct a post-approval study to examine the safety of the device and it
would have to report promptly all serious adverse reactions to the agency.
5
In
the 13 years since the device was approved in the US, more than 900 deaths have
been reported to the FDA, and it is still not clear what impact, if any, the
device has had on patient mortality. Although Cyberonics conducted
post-approval studies, none of the studies submitted to the FDA included
mortality data. The FDA did not specifically require Cyberonics to submit
mortality data as part of the follow up study, merely to “characterize
morbidity and mortality.” According to a spokesman for Cyberonics, the company
did collect mortality data from the Social Security Death Index, but they have
not published the results and they declined to show the data to the BMJ. The FDA told the BMJ that it has not
requested further studies concerning mortality.
Problems
with post-approval surveillance
The FDA’s failure to request and rigorously
monitor mortality data related to the VNS is but one example of the gap in
post-approval surveillance of medical devices. Most devices and drugs on the
market are supported by studies that are underpowered to detect rare but
potentially life threatening events that can kill tens of thousands of people
if the drug or device is widely used.
6 The impracticality of conducting
large scale clinical trials before approval for every drug and device places a
burden on post-approval surveillance.
This
burden is especially important for devices because they are less likely than
drugs to be supported by clinical studies before use. Less than one third of
devices approved under FDA’s premarket approval process had been evaluated in a
randomised study, according to a review of 78 high risk cardiovascular devices
approved by the FDA from 2000 to 2007.7 Just 5% were supported by two or
more blinded, randomised studies. Most of the outcomes measured, according to
the FDA study, were surrogate markers.
To
monitor safety of devices, the FDA relies on reports of harms associated with
devices once they have been approved. According to the agency, the most
“comprehensive source of information about the safety and effectiveness” of
devices as they are used in everyday circumstances is its Manufacturer and User
Facility Device Experience (MAUDE) database.8 However, the data contained in the
database does not constitute a comprehensive record of the numbers of adverse
events or exposures, and thus can only pick up “signals” of possible safety
problems that could be used to trigger more definitive investigation (box). Of
course, these signals can be picked up only if someone is monitoring the data.
An FDA taskforce on device regulation concluded in August, however, that
“challenges” in “current data sources . . . make it difficult to . . .
effectively obtain complete information about the risks and benefits of
regulated products.”9
The problem with MAUDE
Although
reports of adverse events associated with medical devices doubled from 2003 to
2007,
8 the MAUDE
database remains an imperfect tool.
6 10 Several factors can contribute to
under-reporting, including the voluntary nature of the reports; fear of
litigation by surgeons and others in a position to report the event; and
failure by patients and healthcare providers to connect new medical problems
with a device.
11 Even
when device related adverse events do make it into FDA’s databases, 39% are
reported late.
8 A review
by the BMJ of
deaths among vagus nerve stimulator patients listed in the FDA’s database shows
that some deaths weren’t reported until several years after the patient died.
Perhaps the most serious flaw in the MAUDE database is
the fact that manufacturers—not the FDA or any other independent body—can decide
whether the device is connected with a negative outcome. Manufacturers are not
required to report deaths or serious adverse events if they decide that the
events were unrelated to the device.12
The
FDA’s ability to detect potentially unsafe devices is further hampered by the
fact that many post-approval studies required as a condition of the device’s
approval are not conducted or conducted so poorly as to be meaningless. In
2005, the FDA evaluated the quality of post-approval studies. Susan Gardner,
director of the Office of Surveillance and Biometrics at the Centers for Device
and Radiological Health, which oversees approval and safety of devices, told an
FDA advisory panel that 45 of the 127 premarket approvals granted between 1998
and 2000 had orders requiring post-approval surveillance or studies. But more
than one fifth of the studies, she said, couldn’t be evaluated for quality
because there was no record at the FDA showing they had ever even been
conducted.13 FDA has
since automated its records but many companies continue to submit data deemed
“inadequate” by the agency, while other studies remain unreported.
Warning
signs
So what does the MAUDE database tell us
about the vagus nerve stimulator? Most MAUDE death reports, which are mainly
written by manufacturers, contain descriptions so brief that no definitive
cause of death can be inferred. Despite the paucity of information available
(narratives are often just a sentence or two in length), the device is often
exonerated. For example, one death associated with the VNS was reported to be
from SUDEP on the basis of a “visual autopsy.” Marcia Angell, a pathologist and
former editor in chief of the New
England Journal of Medicine,
says that without an actual autopsy it
is impossible to determine whether it was SUDEP or some other factor, including
potentially the device itself, that caused the patient’s death, and even then
causality could remain uncertain.
Some
narrative descriptions, however, are clear enough that further investigation of
the device would seem warranted. For example, on 4 December 2008, a patient
with a vagus nerve stimulator was admitted to hospital after an abrupt increase
in seizures and was found to have “severe asystolia” coincident with vagus
nerve stimulation. The device was disabled and the asystole ceased. The
database has more than a dozen reports in which the device’s activity seems to
be associated with asystole.
The
database also contains reports of what could conceivably be downstream effects
of asystole and bradycardia, such as increased “seizures,” new onset drop
attacks, and fainting—which in turn could be responsible for some instances in
which patients were reported to have died in a fall, by drowning, or in a road
crash.
Another
case that ostensibly should have prompted further investigation by the FDA, was
that of 48 year old Dennis Fegan. According to medical records obtained by the BMJ with Mr Fegan’s
permission, he woke up in pain at 2 am on 2 July 2006, only to pass out. After
regaining consciousness, Mr Fegan, who had a 14 year history of partial complex
seizures, passed out several more times. He thought he was having an unusually bad
run of seizures. When an ambulance crew arrived, they witnessed Fegan having a
seizure and administered intravenous diazepam. Once he was at the hospital and
connected to a cardiac monitor, an apparent cause of his seizures emerged; at 3
minute intervals, his heart stopped for 30 seconds—synchronous with the firing
of his vagus nerve stimulator. As soon as the device was disabled, the asystole
ceased. His neurologist, a consulting cardiologist, and the treating emergency
physician concluded that the device was the likely cause of his asystole.
Denominators,
study bias, and failure to report
The FDA cautions that the MAUDE database
“is not intended to be used either to evaluate rates of adverse events or to
compare adverse event occurrence rates across devices.”
14 Its purpose is to allow FDA
analysts and others to pick up “signals” of harm that can trigger further
investigation. Any investigation would need to evaluate the numerator (number
of adverse events) and the denominator (number of exposures), but this
information is routinely absent.
In
the case of the vagus nerve stimulator the denominator depends not only on the
number of patients implanted with the device but also on how many devices are
still functioning. Cyberonics reports that by 10 March 2010, they had received
registrations for 57 284 patients worldwide implanted with the device, yet it
acknowledges that it is impossible to know how many patients have had their
devices deactivated because it has no way to collect these data. The
combination of possible under-reporting of adverse events (the numerator) and
possible over-reporting of the number of active devices (the denominator) could
mean that the rate of deaths among device users is higher than is apparent. The
more than 900 deaths among relatively young people (most of those with implants
are 15 to 44 years old) 3 did not trigger a request for
further investigation.
And
what of the post-approval study, known as XE05, ordered by the FDA as a
condition of approval? A spokeswoman for the FDA cited XE05 as part of the
evidence that “supported the long term safety and effectiveness of the device.”
Cyberonics confirmed that only 50 patients were enrolled in the open label
study and deaths were not recorded. When asked how such a small study that
didn’t include mortality data could show the device’s “long term safety,”
Cyberonics replied that “the purpose of that study wasn’t to look at SUDEP or
mortality rates” but to evaluate other long term safety issues.
The
FDA gave the BMJ
references to five additional post-approval studies as evidence of the device’s
safety. Yet the five studies do not establish that the device wasn’t responsible
for deaths because none of them included mortality data. The largest study
consisted of 4743 patients in the company’s outcome registry. The other studies
evaluated subsets of registry patients. Cyberonics acknowledged that “mortality
was not an endpoint collected as part of the Epilepsy Patient Outcomes
Registry.”15
In
2005, the FDA approved the vagus nerve stimulator for the treatment of
depression, despite the unanimous recommendation against approval by its own
scientists. The FDA experts were concerned, in part, about the device’s safety.
Nicholas Stine, who was then a research associate at Public Citizen, a public
interest group, wrote to the agency, urging that the device should not be
approved for treating depression. He and his coauthor, Peter Lurie, now adviser
to FDA’s assistant commissioner for policy, said that “numerous reports” of
worsening depression, suicides, and sudden deaths during clinical trials of vagus
nerve stimulation “had not been adequately investigated,” and that the
manufacturer “had not demonstrated long term safety of the device.”16 However, Cyberonics told the BMJ: “The FDA concluded
that Cyberonics provided ‘reasonable assurance of safety and effectiveness’ of
VNS therapy for the treatment of depression based on valid scientific evidence.
There is no evidence linking VNS therapy to worsening depression, suicides, or
sudden deaths.”
The
company has also suggested that the stimulator might have a role in treating
obesity, stroke, traumatic brain injury, and other conditions, and has
previously taken out patents for these potential therapies.17
Potential
solutions
The gaps in post-approval monitoring of the
vagus nerve stimulator are emblematic of the FDA’s surveillance of all devices.
Many of the problems have relatively easy fixes. Although the MAUDE database is
flawed, it can still serve its purpose if qualitative signals are detected and
trigger better analysis and quantification of a potential safety issue.
Manufacturers could be required to regularly submit denominator data, which
could be facilitated by requiring companies to provide a website link that
patients or their surgeons could use to report whether the device is disabled
or removed. An independent review panel could be appointed to decide whether
adverse outcomes could be excluded from reporting. And, as the FDA has
suggested, mechanisms to limit widespread uptake of new devices could be put in
place so that fewer patients are harmed if it ultimately turns out that newly
approved devices are flawed.
Notes
Cite this as: BMJ 2010;341:c4753
Footnotes
·       Competing interests:
JL and SB have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf
(available on request from JL and declare: no support from any organisation for
the submitted work; no financial relationships with any organisations that
might have an interest in the submitted work in the previous three years; no
other relationships or activities that could appear to have influenced the
submitted work.
·       Provenance and peer
review: Commissioned and peer reviewed.
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