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New data question oseltamivir’s influenza efficacy, safety

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Convincing evidence of benefit lacking despite stockpiling

This publication of the most recent iteration of Cochrane reviews on the benefits and harms of oseltamivir and zanamivir marks the first time that reviews of these products included information from all the pertinent clinical trials conducted by the manufacturers. With these comprehensive new reviews based on all the data, the perspective on these drugs has changed substantially. With all the evidence available from treatment and prophylaxis studies it has become clear that convincing trial evidence of a reduction in the risk of hospitalization or complications is lacking.

In addition, the reviews found that oseltamivir causes nausea and vomiting, and probably causes heachaches, renal problems, and psychiatric syndromes. Zanamivir had fewer adverse effects but also had no demonstrated effect on complications or hospitalizations. Zanamivir reduced the duration of symptoms by about half a day, but the reviewers found that it may be no better than other symptom-relief medications. For prophylaxis, zanamivir significantly reduced the risk of symptomatic influenza, but there was heterogeneity among the studies and sample sizes were small. In addition there was no difference in asymptomatic influenza.

Based on these findings it is difficult to conceive that many patients would actively seek these treatments. The benefits involve a shortening of symptoms that few patients would find worth the risk of incurring the harms of treatment. From a health-system perspective, enormous expenditures on these drugs do not appear to have commensurate benefit.

Despite questions raised several years ago about full transparency on the risks and benefits of these two drugs, the medical establishment embraced them. Governments stockpiled the drugs, presuming that their potential public-health benefit merited a substantial financial investment. During this period, when not all of the trial results were fully and widely available, the Centers for Disease Control and Prevention, the U.K. National Institute for Health Care Excellence, the American Academy of Pediatrics, and the World Health Organization all suggested that oseltamivir and zanamivir provided benefits with minimal risks.

Of primary importance for decision makers is that now, with all of the data available for others to evaluate, the knowns and unknowns can be laid out clearly and reveal the weakness of the evidentiary support for these products and what we need to learn about them in the future.

Dr. Harlan M. Krumholz is a cardiologist and professor of medicine and director of the Center for Outcomes Research and Evaluation at Yale University, New Haven, Conn. He said that he has received research grants from Medtronic and Johnson & Johnson and that he chairs a scientific advisory board for UnitedHealthcare. He made these comments in an editorial (BMJ 2014;348:g2548 doi:10.1136/bmj.g2548).


 

FROM BMJ

"CDC welcomes the public release of all such data for academic review and discussion. These data have not changed CDC and ACIP’s recommendations for the clinical use of antivirals in the United States. Decisions regarding the purchase of antivirals for use in the U.S. Strategic National Stockpile in the event of an emergency are not made by CDC.

"It’s important to acknowledge that the neuraminidase inhibitor class of antiviral drugs, which includes Tamiflu and zanamivir, are a second line of defense against the flu. These drugs represent an important tool in the event of a flu outbreak, when a vaccine isn’t yet available. Such drugs are often the only treatment option available for flu, and while we all support the development of new and better drugs in the future, we must make the best use of the tools we have at our disposal to promote public health."

In June 2013, a multidisciplinary and international group of researchers developed an independent statistical plan for analyzing the full oseltamivir dataset with an eye toward determining the efficacy and safety of oseltamivir for treating and preventing influenza in both individual patients and for public health. The Multidisciplinary Group for Advice on Science (MUGAS) plans to present the results of its analysis in September at a meeting of the European Scientific Working Group on Influenza, according to Dr. Richard J. Whitely, professor and director of pediatric infectious diseases at the University of Alabama in Birmingham, and one of the organizers of the MUGAS project on oseltamivir.

Dr. Jefferson receives royalties from Blackwells and Il Pensiero Scientifico Editore, Rome, and gives interviews anonymously to market research companies about phase I or II pharmaceutical products. In 2011, he was an expert witness in a litigation case related to oseltamivir phosphate and in a labor case on influenza vaccines in health care workers in Canada. He has been a consultant for Roche, GlaxoSmithKline, and Sanofi-Synthelabo, and is currently a consultant for IMS Health.

BMJ support key

Dr. Jefferson called his 4-year effort to get full clinical-testing data on oseltamivir and zanamivir from the manufacturers a "campaign," and cited key support from the staff of the U.K.-based BMJ medical journal.

"If BMJ had not become involved neither Roche nor GlaxoSmithKline would have cooperated. BMJ pledged their support when we asked for the full clinical reports" in 2009, recalled Dr. Jefferson, who first raised the issue of getting wider data access and also led the Cochrane analysis on the new data.

The story began in 2009, during the H1N1 pandemic, which led to the Cochrane group’s receiving funding to perform an update to a neuraminidase-inhibitor review they had done in 2006. In the intervening years, information emerged suggesting a large cache of unpublished data had never been seen during the 2006 review, which focused on published materials.

"In 2011, we decided not to accept anything that had been published because it was biased," Dr. Jefferson said in an interview.

BMJ editors compiled details and links on this web page to the thrusts and parries between themselves and Cochrane staffers and the two companies involved, Roche and GlaxoSmithKline, during the several years it took to receive and evaluate the full data: www.bmj.com/tamiflu.

In an editorial accompanying the two reports from Cochrane on oseltamivir and zanamivir, Dr. Fiona Godlee, editor-in-chief at BMJ, Dr. Elizabeth Loder, another BMJ editor, and Dr. David Tovey, editor-in-chief of the Cochrane Library, called the Cochrane reviewers and their associates who authored the two papers "pioneers" for "navigating the uncharted territory" of the data analyses they performed using huge numbers of clinical study reports (BMJ 201;348:g2630 [doi: 10.1136/bmj.g2630]).

Dr. Loder, Dr. Tovey, and Dr. Godlee also said in their editorial that they saw the effort to get more data on the neuraminidase inhibitors as part of a larger effort to remake the way that drugs are assessed and reviewed.

The process required to obtain and analyze the neuraminidase inhibitor data showed "with greater clarity than ever that the current system is broken," they wrote. "The review’s conclusions should lead to serious soul-searching among policy makers. So, too, should the story behind the review, illustrating as it does the entrenched flaws in the current system. Why did no one else demand this level of scrutiny before spending such huge sums of money on one drug?" they asked.

Dr. Godlee said that she and BMJ have been closely involved from the outset in the campaign for access to clinical trial data on oseltamivir. She coedited a book on peer review with one of the Cochrane authors, Dr. Tom Jefferson. She and BMJ work closely with another of the Cochrane authors, Carl Heneghan, on jointly hosted conferences. She recently recruited a third Cochrane author, Peter Doshi, to the staff of BMJ as an associate editor. She was not directly involved in the decisions to accept the neuraminidase inhibitor papers for publication in BMJ but will undoubtedly have communicated to her editorial colleagues her keenness that BMJ should publish them if at all possible.

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