'Hidden' trial data reveals that some Tamiflu claims were unfounded, researchers say
THURSDAY, April 10, 2014 (HealthDay News) -- No evidence exists to show that anti-flu medicines stockpiled by countries around the world protect people from the spread of flu or reduce related hospitalizations and complications, a new analysis contends.
The report from the nonprofit Cochrane Collaboration urges world leaders who spend countless dollars on medications like Tamiflu and Relenza for use in an influenza pandemic to reconsider this practice.
The findings, published April 10 in the BMJ, come from an analysis of internal reports of 20 Tamiflu (oseltamivir) and 26 Relenza (zanamivir) trials that involved more than 24,000 people.
Taking one of these drugs may reduce flu symptoms in adults by less than a day compared to taking an inactive placebo, the researchers found. However, they said claims that the drugs -- known as neuraminidase inhibitors -- curb flu transmission or reduce complications such as pneumonia are unfounded.
"We now have the most robust, comprehensive review on neuraminidase inhibitors that exists," said Dr. David Tovey, Cochrane editor-in-chief, in a news release from the research network.
"Initially thought to reduce hospitalizations and serious complications from influenza, the review highlights that Tamiflu is not proven to do this, and it also seems to lead to harmful effects that were not fully reported in the original publications," Tovey added.
Those side effects include headache, nausea and vomiting, the new study said. Some trials also noted an increased risk of psychiatric disturbances and kidney problems.
Evidence from the trials and studies reviewed showed that Tamiflu and Relenza alleviated flu-like symptoms in adults about half a day faster than in those taking a placebo. But the researchers found no proof that Tamiflu stopped someone infected with flu from transmitting it to others or that it prevented hospitalizations.
Nor was there evidence that the drugs lessened the odds of developing flu-related pneumonia, sinus problems or middle-ear infections in adults, researchers said.
Use of Tamiflu soared worldwide after the H1N1 "swine flu" pandemic of 2009, and governments began stockpiling the antivirals at great cost hoping to prevent widespread illness or deaths. The World Health Organization considers it an "essential" medication.
The United States has spent more than $1.3 billion building a reserve supply of antivirals, according to published reports.
"We need better antivirals, including combination antiviral treatments, but right now this is all we have got," said Dr. Tim Uyeki of the U.S. Centers for Disease Control and Prevention's flu division, according to an NBC News report.
"CDC recommends early antiviral treatment as soon as possible for any hospitalized patient with suspected or confirmed influenza," he added. "The number of observational studies suggesting the benefit of early antiviral treatment in hospitalized patients keeps growing."
Concerned about the safety and effectiveness of flu antivirals, Cochrane fought to get more information on the trials and studies behind these drugs. The new study is based on reports from Tamiflu maker Roche; GlaxoSmithKline, which makes Relenza; and the European Medicines Agency, the drug regulatory agency for the European Union.
In a statement reported by the Economic Voice, Roche said it "fundamentally disagrees" with the Cochrane report's conclusions. "We firmly stand by the quality and integrity of our data, reflected in decisions reached by 100 medicines regulators across the world and subsequent real-world evidence demonstrating that Tamiflu is an effective medicine in the treatment and prevention of influenza," the statement said.
Cochrane's Tovey said the recent information "shows the importance of ensuring that trial data are transparent and accessible."
Dr. Fiona Godlee, editor-in-chief of the BMJ, went further.
"This review is the result of many years of struggles to access and use trial data, which was previously unpublished and even hidden from view. It highlights with certainty that future decisions to purchase and use drugs, particularly when on a mass scale, must be based on a complete picture of the evidence, both published and unpublished," Godlee said in the news release. "We need the full data from clinical trials made available for all drugs in current use."
For tips on flu prevention, see the U.S. Centers for Disease Control and Prevention (http://www.cdc.gov/flu/protect/whoshouldvax.htm ).
SOURCES: April 10, 2014, Economic Voice; NBC News; BMJ, news release, April 10, 2014