TUESDAY, Dec. 8, 2009 (HealthDay News) -- No evidence exists that the widely used influenza drug Tamiflu prevents pneumonia or other complications in otherwise healthy patients who come down with the flu, a new review contends.
Claims about the effectiveness of the antiviral drug against flu-related complications have influenced governments worldwide to stockpile Tamiflu (oseltamivir) as part of their preparations for a global pandemic, the review authors said.
"Governments around the world have spent billions of [dollars] on a drug that the scientific community now finds itself unable to judge," said Dr. Fiona Godlee, editor-in-chief of the British Medical Journal, which published the article online Wednesday. The review was done by BMJ and Channel 4 News in Great Britain.
The authors of the new review, which updates a review published in 2006, analyzed 20 published clinical trials of Tamiflu that examined prevention, treatment and adverse reactions. However, the analysis was hampered by the "paucity of good data" available from the trial authors and Roche, the maker of Tamiflu, the study authors said.
This meant the review authors couldn't verify the results of eight important trials that were never fully published. These eight trials, which were included in the previous review, were omitted from the new review.
Based on the data available to them, the authors of the new review concluded they have "no confidence in claims that Tamiflu reduces the risk of complications of influenza in otherwise healthy adults," and said the drug should not be used in routine control of seasonal flu.
Because previous evidence about Tamiflu's effects on flu complications may be unreliable, governments should establish studies to monitor the safety of Tamiflu and other neuraminidase inhibitors, said review leader Chris Del Marr, a professor at Bond University in Australia, and colleagues.
The review findings call into question "not only the effectiveness of oseltamivir but the whole system by which drugs are evaluated, regulated and promoted," Godlee and a BMJ colleague wrote in an accompanying editorial.
"Once a trial is completed, there needs to be ready access to the raw data behind any analyses used to license and market a drug," they said.
In response to the study, Roche officials said they "firmly believe in the robustness of the data" on Tamflu, and full access to trial data has been given to governments and regulatory authorities. The company also said it will make all study summaries of Tamiflu -- including key data -- available on a password-protected Web site, according to a BMJ news release.
The World Health Organization said Tuesday that data from countries around the world show that when given early, Tamiflu can reduce the severity of swine flu symptoms. Still, the agency recommends the drug be saved for people at risk of complications, such as pregnant women, the elderly, children, and those with chronic health problems, the Associated Press reported.
"This will not change our (Tamiflu) guidelines," said Charles Penn, a WHO antivirals expert.
Penn said that while previous studies have found that Tamiflu only offers a modest benefit, when patients with severe illness or those at risk of complications are treated early, fewer hospitalizations and deaths result, the AP said.
The U.S. National Library of Medicine has more about Tamiflu.