The truth about Tamiflu

This week, the BMJ published a series of articles online about an update of an earlier review on oseltamivir’s efficacy in preventing complications from seasonal influenza. What makes it interesting is that in addition to the review itself, the journal also published an article that documents how the reviewers reached its current conclusion that has undermined previous findings for oseltamivir’s prevention of complications from influenza.

The story began
With the spread of the influenza A/H1N1 pandemic that began in April 2009, the use of antiviral drug has increased dramatically, the UK National Institute of Health Research commissioned an update of the Cochrane review of neuraminidase inhibitors such as Oseltamivir ( also known as Tamiflu) in healthy adults.

The Cochrane group that reviewed the efficacy of the antiflu drug in 2005, concluded at the time that oseltamivir was effective in reducing complications of flu among healthy adults. The review was criticised by a Japanese paediatrician, K Hayashi, who questioned the validity and reliability of the findings because one of the papers the review was based on was a meta-analysis of 10 trials of oseltamivir, all of which were funded by Roche, the drug manufacturer, only 2 were published in peer-reviewed journals while the remaining 8 were unpublished or published as abstract only. Hayashi challenged them to “appraise the 8 trials rigidly”.

The review team contacted the authors of the study and Roche with an attempt to verify the data but they said Roche failed to make the data available in the public domain. Eventually the team had to exclude the 8 trials in the new review, based on 20 trials, they found that there was little evidence that Tamiflu has effects on preventing complications like pneumonia and it can cut the length of illness by around a day. They call on governments to set up studies to monitor the drugs for safety.

Some critics say the new finding is not very new, it is generally known the evidence for prevention of flu complications is weak, many clinicians do not recommend the drug for healthy adults. However, others said in severely ill patients with flu-like symptoms, evidence shows that it offers some benefits.

The editor of BMJ said “Government around the world have spent billions of pounds on a drug that the scientific community now finds itself unable to judge”. The new review casts doubt not only in how safe and effective Tamiflu is but also how drugs are regulated and approved.

In the UK, the British government has stockpiled tens of millions of Tamiflu doses and the drug is given to healthy people with flu via a national swine flu hotline.

Source:
"Neuraminidase inhibitors for preventing and treating influenza in healthy adults: systematic review and meta-analysis". BMJ 2009;339:b5106

Editorial : "Why don’t we have all the evidence on oseltamivir"? BMJ 2009;339:b5351