Skeptical Raptor's Blog hunting pseudoscience in the internet jungle

Tamiflu-does it work

According to the CDC, this year’s flu season is pretty serious in the USA. Current data, shows that about 4.6% of patient visits to health care providers are for influenza like illnesses (ILI). Thirty states and New York City are now reporting high ILI activity; an increase from 24 states last week. Additionally, 10 states are reporting moderate levels of ILI activity. Forty-eight states reported widespread geographic influenza activity for the week of January 6-12, 2013. This increased from 47 states in the previous week. 

2013-flu-outbreak-week-03

 

Although there has been a slight drop-off in ILI visits over the past couple of weeks since the peak in early January, the CDC continues to identify this season as a “moderately severe” one, and supplies in some areas have tight supplies of the flu vaccine. 

The CDC recommends anti-viral drugs if you do get the flu, mainly because there are small, but significant risks from the flu for all individuals, especially pregnant women, those older than 65, those younger than 5 (especially younger than 2), and those with certain acute and chronic medical conditions. (There is a myth that only the very young or very old need to get the flu vaccine, don’t believe it.) And the potential risks from the flu can be anything from miscarriage for a pregnant woman to death for someone with heart disease. The flu is not a trivial disease.

One of the more popular (and most advertised) anti-viral drugs for the flu is Tamiflu (oseltamivir), manufactured by Genentech, a part of the Swiss pharmaceutical giant, Hoffman-La Roche. Oseltamivir may slow the spread of the influenza virus between cells in the body by stopping it from chemically cutting ties with its host cell.

However, the evidence for its usefulness seems to be less than overwhelming. Several recent articles in the Cochrane Reviews, which I consider to be the “gold standard” of meta reviews of clinical trials provide less than favorable assessments of the drug:

  • In a review of randomized clinical trials in adults, the authors conclude that “numerous inconsistencies detected in the available evidence, followed by an inability to adequately access the data, has undermined confidence in our previous conclusions for oseltamivir.”
  • In a similar review in children, the authors similarly conclude that the drug provides “modest benefit in reducing duration of illness in children with influenza. However, our analysis was limited by small sample sizes and an inability to pool data from different studies. In addition, the inclusion of data from published trials only may have resulted in significant publication bias.”

Overall, the studies did not show any decrease in the rate of hospitalization, an expected endpoint of taking the medication (and a known risk of influenza). Furthermore, the authors stated that during the “conduct and reporting of the trial programme, the data available to us lacked sufficient detail to credibly assess a possible effect of oseltamivir on complications and viral transmission.” So, the data could not tell the authors if drug worked, if it reduced complications, or if it did anything at all.

And the potential of “publication bias” indicates that the Cochrane Reviews authors appear to think that Hoffman-La Roche are presenting just the data that support the efficacy of their drug. Not all pharmaceutical companies think this is the best way to present their data, maybe not even Roche usually.

The authors requested more information from Roche. They didn’t get anything.

This isn’t the way a pharmaceutical company should work. This is how supplement companies work. Provide positive evidence, but suppress everything else, so we really don’t know if it works or it doesn’t. The best we know is that Tamiflu reduces the course of flu by one day. Well, that’s not very impressive, considering the expense of the drug (well over $100 if you’re paying out of pocket). I would argue that a one day improvement in symptoms is about what would be expected of a placebo.

Get the flu shot. It’s a much better bet.

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