Flu drugs are not (that) effective ... when assessed properly

From Fivethirtyeight.com

The CDC released figures Thursday showing that this season’s influenza vaccine is only about 23 percent effective, and the federal agency recently sent a letter to doctors, urging them to write more prescriptions for influenza drugs.

“Antiviral flu medicines are underutilized. If you get them early, they could keep you out of the hospital and might even save your life,” CDC Director Tom Frieden told reporters Jan. 9. Flu season lasts, on average, about 13 weeks. We’re about midway through a particularly bad one.

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The discrepancy between the CDC’s assertion that the flu drugs can prevent complications, hospitalizations and perhaps deaths, and the FDA’s insistence that the drugs have only been shown to cut the amount of time that symptoms persist comes down to how they weigh the evidence. The FDA requires randomized clinical trials, the gold standard of evidence in medicine, while the CDC also relies on non-randomized reports. “Observational studies from many countries have consistently found that early oseltamivir [Tamiflu] treatment of influenza patients reduces the duration of hospitalization and risk of severe outcomes such as intensive care unit admission or death,” CDC spokeswoman H. Amy Rowland told FiveThirtyEight in a statement.

But physician Tom Jefferson of the Cochrane Collaboration, an international organization that assesses medical evidence, calls the studies that the CDC is using to tout the drugs poorly designed and unreliable, pointing out that they’re funded by the drugs’ maker and led by researchers tied to the manufacturers. More rigorously designed trials do not back them up. For example, a study published last month that randomly assigned 400 hospitalized patients to receive either the newly approved peramivir (Rapivab) or a placebo was halted early for “futility”when it became clear that patients receiving the drug weren’t benefitting.

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And if the drugs are simply reducing fevers and making people feel better via some other mechanism, then it’s possible they’re nothing more than expensive alternatives to acetaminophen and ibuprofen, which alleviate aches and reduce fevers. (Tamiflu retails for about $130, Relenza goes for about $67, and Rapivab costs about $1,000.) Right now, there’s not enough evidence to draw firm conclusions on the drug’s actual mechanism of action, and Jefferson, his colleagues at Cochrane and editors at the British medical journal BMJ are embroiled in a years-long effort to obtain complete clinical trials data from the maker of Tamiflu.