For the 62 million or so Americans flattened by flu annually, Tamiflu (or oeseltamivir), promises relief. University of Georgia research finds the medication may not be as beneficial as doctors and patients hope, according to a UGA press release.
“Based on published trials and the conventional wisdom, we thought Tamiflu prevents complications, prevents hospitalizations and is especially good in the vulnerable populations, but we didn’t find support for any of that,” said Mark Ebell, associate professor of epidemiology in the UGA College of Public Health.
"The findings were based on a meta-analysis of three published and eight unpublished double-blind, placebo-controlled clinical trials of Tamiflu that took place in several countries between 1997-2000," the release says.
Study results will appear in an upcoming issue of Family Practice. Advance access is available online.
Other reviews have reported that Tamiflu reduces complications, but Ebell's analysis didn't find this. His team didn't include acute bronchitis, a self-limiting viral illness, as a complication. It considered only pneumonia, sinusitis and otitis media as complications requiring antibiotics.
“We saw a small difference in the likelihood that pneumonia would develop in those patients who were later confirmed to have influenza, but it was only a 0.9 percent reduction,” Ebell said. “However, if you look at all patients given oseltamivir for suspected influenza, which is what happens in practice, there was no difference in pneumonia. So, we found no real difference in the likelihood of important complications.”
The UGA team also looked at how long the symptoms lasted.
“When we looked at the data, it was actually pretty disappointing,” Ebell said. “In the published studies, there appeared to be about a 30-hour benefit for people with confirmed influenza, but when we looked at all the data and looked at who would be given the drug in the primary care office with suspected flu, there was only about a 20-hour benefit.”
For patients who waited longer than 24 hours to seek care, the benefits decreased drastically, which "makes sense based on what we know about how the drug works,” Ebell said.
Tamiflu stops respiratory cells from bursting open and releasing viral particles. Once cells start to burst, the medication loses its effectiveness. Too often, physicians will write prescriptions after the 24-hour window of treatment has closed, Ebell said.
“The potential harm is the development of influenza viruses resistant to Tamiflu,” he said, “as well as the cost, which is not trivial, the side effects of the drug” and the overuse of drugs for an illness that—in most sufferers—will have run its course in a short time period.
While most of the trials enrolled people who were generally healthy, two studies selectively included people more than 65, and another looked specifically at patients with cardiopulmonary disease.
“Those are really important populations to study because, as doctors, we sure hope (Tamiflu) helps those folks who are most vulnerable: elderly, those with chronic disease and children,” he said.
However, these studies were not published. Neither found a reduction in complications in these high-risk populations. Overall, hospitalizations were uncommon, reported for only 33 of the 2,633 patients treated with Tamiflu and just 22 of the 1,694 patients given the placebo.
The complete journal article is available online by clicking here.