This news release focuses on an observational study, published in The Journal of Infectious Diseases which reports that treating pregnant women hospitalized with severe influenza in the early stages of illness with oseltamivir (sold under the brand name Tamiflu) appears to significantly reduce the patient’s time in the hospital. The study also found that pregnant women who were hospitalized with severe flu were less likely to have been vaccinated, compared to women hospitalized with milder flu. The release covers some of the bases when explaining the study and benefits, but neglected to address potential harms that were noted in the published study and to provide needed context on the absolute risk of contracting serious influenza during early pregnancy and absolute rates of risk reductions.
Influenza, or “the flu,” is a widespread disease in the United States. The CDC reports that about 40 million people in the U.S. got the flu during the 2014-15 flu season, of which 970,000 required hospitalization. And the health risks associated with flu are significant for pregnant women and their unborn children. As the CDC notes: “Changes in the immune system, heart, and lungs during pregnancy make pregnant women (and women up to two weeks postpartum) more prone to severe illness from flu, as well as to hospitalizations and even death. Pregnant women with flu also have a greater chance for serious problems for their unborn baby, including premature labor and delivery.” The research findings inform treatment and preventative care of an at-risk population — pregnant women — for a widespread and dangerous disease. That deserves our attention. At the same time, we expect experts to inform us about the true nature of the risks to pregnant women and their unborn children.
The safety and effectiveness of oseltamivir in treating influenza remains a controversial topic within the medical community. Following an exhaustive review of the oseltamivir clinical trials (which it had to fight for years to obtain), the Cochrane Collaboration along with the British Medical Journal (BMJ) issued a report in 2014 that strongly questioned oseltamivir’s safety and effectiveness in combating influenza. “Initially thought to reduce hospitalisations and serious complications from influenza, the review highlights that Tamiflu is not proven to do this, and it also seems to lead to harmful effects that were not fully reported in the original publications,” wrote Cochrane editor-in-chief Dr. David Tovey, “This shows the importance of ensuring that trial data are transparent and accessible.”
The release focuses primarily on using the antiviral drug oseltamivir to treat pregnant flu patients who have been hospitalized. A course of oseltamivir often costs more than $100. For patients with limited resources, or without good insurance coverage, cost could be a factor. And because the drug is on the market, the release could have addressed this with a sentence or two. The release also discusses the importance of vaccination, without addressing cost.
The release is a mixed bag here. The release adequately describes some aspects of the benefits. For example, pregnant women hospitalized with severe flu that were given oseltamivir within two days of exhibiting flu symptoms spent a median of 2.2 days in the hospital; as compared to 7.8 days for pregnant women hospitalized with severe flu that were given oseltamivir more than two days after exhibiting flu symptoms. In addition, the release addresses the benefit of vaccination by saying: “pregnant women hospitalized with severe flu illness were half as likely to have been vaccinated as women hospitalized with milder illness (14 percent vs. 26 percent).” But the release would have been stronger if it had done a couple additional things.
First, the release notes that “Pregnant women hospitalized with less severe illness who were treated early also had a shorter hospital stay than those treated later, but the difference was not as great.” If you’re going to mention this benefit at all, even using modest language, it would be better to put a number to it. (Was it a difference of a day? 0.2 days?) Also, the release specifically mentions “serious illness and complications, including death” in its opening paragraph — but never tells readers whether the study found any potential connection between early antiviral treatment and reduced risk of complications for mother or child. Even if the study didn’t find any such relationship, the release could have said that.
The release does not address potential harms at all and that is an important omission considering the strong disagreement over the drug’s side effects and effectiveness. The Centers for Disease Control and Prevention (CDC) and the Mayo Clinic both stress that the risks associated with oseltamivir are far outweighed by the benefits of using it to treat flu during pregnancy. And studies (like this one from 2010 or this one from 2013) have found no evidence that oseltamivir hurts the pregnancy or the unborn child. However, the Cochrane Collaboration, which reviewed numerous trial data found “The use of oseltamivir increases the risk of adverse effects, such as nausea, vomiting, psychiatric effects and renal events in adults and vomiting in children.” The study itself even acknowledged that the health risk to fetuses is unknown. “…the study does not answer the question as to whether early treatment is associated with lower rates of important adverse outcomes such as stillbirths and maternal deaths,” the study states in a section describing limitations.
The medical society was remiss in not acknowledging the unknown safety issues and that health experts are in disagreement over oseltamivir’s safety and effectiveness.
There is no discussion of the study’s limitations. To start with, it is observational study, not an experimental one which seeks to show cause and effect. The study doesn’t describe whether the antiviral was provided before or after the hospitalization or differentiate the outcomes when the drug was administered at 49 hours or at 72 hours or more. These are details that should have been noted and explained.
While the release does make the distinction that the number of women in the “severe” group was a very small percentage of the overall cohort (64 out of 865, or 7 percent) it omitted an explanation of what “severe” flu meant, relative to “less severe” flu — particularly given that all of the women in the study were hospitalized. It would also have been good to explain why the researchers split the women into two groups. From an outside perspective, it could look like an arbitrary decision to split the cohort into different groups in order to get a robust statistical result. Some explanation would help here.
Influenza can be a serious illness during pregnancy and the release treats it accordingly so on that point we rate it satisfactory. However, the absolute rates of complications among pregnant women with influenza are missing so it’s hard to gauge the true seriousness and rates of hospitalization without this context.
The release doesn’t articulate funding sources or conflicts of interest. We have to assume the study was sponsored by the CDC because the lead author quoted works there. We are sometimes surprised when a news release fails to mention that there were no conflicts of interest. This is important information, and can only improve one’s perception of the research. Why not mention it? When we looked at the published study we read that the study authors have no conflicts to declare.
Oseltamivir is one of two FDA approved antivirals for treating influenza. The other is zanamivir. The FDA has taken a very murky approach to recommending these drugs during pregnancy. The FDA website states, “Both drugs are designated “Pregnancy Category C,” which means that they have not been studied in pregnant women. However, Pregnancy Category C does NOT mean the drug cannot be used in pregnant women. Pregnant women can and should receive a category C drug when the possible benefits of using the drug are more likely than the possible risk of harm to the woman or her baby.”
The release could have acknowledged the existence of zanamivir and whether similar observations were made about its effectiveness.
Readers can infer that oseltamivir is available, since it was used in hospitals to treat patients.
The release establishes that previous studies have suggested antiviral therapy is beneficial in this patient group, and that this study supports the CDC’s recommendation that symptomatic influenza in those with high risk of complications should be treated within the first 48 hours.
The journal article itself notes that “This is the first and largest study to report on clinical characteristics and outcomes of pregnant women hospitalized with laboratory-confirmed influenza since the 2009 pandemic;” and that “our study is the first to assess the impact of early vs. late antiviral treatment on [length of hospital stay] among pregnant women hospitalized with severe and non-severe influenza.”
The release doesn’t go overboard with unjustifiable language.