Covid-19 affects men and women differently. So why aren’t gender data reported in clinical trials?

Researchers have learned about the “selectivity” of the coronavirus. It affects men and women differently. Hospital admissions and mortality rates are higher among men than among women. But what many scientists don’t understand is why even the largest covid-19 studies have omitted gender analysis.

Covid-19 affects people differently depending on their gender. Globally, for every 10 women admitted to intensive care units diagnosed with covid-19, there are 18 male hospitalizations, and for every 10 deaths from covid-19 among women, there are 15 male deaths. According to the US Centers for Disease Control and Prevention, there is a gender gap in vaccination rates, with women ahead of men by 6 percent. We add that the rare side effects of the AstraZeneca vaccine appear to be more common among women, while the side effects to the Pfizer-BioNTech and Moderna vaccines are more common among young men.

However, as reported in an article published today in Nature Communications, of 45 randomized controlled trials on covid-19 that were published up to December 2020, only eight noted the effect of gender or gender. The rest of the recent data show no disaggregation by sex or gender, even with a simple count of infections and vaccinations.

Lead author Sabine Oertelt-Prigione, a gender and health researcher at the University of Nijmegen Medical Center, is disappointed with the results of her group’s research. “I thought [gender] would be mentioned in the research, it’s an obvious piece of the puzzle,” she says. This oversight is potentially dangerous in drug trials, which can have different effects on men and women given their physiological differences, says Ortelt-Prigone. And it also deprives us of the ability to know how the disease works, adds Susan Phillips, an epidemiologist at Queens University, who was not involved in the study.

Martin Landray of Oxford University also finds the lack of attention to gender issues surprising. He spearheaded a study on recovery from covid-19 in the United Kingdom, showing a reduction in the risk of death with the anti-inflammatory drug tocilizumab and examining results by gender (although no data worthy of publication were found). “I just thought it was taken into account by everyone,” he says. However, Phillips notes that researchers have often overlooked gender analysis in published clinical studies for over thirty years. “The problem is still there,” she says. “And that makes the article important.”

Ortelt-Prjone’s group sampled all covid-19 articles published before December 15, 2020, excluding commentary, observational and other studies, on PubMed, identifying 45 randomized controlled trials of potential treatments and vaccines. All studies reported the number of male and female participants, but only eight examined the difference in outcomes between men and women, the group found.

Even the largest covid-19 studies have sometimes omitted gender analysis. For example, large-scale vaccine trials by Pfizer-BioNTech and Moderna examined gender differences in vaccine efficacy, finding more than 90% efficacy in both men and women. But none of the trials showed gender-specific side effects, UN University gender and health researcher Lavanya Vijayasingham and colleagues said in a March article in The Lancet. Even if such data is not published in scientific journals, it is still collected and monitored, but a small number of serious side effects could mean no significant gender difference, says Stephen Thomas, lead researcher for Pfizer vaccine trials, of the Medical University of New York. York.

The findings of the new article are consistent with other reviews. A small review of covid-19 studies recently published in EClinicalMedicine found that none of the thirty studies examined the effects of gender on outcomes. And an April article in BMJ Global Health, which looked at a wider range of articles on covid-19, including observational studies, found that only 14 of 121 articles analyzed the effect of gender on outcomes.

Sometimes there may be reasons for not reporting sex-disaggregated data. The study of tocilizumab conducted by Lendray’s group found the only statistically significant difference between the sexes: in patients who were not already ventilated at the beginning of the study, tocilizumab generally reduced both the risk of death and the need for mechanical ventilation, but analgesia from gender, found differences only among men. But for other outcomes, such as hospital discharge within a month, there was no statistically significant difference between the sexes. The team concluded that there was no “compelling evidence for sex differences,” and therefore did not publish it, says Landray.

He notes that making assumptions about the difference between the sexes, where it may not be, can be harmful. For example, studies in a small number of women have shown that taking aspirin with them does not prevent heart attacks and strokes, but limiting drug use based on such weak evidence could deprive women of a potentially effective drug, Lendray said.

Researchers are now deciding whether to include gender and gender in their analyzes, says epidemiologist Emily Smith of George Washington University. But, “perhaps the intervention of the system can help solve this problem,” – she said. If research foundations or registries require sex-disaggregated reporting, this may encourage researchers to use it.

The lack of data goes beyond clinical trials: in the latest monthly report based on the Gender, Gender and Covid-19 project database of the Global Health 50/50 non-profit organization, from 198 countries, only 37% report death data and only 18% report death data. vaccinations disaggregated by sex. According to the same report, only Austria and two Indian states provided data on non-binary genders, although some US states also reported cases of non-binary or transgender identities.

The covid-19 pandemic “has shed light on the importance of gender and gender in a way that only a few other cases have been able to do,” says Sarah Hawkes, co-director of Global Health 50/50. She and others point out that it’s time to clarify these differences through research.

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