Medical Research Should Include More Women Participants and Examine the Role of Gender in Disease Incidence and Treatment

(mdash) Are the health needs of women adequately addressed by medical research as it is currently conducted? In the May issue of Mayo Clinic Proceedings, a team of Australian researchers and two cardiologists closely examine this question.

"The traditional model of medical research was limited by gender and racial blindness and assumed that results of research on white male participants could be easily extrapolated to female and minority populations," write Wendy Rogers, B.M.B.S., Ph.D., and Angela Ballantyne, Ph.D., from the School of Medicine at Flinders University in Adelaide, Australia. The researchers say a growing body of evidence shows important differences between men and women related to the incidence of certain diseases, how they respond to treatment and the long-term outcomes.

Drs. Rogers and Ballantyne reviewed 400 clinical studies that were conducted in Australia and the results were published in journals between Jan. 1, 2003 and May 31, 2006. The research provides data about issues that include: the number of men versus women participating in research on diseases affecting both genders; the number of studies classified as female-only research and male-only research; and the degree to which studies provided gender-specific data and analysis.

"Analysis such as this is essential for determining whether the national research agenda is addressing issues in both men's and women's health and the extent, if any, of inappropriate exclusions of either gender from potentially beneficial research," write Drs. Rogers and Ballantyne.

At first glance, the numbers collected by the Australian team do not suggest that women are under-represented in the research they examined. Of the 546,824 persons studied, 73 percent were female. However, the team points out that these numbers were largely due to the greater number and size of female-only studies. When Drs. Rogers and Ballantyne looked at the type of research in which men and women participated, they discovered that male participants were more than three times as likely to be involved in research into conditions affecting both men and women. Other data provided by the Australian team indicates that gender-specific reporting of results in women is particularly lacking in pharmaceutical research.

"Research on women's health continues to focus predominantly on their reproductive capacity and function, whereas research with men continues to investigate conditions that are not specific to one sex," write Drs. Rogers and Ballantyne. The result, say the authors, is that women are underrepresented in research focusing on significant health issues that are unrelated to biological aspects of reproduction.

Despite the growing literature on the clinical importance of gender, the Australian team noted that the majority of the 400 studies reviewed did not analyze the potential role of participant's gender in their published research. Drs. Rogers and Ballantyne recommend that clinical trials registries collect data on the gender of participants "to facilitate further research in this area and that researchers, journal editors, and peer reviewers work to standardize mechanisms for sex-specific reporting and analysis in publications."

In a companion editorial, cardiologists Sharonne N. Hayes, M.D., director of the Mayo Clinic Women's Heart Clinic, and Rita Redberg, M.D., from the University of California, San Francisco, explore the historical context surrounding the limited role of women participating in medical research and provide additional data that echo the findings of the Australian team.

"We observed the same phenomenon in a recent review of cardiology clinical trials where only 25 percent of all studies reported results by sex. As heart disease is the leading cause of death in women, it is dismaying that data from cardiovascular clinical trials are so limited," write Drs. Hayes and Redberg.

Noting that unexpected gender-based differences have been found in many diseases, including lung cancer, degenerative joint disease, depression and other mental health disorders, Drs. Hayes and Redberg assert that "the lack of sex differences should not be assumed and instead must be systematically studied." Given this information, "analyzing data by sex for conditions or treatments affecting both men and women is the only way we will be able to begin to provide optimal care for all patients," they write.