Women are underrepresented in clinical trials for heart failure, coronary artery disease and acute coronary syndrome but proportionately or overrepresented in trials for hypertension, atrial fibrillation and pulmonary arterial hypertension, when compared to incidence or prevalence of women within each disease population, according to a study published April 30 in the Journal of the American College of Cardiology.

Researchers examined the numbers of women and men who participated in cardiovascular trials submitted to the U.S. Food and Drug Administration (FDA) supporting new drug application approvals. Between Jan. 1, 2005 and Sept. 15, 2015, 36 approvals of 35 drugs for acute coronary syndrome/myocardial infarction, atrial fibrillation, coronary artery disease including angina, heart failure, hypertension and pulmonary arterial hypertension, were reviewed.

Estimates for the participation of women were calculated by dividing the percentage of women among trial participants by the percentage of women in the disease population, with a range between 0.8 and 1.2 reflecting proportional representation. In total, the proportion of women enrolled ranged from 22 to 81 percent, with a mean of 46 percent.

The ratio for atrial fibrillation was 0.8-1.1, 0.9 for hypertension, and 1.4 for pulmonary arterial hypertension – all within or above the desirable range. Heart failure, coronary artery disease and acute coronary syndrome/myocardial infarction were all under the desired ratio level, at 0.5-0.6, 0.6 and 0.6, respectively. Researchers also looked at the gender differences in efficacy or safety, but found little indication of clinically meaningful differences.

According to the researchers, previous studies have suggested that clinical trial inclusion and exclusion criteria disproportionately exclude women from cardiovascular studies; however, data in this latest study show that the lower enrollment of women reflects the lower number of women referred for pre-trial participation screening. Factors prior to screening, such as the identification of potential trial participants and the ability of a candidate to participate, may be more likely reasons for low enrollment of women.

"Based on this work, future research is needed to identify factors leading to under participation of women in cardiovascular clinical trials, particularly those occurring before screening," writes Pamela Scott, PhD, first author and Director of Research in the FDA Office of Women’s Health. "Research is needed to better define barriers that limit participation of diverse populations, not only of women but of minority and older populations."

In an accompanying editorial comment, Louise Pilote, MD, MPH, PhD, and Valeria Raparelli, MD, PhD, explain there is more progress to be made in the fight against sex and gender disparities. "Patients, researchers and health providers can take action by addressing the alarming gaps in quality and equitable health care for women," they write. "Our mandate as health providers and researchers should be to hone the energy and advance awareness that sex and gender in clinical trials really does matter."

Keywords: Female, Coronary Artery Disease, Incidence, Prevalence, Acute Coronary Syndrome, Atrial Fibrillation, Pharmaceutical Preparations, United States Food and Drug Administration, Myocardial Infarction, Angina Pectoris, Hypertension, Hypertension, Pulmonary, Heart Failure

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