Women are not represented well enough in clinical trials for many new heart drugs that are used in the support of new drug application (NDA) approvals, according to the authors of a recently published study in the Journal of the American College of Cardiology.

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Assessment of gender differences in treatment response has formed an important part of the drug approval process since the 80s and as such inclusion of women in the study cohort is a necessity. However, underrepresentation of women — particularly in cardiovascular disease (CVD) trials — has been identified as potentially problematic.

In their evaluation, the researchers looked at how many women had participated in trials for cardiovascular drugs that had been used for the submission of NDAs with the FDA between 2005 and 2015. Additionally, for the trials that had available data, they assessed whether the inclusion criteria impacted the proportion of women enrolling in the study.

To determine whether or not the participation of women in the various trials represented a good approximation of the proportion of women affected by the specific disease, the researchers created a ‘participation to prevalence ratio’ (PPR). This PPR was calculated by dividing the percentage of women participating in the trial by the percentage of women among the disease population. If the outcome of that figure was close to one the proportional representation was about right for the specific disease area. If it came out as less than 0.8 it demonstrated an underrepresentation and if it was more than 1.2 it demonstrated an overrepresentation.

On performing this analysis, the researchers found that the representation of women in trials for hypertension and atrial fibrillation (AF) was within the proportional range of disease prevalence, that in pulmonary arterial hypertension (PAH) was slightly over. However, there was underrepresentation in the areas of heart failure (HF), coronary artery disease (CAD) and acute coronary syndrome/myocardial infarction (ACS/MI).

Additionally, the researchers looked to see if there were gender differences in the efficacy and safety profiles of the drugs, however, these differences were found to be minimal.

A limitation of this study was highlighted by the researchers as being that they had only included pivotal studies and as such the results cannot be generalised for all studies (such as early-phase ones).

“In contemporary medicine, neither a pharmacological treatment nor a medical device should be prescribed without a clear evidence of benefit and safety for the patients,” said Dr Louise Pilote, author of an accompanying editorial and a researcher at McGill University Health Center in Montreal Pilote by email when speaking with Reuters. “Therefore, testing drugs or devices in a group of patients that includes an adequate representation of women is a must that we can’t deny to guarantee the best treatment for men and women.”