Women’s involvement in clinical trials: historical perspective and future implications

Background: Women are underrepresented in sacubitril/valsartan (SV) clinical trials. The aim of this study was to assess sex-specific differences in efficacy, tolerability, and safety of SV in real-world heart failure with reduced ejection fraction (HFrEF) patients. Methods: A prospective registry in 10 centers including all patients who started SV during the last 6 months was analyzed in this study. Results: A total of 427 patients were included, 126 (29.5%) were women. There were no substantial differences in HFrEF treatment before SV initiation, although fewer women than men carried an implantable cardioverter defibrillator (57 [45.2%] vs. 173 [58.1%], p = 0.02). SV starting dose was 24/26 mg b.i.d. in 206 patients (48.2%), 49/51 mg b.i.d. in 184 (43.1%), and 97/103 mg b.i.d. in 34 (8.2%), without relevant differences associated to sex. There were no losses during a mean follow-up of 7.0 ± 0.1 months. The proportion of patients who discontinued the drug (16 [12.7%] women vs. 33 [11.0%] men, p = 0.66) or presented SV-related adverse effects (31 [24.6%] women vs. 79 [26.5%] men, p = 0.72) was also similar in both sexes. However, female sex was an independent predictor of functional class improvement in the multivariate analysis (odds ratio 2.33, 95% confidence interval: 1.24–4.38, p = 0.04). Conclusions: SV in women with HFrEF has a similar tolerability as in men. Females seem to have a more frequent functional class improvement than males.

Heart failure (HF) is a complex disease, almost as common in women as in men. Nonetheless, HF clinical presentation, prognosis, and aetiology vary by sex. This review summarizes the current state of sex‐sensitive issues related to HF drugs included in treatment guidelines and suggests future directions for improved care. Heart failure presentation differs between female and male patients: females more often show with hypertensive aetiology and the preserved ejection fraction phenotype, while men more often show ischaemic aetiology and the reduced ejection fraction phenotype. Yet the HF clinical guidelines in Europe, the United States, and Canada do not reflect the sexual dimorphism. Further, in randomized clinical trials of HF medication, women are largely underrepresented, typically consisting of ≥70% men. Given the knowledge that some adverse drug reactions, such as torsade de pointes and angiotensin‐converting enzyme inhibitor‐induced cough, occur more frequently in women, we emphasize the need to test medications thoroughly in both sexes and explore sexual dimorphisms. To better represent all of the targeted patient population and provide better care for all, two kinds of change must come about: recruitment methods to randomized clinical trial samples need to evolve and the participation needs to seem more attractive to women.

Physicians previously perceived heart disease to be a man's disease; yet, since 1984, more women have died of ischemic heart disease. Because women who develop obstructive coronary heart disease and heart failure tend to do so 10 years later than men, cardiology clinical trials that use arbitrary age cutoffs or exclusion criteria based on comorbidities and polypharmacy often limit the pool of potential participants to a greater extent for women. Issues related to trial design and insufficient accounting for female-predominant disease patterns have contributed to low rates of enrollment of women in certain domains of cardiology research. Accordingly, women do not benefit from as rich an evidence base for cardiology as men. Here, we review major sex differences in heart disease and discuss areas of cardiology research in which women have been underrepresented. Considering the widespread sex differences in cardiovascular structure and function, it is important to include balanced numbers of women and men in cardiovascular clinical trials. Beyond inclusion, sex-specific reporting is also essential. Moreover, with ongoing developments of clinical-trial methodology, it is imperative to seek innovative ways to learn as much as possible about how interventions behave in women and men. Adaptive trials are specifically identified as promising opportunities to consider sex-based analyses at interim stages, allowing sex-specific flexibility as these trials unfold. Finally, we emphasize the importance of factoring sex as a biological variable into the design, analysis, and reporting of preclinical research, because this research critically informs the design and execution of clinical trials.