Despite progress being made against sex bias in clinical studies, preclinical research often relies on male animals or cell lines. To tackle this disparity, the US National Institutes of Health (NIH) are making inclusion of male and female subjects mandatory in NIH-funded studies. Moreover, $10 million in supplemental grants is available to explore sex differences in ongoing preclinical research (1).

We know that drugs can exhibit different rates of metabolism, efficacy and side effects in men and women. “Examples abound of where failure to consider the impact of sex differences have led to harm and/or missed therapeutic opportunities,” says JoAnn Manson, Chief of the Division of Preventive Medicine, Brigham and Women’s Hospital, and Professor of Medicine.
There are also important differences in prevalence and outcomes between men and women in a whole host of common conditions. “Sex differences affect nearly all organ-systems, and differences are particularly prominent in the vascular/cardiac, endocrine, metabolic, brain/neurologic, immunologic, and respiratory systems,” explains Manson. In a recent retrospective study, researchers at Yale University found that among young heart attack patients, women had higher rates of in-hospital mortality, suffered more co-morbidities and stayed longer in hospital than men (2). In fact, the NIH has required the inclusion of women in all NIH-funded clinical research since 1993 – and just over half of clinical trial subjects in NIH-funded trials are now women. It makes sense to now turn the spotlight on preclinical studies, especially given a recent study of published preclinical research in surgery, which found that 22 percent of studies did not report the sex of the animals used and, of those that did, 80 percent used only male animals (17 percent used only females, and only 3 percent included both) (3). “The consideration of sex as a biologic variable in all forms of research is long overdue, and holds promise for new discoveries that will provide clinical benefits for the entire population,” concludes Manson.
References
- NIH Press Release, “New supplemental awards apply sex and gender lens to NIH-funded research”, 23 September (2014). www.nih.gov
- A. Gupta, Y. Wang, J.A. Spertus et al. “Trends in Acute Myocardial Infarction in Young Patients and Differences by Sex and Race, 2001 to 2010”, J. Am. Coll. Cardiol. 64(4), 337-345 (2014).
- D.Y. Yoon, N.A. Mansukhani, V.C. Stubbs et al. “Sex bias exists in basic science and translational surgical research”, Surgery 156 (3), 508–516 (2014).
References
- NIH Press Release, “New supplemental awards apply sex and gender lens to NIH-funded research”, 23 September (2014). www.nih.gov
- A. Gupta, Y. Wang, J.A. Spertus et al. “Trends in Acute Myocardial Infarction in Young Patients and Differences by Sex and Race, 2001 to 2010”, J. Am. Coll. Cardiol. 64(4), 337-345 (2014).
- D.Y. Yoon, N.A. Mansukhani, V.C. Stubbs et al. “Sex bias exists in basic science and translational surgical research”, Surgery 156 (3), 508–516 (2014).