Women aren’t exactly from Venus, but they are different

Women have made strides in almost all aspects of society, yet they’re still discriminated against in healthcare, both in terms of access to life-saving medical products and the safety of drugs and devices.

The theme of International Women’s Day (IWD) is #EmbraceEquity, and as noted on the IWD website “When we embrace equity, we embrace diversity, and we embrace inclusion”.

Embracing equity and diversity is crucial in healthcare and also in health research. Both sex and gender can impact our health and our health outcomes; the former referring to biological attributes, including genetics and reproductive organs, and the latter sexual identity shaped by social and cultural influences that may or may not align with an individual’s biological sex.

A big hurdle in narrowing the sex and gender gap in healthcare is a lack of awareness that a gap even exists, in the understanding of disease and disorders, in medical research and consequently, healthcare treatment.

Young white males are still seen as the “average” human being in healthcare research, which has meant male cells and animals are most commonly used in biomedical research and preclinical studies and females may be excluded from clinical trials.

Even in 2023 clinical trials might only recruit male participants or not consider sex differences in their data. For instance: only 4% of the more than 4,000 COVID-19 clinical studies performed in the US in 2020 planned to analyse sex differences, despite clear evidence of sex differences in terms of infection rates, mortality, and drug responses.

During our research, we came across ads for clinical trials in New Zealand in 2022 for which only male participants were eligible. Yet one was to test a drug delivery system used for patients with breast cancer, and the other to test the safety of a new drug related to breast and stomach cancers.

Female biology is different from male biology, and not just in the obvious, physically manifest ways. Sex hormones and the fluctuations of these throughout a woman’s lifetime and during the menstrual cycle influence a huge range of processes in our bodies. This complicates things, and the extra time and money needed to include women in trials has put researchers off. We’re effectively put in the ‘too hard basket’. Common sense might suggest the fact that men and women are different is a pretty good reason for why we should be testing things equally on men and women.

Common sense would also suggest that it would be useful to test new drugs on women before they’ve been released to market. According to 2022 data from the FDA’s Office of Women’s Health, females have nearly double the risk of developing an adverse drug reaction compared to men. A US report released in 2001 showed that most drugs – 8 out of 10 over a three-year period – were withdrawn due to adverse effects in women.

There are many known differences in how male and female bodies work. These differences exist not just in the way we look, and our reproductive capacities, but right across the scales of biology, at a cellular and genetic level, in the shape of our organs and in how things function. This can result in differences in susceptibility to diseases, symptoms in each disease, and responses to a given treatment.

Cardiovascular disease is often thought to be a ‘male’ disease but it’s the number one killer for both men and women globally and is responsible for the death of twice as many women in NZ than any other single cause.

The female heart is about 75 percent of the size of an average male heart, but current diagnostic criteria for some cardiovascular disorders, such as enlarged hearts are not sex specific. One example, a condition known as hypertrophic cardiomyopathy, results in a thickening of the ventricular wall, the wall between two sides of the heart. This disease is diagnosed when the wall thickness increases to 15 mm, but female hearts are smaller, so men are diagnosed earlier and with less severe symptoms than women.

Smoking-related diseases such as lung cancer were predominantly diseases in men just a few decades ago, but as smoking rates in women have increased these diseases are at least as, if not more, common in women.

Yet women have not been as well represented in the landmark lung cancer screening trials around the world, so differences between males and females are not well understood. Yet women are more likely to be diagnosed with lung cancer at a younger age than men, have a family history of cancer, and lack a smoking history. Lung cancer is the leading cause of death for Māori women and the second leading cause of death for Māori men after cardiovascular disease.

The roll out of a potential lung cancer screening programme in New Zealand must ensure sex differences are considered when defining these screening guidelines.

A woman’s immune system works differently, with females having stronger immune responses than males. This should be a good thing but could also be why 80 percent of people with autoimmune diseases are women. The different immune systems of men and women can impact susceptibility to certain diseases and can affect the efficacy of vaccinations.

Asthma, for instance – which is caused by an overactive immune response - is known to be more common in boys until after puberty, when girls are more likely to suffer from it. The differences in the immune system have also been implicated in Covid-19 where male patients were shown to have higher odds of ICU admission.

While in the past the differences between the hearts and brains of men and women have been over-played (that, for instance, women had smaller brains and therefore less intelligence) and unsurprisingly and importantly there has been a push back that there are any biological differences between the brains and hearts of men and women.

What we do know is that younger women have a lower risk of stroke than younger men, yet women over the age of 65 have two to three times more strokes than men, and those strokes are considerably more likely to be fatal in women than in men. Women are at higher risk of brain aneurysms and of subarachnoid haemorrhage while men have higher rates of haemorrhagic stroke.

There are too many differences to describe here, but some of the above examples illustrate how harmful neglecting these differences in any health-related research and practice can be, contributing to an ongoing lack of equity, affecting both males and females.