Breaking the bias in women’s healthcare

Marta Uncio Ribera is a biomedical engineer at 42 Technology with a focus on medical device development and particular expertise in the biomechanics of prosthetics. She outlines the data bias that exists when it comes to developing medical devices for women.

Although women make up half the world’s population, women’s health issues are often considered niche.

In writer Caroline Criado-Perez’s words, they are being overlooked by healthcare systems, leaving women “misunderstood, mistreated and misdiagnosed.” Bias in research data itself is holding back development of safe and effective medical devices and treatments for women. The first step to overcome this challenge is awareness of the data gap.

Women’s health is a term that is often misunderstood - it does not only cover female-specific conditions. It encompasses a much broader spectrum, including conditions that disproportionately or more severely affect women, and ones that have different symptoms, outcomes or treatment options and efficacies. 

Why is there a data bias?

Exclusion from research

Up until the 1990s, women were systematically excluded from biomedical research which has led to a significant data gap. The rationale was that female hormonal fluctuations increased complexity, and that performing research on women of childbearing age introduced medical and liability concerns.

But results from these clinical studies (performed mostly in male subjects) were then extrapolated to females. Ironically, after justifying their exclusion due to differences in hormonal cycles, it was assumed that medical treatments would work equally in male and female bodies. In some high-profile cases, such as Ambien sleeping pills, this has proven deadly.

Lack of funding

There has also been a considerable lack in research funding for women’s health issues. In the case of endometriosis, limited research and awareness means that, according to the UK government, it takes women on average 7-8 years to be diagnosed. Endometriosis, which is estimated to affect 10% of women of reproductive age, is a condition in which tissue similar to the uterus lining tissue grows in regions where it shouldn’t do - like the ovaries or fallopian tubes. It can lead to agonising pain and fertility loss. But in a study by Alliance for Endometriosis, 90% of patients reported people are “dismissive or even disbelieving” of their monthly symptoms.

No sex- and gender-disaggregated data

Even if the participation of women in clinical studies has increased in recent years, data still fails to be sex- and gender-disaggregated. Disaggregating data involves collecting, analysing, and reporting sex and gender specific data to investigate potential differences and similarities.

Consequences of the data bias

Research has repeatedly shown that sex is a variable that can influence disease epidemiology, manifestation, diagnosis, treatment, and outcomes. The lack of data or awareness about these potential differences can lead to misdiagnoses, adverse drug reactions and ineffective, unsuitable, or dangerous medical devices. Examples are numerous, but I have picked out a few that we can learn from.

Implantable defibrillators

Studies have shown that being female is a risk factor during primary pacemaker implantation, independent of age or device type.

In the case of cardiac resynchronisation therapy devices (CRT-D), this is not surprising: women made up only around 20% of trial participants. CRT-D are implantable defibrillators that correct irregular heart rhythms in patients with heart failure. The FDA guidelines only recommended their use for patients with a QRS complex over 150 ms (the electrical impulse that starts just before ventricular contraction). This worked for men. But it has since been found that women with a QRS complex between 130 and 149 ms benefited from a CRT-D more than men and experienced a 76% reduction in heart failure or death.

Hip implants

With metal-on-metal hip resurfacing implants, women have a much higher risk of adverse local tissue reaction, dislocation, and aseptic loosening, as well as being more likely to need a surgical revision, according to research.

Hip implants are gender neutral: although they come in a range of sizes, they don’t necessarily consider biomechanical differences between male and female bodies. Kinematic differences can cause increased edge-loading risk in females, for example when standing up from sitting. Edge loading increases wear, which produces metal debris and can cause inflammatory reactions. 

Heart attacks 

Cardiovascular disease is often considered a men’s health issue but according to the WHO, it is the leading cause of mortality for women in Europe.

Research funded by the British Heart Foundation shows that women are more likely to experience different symptoms – shortness of breath, nausea, vomiting and back or jaw pain – so are 50% more likely to be initially diagnosed incorrectly. And an initial misdiagnosis increases the risk of death by 70%. A lack of awareness of these symptoms, in both medical staff and patients, means that misdiagnoses continue to occur – and women are dying.

What can we do about it?

Slowly, more regulators and organisations have acknowledged the existence and consequences of this bias. But companies developing treatments and devices have a responsibility too.

As engineers, we should always design for the intended users – a diverse mix of trial participants, representative of the intended patient population, should be recruited for ethnographic research. Manufacturers cannot rely on biased historical data to inform the device design.

When analysing test or trial results, data must be disaggregated to look out for differences across patient and user groups that might have been missed in the design process. This doesn’t mean just dividing the population into male and female: biases exist across the board – gender, race, age, economic background, sexual orientation – and they can all impact device performance. Disaggregation of data is about taking everyone into account.

Opportunities for innovation

Women’s health promises to be a huge area of growth. A range of new companies are targeting issues that affect women, so have traditionally been neglected for the reasons discussed above – lack of research, lack of funding and lack of data.

For example, Embr Wave has developed a wearable that achieves hot flush relief to help women going through menopause. Elvie is revolutionising the breast pump market with its wearable electric breast pump, which enables users to discreetly collect breast milk. And Micrima has developed a novel breast scanning system that uses radio wave technology to improve breast cancer detection.

There is no reason not to innovate in women’s health, to disaggregate data and to break the bias. To request a list of references for the data quoted here please contact answers@42t.com