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The doctor-patient relationship is an important part of helping and healing. But it can be hijacked by racial or other biases that either party holds.

A novel study published Monday using the placebo response as a measure of bias shows how patients’ unconscious reactions to their doctor’s gender or race may have lingering physiological effects and even steer health outcomes.


In the study, 187 white women and men had an allergy skin prick test, after which a physician applied an inert skin cream but told the participants it was an antihistamine cream that would ease any allergic reaction. Each interaction was the same — same treatment room, physician medical credentials, and verbal instructions given to the patient — except for physician gender and race. The 13 male and female physicians were either Asian, Black, or white.

White patients who were treated by Black and female health care providers had more significant reactions to the skin test than those treated by white and male doctors, suggesting a bias-based blunting of the placebo response to the skin cream. The results were published in the Proceedings of the National Academy of Sciences.

“Bias is complex,” said Lauren Howe, an associate professor of management at the University of Zurich and lead author of the study.


Although the patients in the study rated women physicians as “warmer” and more competent than men, and Black and Asian providers were rated as warmer and equally competent as white providers, and most patients were highly motivated to control biased responding, “they still showed this reaction underneath the skin, which I think shows the fact that bias really is multifaceted and that the effects of bias can potentially linger.”

Howe said the study focused on white, Asian, and Black physicians because white providers have been historically overrepresented in medicine, and Black and Asian physicians face different stereotypical associations — Asian people often seen as a highly competent “model minority” and Black people facing long-held negative stereotypes. The study was conducted in the San Francisco Bay area, where Asian doctors are nearly as prevalent as white doctors (approximately 30% each of the physician population), while only 2.5% identified as Black.

One reason the researchers undertook the study was to explore the impact of shifting demographics among health care providers that are being spurred by diversity and inclusion initiatives across the health industry. In 2017, for example, women made up 50.7% of U.S. medical school enrollees, surpassing male enrollees for the first time in history. In 2021, women made up 55.5% of medical school enrollees.

A substantial body of research shows that biases held by providers can influence patient care. “Our approach in this study was to look at the opposite,” said Howe: Might biases held by patients affect their responses to treatment?

Bias can be a two-way street, influencing doctors and patients, said Charlotte Blease, a philosopher, interdisciplinary health researcher, and co-founder of the Society of Interdisciplinary Placebo Studies. “We’re not really the best at accessing the subconscious part of ourselves that carries or holds implicit bias. It speaks to the need for representation and true diversity.”

Although this study showed that bias could potentially inhibit a patient’s response to therapy, it could also give some people a boost in their care through nothing the provider is doing aside from the color of their skin or their sex, Blease pointed out, adding that this study is part of a necessary conversation “about social justice and the delivery of care that is the makeup of the people who deliver the care.”

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