Part one of this blog introduced the ethics of body mass index or BMI recently discussed in the provocatively titled Huff Post article “The BMI is Racist and Useless. Here’s how to Measure Health Instead” by Christine Byrne. In that post, we talked about the historical context for the origins of BMI, a brief history of the Public Health Service, and establishment of the National Institutes of Health (NIH). We also talked about some historic cases of unethical clinical research practices, including the Tuskegee study and Henrietta Lacks, as examples of racism in medicine, which is called medical apartheid.

Now, let’s take a closer look at BMI, which by today’s research standards has a serious flaw.

Our understanding of how BMI relates to human health is extremely biased. It contains a large amount of what is known in statistics as ascertainment bias. This term simply means that a study was done in a way that the results are more relevant to one group than another. In this case, BMI was developed from a group of mostly white males.

How BMI might affect the health of women and non-White, populations is not well understood. The research community at large is beginning to understand that a lack of diversity limits how the results of a study can be applied. Regrettably, like BMI, the majority of all human research has been biased in a similar way.

Fortunately, a debate over the accuracy of BMI emerged. The Centers for Disease Control and Prevention’s (CDC) current guide to physicians ,(Body Mass Index: Considerations for Practitioners), states;

BMI is a surrogate measure of body fatness because it is a measure of excess weight rather than excess body fat.

Factors such as age, sex, ethnicity, and muscle mass can influence the relationship between BMI and body fat. Also, BMI does not distinguish between excess fat, muscle, or bone mass, nor does it provide any indication of the distribution of fat among individuals.

The CDC guidelines show that age, gender, and muscle mass may influence the interpretation of BMI, and give examples of how older adults and women, on average, have more body fat than younger adults and men with equivalent BMI respectively, and that, high BMI in some can be due to increased muscle mass.

BMI is an inaccurate tool being used in ways it was not intended. There are also no standard adjustments being made for factors known to impact how we interpret it. BMI is being applied inappropriately to health, including women’s and reproductive health. Despite these problems, BMI is still commonly used to make treatment decisions where weight is believed to be an important predictor of outcomes. This includes decisions about the suitability of women for IVF treatment despite studies that have shown the relationship between BMI and IVF success varies between ethnic groups. This is a significant concern, because after age, the amount of fat tissue a person carries may be the next most important factor in cases of infertility in both women and men. What impact the misuse of BMI is having on healthcare outcomes in underrepresented and underserved populations is unknown.

BMI is an example of how health disparities between ethnic groups can be hidden, stay unresolved, be worsened, or even created by modern health practices. This has been recently highlighted by the disproportionate mortality rate of African Americans during the COVID-19 pandemic. Reproductive and maternal health disparities, however, are far less frequently discussed. The American College of Obstetrics and Gynecology (ACOG) 2015 committee opinion entitled “Racial and Ethnic Disparities in Obstetrics and Gynecology” reported that Black women had the highest;

• Infertility rate (12%)

• Preterm birth rate (17%)

• Fetal death rate (11/1000 births)

• Maternal death rate (26/100K births)

• Breast cancer death rate (31/100K)

• Diabetes related death rate (33/100K)

• Frequency of cesarean delivery (C-section) (36%)

Additionally, only 75% of births by Black women received first trimester prenatal care. Fewer American Indian and Alaska Native women received care, at a rate of 69%.

There are multiple factors contributing to these disparities including access to healthcare. However, lack of access does not explain all the disparities we see in women under the care of clinicians.

Recently, you may have learned about the tragic story of Dr. Chaniece Wallace. She was the Chief Pediatric Resident at the Indiana University School of Medicine who died following the C-section to deliver her premature daughter after developing preeclampsia late in her pregnancy. This tragedy was clearly not caused by a lack of access to care.

Dr. Wallace’s death was not an isolated incident. The maternal death rate in White women is 7/100K births, making Black women over three times more likely to die during childbirth than their White counterparts.

The misuse of BMI, which was driven by a study with a lack of diversity, we noted is called ascertainment bias. Other types of bias also drive health disparities.

A study published in the Proceedings of the National Academy of Sciences (PNAS) reported that the infant mortality rate is three times higher in Black babies when compared to White ones. Remarkably, this mortality rate is reduced by half when they are cared for by Black doctors. Although medical doctors pledge to do no harm and make the well-being of their patients their top priority, they may still be unconsciously biased.

An article published in 2016 by the American Association of Medical Colleges (AAMC) showed that over half (50%) of first and second year medical students and residents held one or more of the following false beliefs:

“Black people’s nerve endings are less sensitive than white people’s.”

“Black people’s skin is thicker than white people’s.”

“Black people’s blood coagulates more quickly than white people’s.”

These responses from current medical students may seem shocking, but they are frighteningly similar to those of James Marion Sims, the so-called “father of modern gynecology”.

Sims conducted barbaric and unethical surgical experimentation on enslaved African women without their consent or anaesthesia on the plantation he inherited. His view of them as property instead of people eliminated his motivation to obtain their consent, and the racist notion that “Black people didn’t feel pain” justified his inhumane practice of not using anesthesia.

Sims’ work set the tone for over 70 years of federally-funded forced sterilization programs operating in 32 states across the country. Tubal ligations and what were referred to as “Mississippi appendectomies” or unconsented hysterectomies were conducted on African American, Latina, Native American, cognitively impaired, and impoverished women, including the voting and civil rights icon Fannie Lou Hamer.

Christine Byrne’s title “The BMI is Racist…” is unfortunately only the tip of the iceberg reflecting on the atrocities committed against human beings in the name of science, the dark history of the field of medicine, the other federal and state institutions which share a similar history, and the uncomfortable truth about the on principles on which the country was founded.

If you enjoyed this series or want to learn more about topics like this or others discussed in the series, please let us know in the comments.