Whose Blood Pressure? The Untold History of How "Normal" Was Defined — and Who Was Left Out

Every time a nurse wraps a cuff around your arm and reads out a number, that number is being compared against a standard. A threshold. A definition of what is "normal" and what is dangerous.

Most patients never ask where that standard came from. Most providers never explain it.

The answer is a story about who gets counted in medicine — and who gets erased. It is a story about how the most basic measurement in cardiovascular care was built on a foundation that excluded the very communities most harmed by heart disease. And it is a story that is still unfolding today, in the bodies of Black, Latino, Indigenous, and low-income patients who are being measured against a standard that was never built for them.

The modern blood pressure cuff — the sphygmomanometer — was developed in 1896 by Italian physician Scipione Riva-Rocci. The device was refined in the early 1900s by Russian surgeon Nikolai Korotkoff, who identified the sounds used to determine systolic and diastolic pressure.

From the beginning, the populations on whom these measurements were standardized were narrow. The early clinical studies that established baseline blood pressure norms were conducted almost exclusively on European and American men — predominantly white, predominantly middle-class, predominantly young and healthy. Women were underrepresented. People of color were largely absent. The poor, the elderly, and the chronically ill were excluded as confounding variables.

This was not unusual for the era. It reflected the standard practice of 19th and early 20th century medicine, which treated the white male body as the universal human template and everyone else as a deviation from the norm.

The blood pressure thresholds that became clinical standards in the 20th century were not initially derived from clinical trials. They were derived from life insurance actuarial data.

In the 1920s and 1930s, major American life insurance companies — including Metropolitan Life and Prudential — began collecting blood pressure data from their policyholders to assess mortality risk. These datasets were enormous by the standards of the time, and they became the foundation for the first widely accepted blood pressure norms.

The problem: life insurance policyholders in the 1920s and 1930s were not a representative sample of the American population. They were overwhelmingly white. They were disproportionately middle and upper class. Black Americans were systematically excluded from life insurance coverage by most major insurers during this period — a direct consequence of the racial segregation of American financial institutions.

The 1959 Build and Blood Pressure Study, published by the Society of Actuaries and based on data from 26 life insurance companies, became one of the most influential documents in the history of blood pressure medicine. It shaped clinical guidelines for decades. Its sample: approximately 4.9 million insured Americans, the vast majority of whom were white.

The "normal" blood pressure range that emerged from this data — and that was codified into clinical practice — was a statistical description of a racially and economically homogeneous population. It was presented as universal. It was not.

The Framingham Heart Study, launched in 1948 in Framingham, Massachusetts, is one of the most cited studies in cardiovascular medicine. It identified the major risk factors for heart disease — including high blood pressure, high cholesterol, and smoking — and its findings have shaped clinical guidelines for over 70 years.

The original Framingham cohort consisted of 5,209 residents of Framingham, Massachusetts. The town was selected for its size, its stable population, and its accessibility to Boston-area researchers.

It was also overwhelmingly white. The original 1948 cohort was almost entirely white — a reflection of Framingham's demographics and the study's recruitment methods. Black Americans, Latino Americans, Indigenous Americans, and other communities of color were not meaningfully represented.

The Framingham Offspring Study, launched in 1971 to follow the children of the original cohort, maintained the same demographic limitations.

It was not until 1994 — 46 years after the original study began — that the Omni Cohort was added to include participants of color. By that point, the cardiovascular risk models derived from Framingham data had already been embedded in clinical guidelines, medical education, and electronic health record systems worldwide.

The blood pressure thresholds, the risk calculators, the treatment algorithms — all of them were built primarily on data from a white New England town. All of them were applied universally.

The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC) has issued a series of reports since 1977 that have defined the clinical standards for blood pressure diagnosis and treatment in the United States.

The JNC reports established the thresholds that most Americans still recognize:

• Normal: below 120/80 mmHg
• Elevated / Prehypertension: 120–129 systolic
• Stage 1 Hypertension: 130–139 / 80–89 mmHg
• Stage 2 Hypertension: 140/90 mmHg or higher

These thresholds were derived from meta-analyses of clinical trials. And those clinical trials had a consistent problem: they underrepresented Black, Latino, Indigenous, and low-income patients.

The 2017 ACC/AHA guidelines — the most recent major revision — lowered the threshold for hypertension from 140/90 to 130/80, effectively reclassifying approximately 31 million additional Americans as hypertensive. The data supporting this change came primarily from the SPRINT trial (Systolic Blood Pressure Intervention Trial), which enrolled a more diverse population than earlier studies — but still underrepresented Latino and Indigenous patients, and enrolled Black participants at rates that did not reflect their disproportionate burden of hypertension.

Here is the central paradox of blood pressure medicine and race: Black Americans have the highest rates of hypertension of any racial group in the United States — and yet the clinical standards used to diagnose and treat hypertension were built almost entirely without them.

The numbers are stark:

• 55% of Black adults have hypertension, compared to 43% of white adults, 36% of Hispanic adults, and 39% of Asian adults (CDC, 2023)
• Black Americans develop hypertension earlier in life than white Americans
• Black Americans are twice as likely to die from hypertension-related causes as white Americans
• Black Americans have higher rates of hypertension-related end-organ damage — including kidney disease, stroke, and heart failure — at every blood pressure level

This is not a biological inevitability. It is the product of structural racism — the chronic stress of living under systemic inequality, the higher rates of poverty and food insecurity, the residential segregation that concentrates environmental hazards in Black neighborhoods, the lack of access to preventive care, and the diagnostic and treatment disparities that allow hypertension to progress further before it is addressed.

And it is compounded by the fact that the clinical tools used to manage hypertension were not built with Black patients in mind.

Standard blood pressure cuffs were calibrated on the arm dimensions of the populations studied — predominantly white, predominantly male. Research has documented that cuff fit significantly affects measurement accuracy, and that standard cuff sizes may produce systematically inaccurate readings in patients with arm circumferences that differ from the calibration population.

A 2023 study published in JAMA Internal Medicine found that hidden hypertension — blood pressure that is normal in the clinic but elevated at home — was significantly more common in Black patients than white patients, in part due to measurement artifacts. The study estimated that standard clinical blood pressure measurement may underestimate true blood pressure in Black patients in some contexts, contributing to underdiagnosis and undertreated cardiovascular risk.

For decades, clinical guidelines recommended different first-line blood pressure medications for Black patients than for white patients — specifically recommending against ACE inhibitors as first-line therapy for Black patients, based on studies showing lower average efficacy in Black populations.

This recommendation was based on real data. But it was data from studies that did not adequately explore why the difference existed — whether it was genetic, environmental, socioeconomic, or related to the chronic physiological effects of racial stress. The recommendation was applied as a blanket rule, reducing the treatment options offered to Black patients without fully understanding the underlying mechanisms.

The recommendation has since been revised, but it illustrates how clinical guidelines built on incomplete data can encode racial assumptions into standard care.

The Pooled Cohort Equations — the standard tool used to calculate a patient's 10-year cardiovascular risk and determine whether they should receive statin therapy — were derived from six cohort studies. The studies included some Black participants, but the risk equations for Black patients were derived from smaller samples and have been shown to overestimate cardiovascular risk in Black patients in some analyses.

This matters because overestimated risk can lead to overtreatment — unnecessary medication with real side effects — while underestimated risk in other populations leads to undertreatment. Neither outcome is equitable care.

One of the most significant gaps in standard blood pressure medicine is its failure to account for the physiological effects of chronic racial stress.

Dr. Arline Geronimus, a public health researcher at the University of Michigan, developed the "weathering hypothesis" in the early 1990s to describe the accelerated biological aging that occurs in Black Americans as a result of the chronic stress of living under systemic racism. Weathering manifests in elevated allostatic load — the cumulative physiological wear from chronic stress — which includes elevated baseline blood pressure, dysregulated cortisol, and accelerated cardiovascular aging.

The weathering hypothesis has been supported by decades of subsequent research. It helps explain why Black Americans develop hypertension earlier, why the disparity persists across income and education levels, and why standard risk calculators — which do not account for the physiological effects of racism — systematically mischaracterize cardiovascular risk in Black patients.

Standard blood pressure guidelines do not account for weathering. They do not account for the fact that a 45-year-old Black woman who has spent her life navigating systemic racism may have a cardiovascular age that is physiologically older than her chronological age suggests. They measure the number on the cuff. They do not measure the life that produced it.

The exclusion from blood pressure research was not limited to Black Americans.

Indigenous and Alaska Native communities were almost entirely absent from the major cardiovascular cohort studies of the 20th century. The Strong Heart Study, launched in 1988, was the first large-scale cardiovascular study of American Indian populations — and it found cardiovascular disease rates and risk factor profiles that differed significantly from the white populations on which clinical guidelines had been built. Decades of clinical guidelines had been applied to Indigenous patients based on data that did not include them.

Latino Americans were similarly underrepresented. The Hispanic Community Health Study / Study of Latinos (HCHS/SOL), launched in 2006, was the first large-scale cardiovascular cohort study of Hispanic/Latino adults in the United States. It found significant heterogeneity within the Latino population — with cardiovascular risk profiles varying substantially by country of origin, acculturation, and socioeconomic status — that standard clinical guidelines, built on non-Latino white populations, could not capture.

Both communities face the additional barrier of language access in blood pressure management. Hypertension management requires consistent monitoring, medication adherence, and lifestyle modification — all of which are harder to achieve when patient education materials, provider communication, and health system navigation are conducted in a language the patient does not speak fluently.

There has been genuine progress in recognizing and beginning to address the racial gaps in cardiovascular research.

The SPRINT trial (2015) enrolled a more diverse population than earlier blood pressure trials, including approximately 30% Black participants. Its findings — which supported lowering the hypertension threshold to 130/80 — were more applicable to diverse populations than earlier guideline-defining studies.

The REGARDS study (Reasons for Geographic and Racial Differences in Stroke) has been tracking cardiovascular outcomes in Black and white Americans since 2003, specifically designed to understand racial disparities in stroke and cardiovascular disease.

The NIH Revitalization Act of 1993 required the inclusion of women and minorities in NIH-funded clinical research — a mandate that has gradually increased the diversity of cardiovascular research populations, though implementation has been uneven.

Despite these advances, the fundamental problem remains: the clinical standards that govern blood pressure diagnosis and treatment in the United States were built on a racially homogeneous foundation, and the corrections have been incremental and incomplete.

• Black Americans still develop hypertension at higher rates and earlier ages than white Americans, and the gap has not closed
• Latino and Indigenous patients remain underrepresented in cardiovascular research relative to their share of the population and their burden of disease
• The risk calculators used in clinical practice still perform less accurately for patients of color than for white patients
• The chronic stress of systemic racism — one of the most significant drivers of elevated blood pressure in communities of color — remains outside the scope of standard clinical guidelines
• Hypertension control rates remain lower in Black Americans than in white Americans, despite higher rates of diagnosis

The numbers on the cuff have not changed. The lives that produce those numbers — the stress, the environmental exposures, the barriers to care, the legacy of being excluded from the research that defined "normal" — have not changed either.

DaisyMe Foundation is committed to ensuring that the communities most harmed by cardiovascular disease have access to care that accounts for their full reality — not just the number on the cuff.

Our work includes:

Community blood pressure screening and education — free screenings in community settings, with culturally responsive education about what blood pressure numbers mean, what drives them, and what patients can do.

Navigation support for hypertension management — connecting patients with primary care providers, helping them understand their medications, and supporting the lifestyle and environmental changes that affect blood pressure.

Advocacy for research equity — supporting policies that require meaningful representation of Black, Latino, and Indigenous communities in cardiovascular research, and that account for the social determinants of cardiovascular health.

Provider education — partnering with healthcare institutions to ensure that providers understand the history of blood pressure medicine, the limitations of current guidelines for diverse populations, and the role of chronic stress and structural racism in cardiovascular health.

The number on the blood pressure cuff is not neutral. It is the product of a history — a history of who was studied and who was excluded, who was counted as a data point and who was treated as an afterthought.

That history has consequences. It has consequences for the Black woman whose hypertension is undertreated because the risk calculator underestimates her cardiovascular age. For the Indigenous man whose blood pressure management is guided by standards built on data that never included him. For the Latino patient who cannot navigate the healthcare system in her own language.

The standard was not built for them. And until it is rebuilt with them — with their bodies, their lives, their stresses, and their histories at the center — the diagnosis gap will persist.

DaisyMe Foundation believes that every patient deserves a standard of care built on their reality. We are working to make that a fact — not just a promise.

Learn more about DaisyMe Foundation's cardiovascular health equity work. Explore our programs or get involved today.