This week I
developed hypertension, not because my blood pressure increased but because new
guidelines lowered the threshold for defining what is abnormal. In the US,
this has doubled the number of hypertensive women under the age of 45, tripled
the number of hypertensive men under 45, and increased the overall rate of high
blood pressure from a third to nearly half—and more than half for African
Americans.
But will expanding the definition of
hypertension, while keeping its prevention restricted to medications and individual
“lifestyle changes,” help mass prevention?
Silent killer
Cardiovascular
disease is the leading causes of death but is also preventable because it tends
to develop after people have been exposed to risk factors for years. One of the
main biological risk factors, high blood pressure, has been called the “silent
killer” because people don’t experience any symptoms for years until they
suffer a heart attack or stroke. The concern that our bodies are ticking time
bombs frequently leads people to go the emergency department in the absence of
any symptoms, just because their blood pressure reading is high. But as the
saying goes, “treat the patient, not the number.” In the vast majority of
cases, hypertension—in the absence of symptoms or signs of organ damage—is not
an acute medical problem requiring immediate treatment, but a chronic risk
factor requiring prevention.
For decades
we’ve known that the risk of cardiovascular disease increases as blood pressure
rises, and that normalizing blood pressure can lower the risk. But trying to
prevent cardiovascular disease in a population by treating “high risk”
individuals, without addressing what determines the population risk as a whole,
runs into the problem inherent in this approach. As epidemiologist Geoffrey
Rose explained in his article Strategy of prevention:
lessons from cardiovascular disease,
“The
preventive strategy that concentrates on high-risk individuals may be
appropriate for those individuals…but its ability to reduce the burden of
disease in the whole community tends to be disappointingly small. Potentially
far more effective, and ultimately the only acceptable answer, is the mass
strategy, whose aim is to shift the whole population’s distribution of the risk
variable.”
But rather than
expanding the approach to cardiovascular disease prevention in order to shift
the whole population distribution of risk, guidelines have focused instead on
expanding the definition of high blood pressure—labeling more people as “high
risk” and in need of treatment.
Medicalizing prevention
Whereas
hypertension was previously defined as 140/90 (“normal” being 120/80), the 2003 guidelines created
the concept of “pre-hypertension”: blood pressure at the upper end of normal
(120-139/80-89), which was at risk of becoming high blood pressure. In other
words, “pre-hypertension” was a risk factor for a risk factor for a disease. While
broadening the concept of risk, treatment remained the same: individual “lifestyle
choices” like diet and exercise.
At the same time
studies have found that intensive blood pressure lowering can reduce mortality
rates in high-risk groups. Much of the discussion of the new guidelines quotes
the 2015 SPRINT
trial that reduced mortality by lowering blood pressure to 120. But this
was in a selected group of patients with previous heart or kidney disease or
other high risks, and the small absolute mortality reduction came at the cost
of more emergency department visits for low blood pressure and kidney injury. Now
this cost-benefit decision in a high-risk group of patients has been
generalized to everyone—which will be eagerly received by pharmaceutical and
insurance companies. In the same year as the SPRINT trial, the Journal of
Insurance Medicine found that “switching to a ‘normal’ reference range of
SBP<130 offers superior risk assessment relative to using BP<140/90.” In
the latest blood pressure guidelines, “high blood pressure” has been lowered
from 140/90 to 130/80, “pre-hypertension” has disappeared, and 30 million
Americans have been labeled with a pre-existing condition. If this results in high premiums or reduction in health care coverage, the expansion of diagnosis in the interest of promoting health could could reduce
access to healthcare or force more people to chose between medicine and food.
My blood
pressure has consistently been in the 130s over 80s—and yet I’ve gone from
having normal blood pressure, to having “pre-hypertension” and now having high
blood pressure. But isn’t this extra vigilance needed if cardiovascular disease
(CVD) continues to be the leading cause of death? As the guidelines state,
“hypertension accounted for more CVD deaths than any other modifiable CVD risk
factor and was second only to cigarette smoking as a preventable cause of death
for any reason.” But the only risk factors considered modifiable are individual
diet, exercise, and smoking/alcohol.
The definition
of blood pressure has expanded, but the approach to prevention has not. As the
former past president of the American College of Cardiology explained “an
important cornerstone of these new guidelines is a strong emphasis on lifestyle
changes as the first line therapy. There is an opportunity to reduce risk
without necessarily imposing medications.” But as the guideline co-author explained,
"Yes, we will label more people hypertensive
and give more medication, but we will save lives and money by preventing more
strokes, cardiovascular events, and kidney failure."
In other words,
the only option we have to prevent cardiovascular disease on a population level
is to label more people as at risk, and focus control on individual consumption
and medicating our internal environment. There must not be any other
modifiable risk factor, and nothing else we can do to stop the ticking time
bomb. The “comprehensive” 500-page guideline has one paragraph on
“environmental risk factor,” which it redefines as diet, physical activity and
alcohol consumption. Factors in our external environment—including those that
restrict consumption choices and access to medicine—must be irrelevant.
Embodying our world
But
hypertension, cardiovascular disease, and every other health issue are not
disembodied phenomena, arising spontaneously irrespective of
context. As social epidemiologist Nancy Krieger explains, “we,
like any living organism, literally incorporate, biologically, the world in
which we live, including our societal and ecological circumstances…The concrete
reality of embodiment in turn is expressed in biological characteristics, which
exhibit both individual and population distributions.” Hypertension and its complications are not a
purely biological phenomena but are intertwined with a number of social, economic
and ecological silent killers.
According to
last year’s World Health Organization report, Preventing
disease through healthy environments: a global assessment of the burden of
disease from environmental risks, a quarter of all global deaths are due to
environmental factors. Modifiable factors such as air pollution, road traffic,
occupational exposures, and high demand and low control work contribute to 35% of
the total burden of ischemic heart disease and 42% of the total burden of
stroke. Looking only at pollution as a cause of illness, this year’s Lancet
commission on pollution and health found that “in 2015, all forms of
pollution combined were responsible for 21% of all deaths from cardiovascular
disease, 26% of deaths due to ischaemic heart disease, 23% of deaths due to
stroke”. As it details, pollution influences every aspect of cardiovascular
disease—from risk factors like high blood pressure, serum cholesterol and
insulin resistance, to the development of atherosclerosis, to emergency
department visits and mortality. Surely this should be included in a comprehensive
assessment of how to prevent cardiovascular disease.
The disproportionate distribution of environmental
pollution, precarious work and stress also help explain the disproportionate
rates of high blood pressure in the Black community. Differential rates have
been noticed for years but are often reduced to claims of racial difference.
The Management of High
Blood Pressure in Blacks guideline explains high rates of blood pressure by
blaming cognitive factors like “nonbiomedical beliefs,” behavioural factors
like less physical activity and bad diets, and physiological factors like different kidney function and salt retention. This focus on inherent biological
difference has a long history. As White Coats for
Black Lives explains, “biomedical research has historically characterized
the very bodies of Black people as being the center of countless diseases,
without thinking critically about how socioeconomic disparities and historical
institutional discrimination have lead to the disproportionate amounts of
disease observed in minority populations.”
Differential
rates of blood pressure and other risk factors are not an indicator of inherent biological
difference, but are embodied expressions of the totality of social, economic,
and ecologic inequalities—which also constrain “lifestyle choices” and access
to medicine. The result is higher rates of cardiovascular disease: the embodied experience of racism is literally heart breaking. As Krieger explained:
“Considering the public health problem of
increased risk of hypertension in African Americans compared with white
Americans, ‘embodiment’ reminds us that a person is not one day African
American, another day born low birth weight, another day raised in a home
bearing remnants of lead paint, another day subjected to racial discrimination
at work (and in a job that does not provide health insurance), and still
another day living in a racially segregated neighborhood without a supermarket
but with many fast food restaurants. The body does not neatly partition these experiences—all
of which may serve to increase risk of uncontrolled hypertension, and some of
which may likewise lead to comorbidity, for example diabetes, thereby further
worsening health status.”
In a study 20
years ago, she found that anti-Black racism and internalized oppression is a
significant risk factor for hypertension: “the blood pressure differences we
observed associated with reported experiences of racial discrimination, in
conjunction with response to unfair treatment, are on par with or exceed those
associated with other cardiovascular risk factors targeted for nonpharmacologic
interventions (eg lack of exercise, smoking, and unhealthy high-fat, high-salt
diets).”
This does not
mean dismissing the power of medicine and the potential of individual choice,
but empowering access to healthcare and individual agency by challenging their
constraints. If we expand the definition of high blood pressure we should also expand the understanding of its broader causes, and if we lower the threshold for medical intervention we should also lower the threshold for social, economic and ecological improvement. As Rose explained in his book Strategy
of Preventive Medicine,
“A
population-wide approach can itself operate at either a more superficial or a
more basic level. Health education is often only a superficial approach, when
it seeks simply to encourage or persuade people to behave differently. A
radical approach aims to remove the underlying impediments to healthier
behavior, or to control the adverse pressures. The first or medical approach is
important, but only the social and political approach confronts the root
causes.”
Thankfully there
are movements confronting anti-Black racism, climate injustice and precarious
work—which can combine with healthcare to both treat the biological expression
of high blood pressure and address the social, economic and ecological causes
it embodies.