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Key concepts

Allostatic load

Causality debate

Education and health

Food choices

Fundamental causes of health disparities

Geography of opportunity

Health behavior and social position

Health disparities

Health impact assessment

Housing as health care

How social determinants shape health

The inequality of violent injury and death

Obesogenic environment

Race and health

Socioeconomic status (SES)

Allostatic load

What is it?

One of the great, unsolved mysteries in medicine is explaining why health and longevity tend to increase with socioeconomic status – even among those who are materially secure. There is no threshold at which the link between increasing SES and better average health comes to an end.

Access to health care and differences in health behavior, such as smoking and eating habits, only account for part of the link between socioeconomic status and health.

Allostatic load theory attempts to explain how psychological and social experiences “get under the skin” and give rise to disease. The basic idea is that repeated stressful experiences can build up over time, gradually wearing down the body’s regulatory systems, opening the door to the onset and progression of many different diseases.  Bruce McEwen and Teresa Seeman explain,

“For each system of the body, there are both short-term adaptive actions (allostasis) that are protective and long-term effects that can be damaging (allostatic load). For the cardiovascular system, a prominent example of allostasis is the role of catecholamines in promoting adaptation by adjusting heart rate and blood pressure to sleeping, waking, physical exertion. Yet, repeated surges of blood pressure in the face of job stress or the failure to shut off blood pressure surges efficiently accelerates atherosclerosis and synergizes with metabolic hormones to produce Type II diabetes, and this constitutes a type of allostatic load.”

Measures of allostatic load are supposed to reflect how well or poorly the cardiovascular, metabolic, nervous, hormonal and immune systems are functioning. Higher scores indicate greater vulnerability to illness.  Researchers have proposed different ways to score allostatic load. They combine the results of various tests: blood pressure, body mass index (or waist-hip radio), kidney function, blood sugar, cholesterol, C-reactive protein, and cortisol and other hormones that regulate the response to stress.

By combining multiple test results in one index, researchers are trying to capture the accumulated effect on all physiological systems, including feedback loops between those systems.

It’s possible that this approach might give researchers and public health officials a more immediate way to test the results of policies or programs designed to reduce health disparities. Because it may take years to see an impact on disease outcomes, some effective programs may appear to be ineffective if evaluated over too short a time horizon.

Evidence

People with higher allostatic load scores who have been tracked for years in observational studies are more likely to develop heart disease, experience cognitive and functional decline, and die prematurely.

Numerous studies have found that allostatic load builds up faster in people lower on the socioeoncomic ladder. Higher allostatic loads emerge as early as the first five years of life and persist throughout childhood, adulthood and older age. People living in disadvantaged neighborhoods have significantly more biological “wear and tear” as measured by allostatic load, above and beyond the effect of individuals’ income, education and race or ethnicity.

African Americans tend to have higher allostatic loads than white people, and higher poverty rates among blacks do not account for the difference. In fact, in one national analysis, high allostatic load scores were more prevalent among nonpoor blacks than among poor whites. The average score for blacks was roughly equal to the score for whites who were 10 years older.

Caveats

Current evidence does not provide definitive support for the proposed links between psychological and social stresses and dysregulation of biological systems. The field continues to debate which physiological measurements should be included in the allostatic load index. Some researchers question whether the indices used to score allostatic load are actually measuring the processes by which repeated stressful experiences shape health over the life course. In a recent study examining the elevated rate of poor birth outcomes among African American women, for example, allostatic load scores surprisingly did not correlate with preterm birth or low birth weight.

Further reading:

Causality debate

Research linking socioeconomic status and health is almost all observational, which means it shows correlation, not causation. So the research does not firmly establish that low income, lack of education or low social status cause poor health. Most often, the influences are likely to be reciprocal: social status affects health and health affects social status. Chronic illness, for instance, can hinder success in education, employment, and earnings.

Some authors assert that socioeconomic status is a proxy rather than a true cause of health inequalities, and emphasize behavioral risk factors that are under the control of individuals.

The debate is not merely academic. It’s still not clear, for instance to what extent investing in education or income transfers would improve population health. Attempts to use tax credits, income support, or school funding to improve health aren’t likely to work if income and education aren’t primary causes of the social gradient in health. If they are primary causes, solutions focused on individual behavior don’t stand much chance of success.

Further reading

Education and health 

Education may be the aspect of socioeconomic status offering society the most powerful way to improve population health. And numerous studies have revealed that Americans with fewer years of education are falling farther behind in almost every measure of health status. Education acts on several levels: 

  • Increases knowledge, problem-solving, and coping skills, thus helping people make better-informed health choices. (People with more education are quicker to adopt changes in health-related behaviors in response to new evidence.)

  • Improves chances of securing a job with healthy working conditions, better employment-based benefits and higher wages. The job security and higher income that tend to come with more education provide a buffer from chronic stress - a corrosive force that undermines health among lesser educated, lower income people.

  • Gives people a greater sense of personal control. Positive beliefs about personal control have a profound impact on how people approach life, make decisions about risky behavior, and cope with illness.

Since 1980, life expectancy has changed very little among the less-educated and virtually all gains in life expectancy occurred among highly educated groups. From 1990 to 2008, the disparity in life expectancy between the most and least educated increased from 7.7 years to 10.3 years for women, and from 13.4 years to 14.2 years for men, the journal Health Affairs reported in 2012. Adults with fewer than 12 years of education now have life expectancies not much better than those of the overall U.S. population in the 1950s. 

The links between education and health are complex and intertwined. For instance, while education creates opportunities for better health,  poor health can also undermine educational attainment. And living conditions – especially at birth and in early childhood – profoundly shape both health and education. That means that improving the deteriorating health of Americans with fewer years of education will most likely require policies that go beyond schooling to include early child care, housing, transportation, food security, unemployment, and economic development.  

Further reading:

Food choices

Income, education, neighborhood environment and other social forces shape and limit the food choices people make. 

For instance, studies consistently have found a socioeconomic gradient in food choices: at lower levels of socioeconomic status, the consumption of whole grains, lean meats, fish, low-fat dairy products, and fresh vegetables and fruit decreases while the consumption of fatty meats, refined grains, and added fats increases.

Cultural ways influence food preferences, such as the heavier meat consumption researchers have noted in low-income households. Investigators who interviewed nearly 100 low-income mothers in Minnesota found that ethnic traditions were influential, along with taste, meat’s versatility in meal preparation, and the importance of meat as a status symbol. Meat preferences also reveal how differing education plays a role. In recent years, Americans higher up on the ladder of education and income status have cut back on red meat consumption since it’s been tied to higher rates of cancer and other health risks. 

People living in lower income places also tend to be surrounded by less healthy offerings: fast food restaurants with “dollar” menus and corner stores selling snack foods rather than boutique green grocers and farmers’ markets selling fresh produce. Lower income neighborhoods also are subject to a heavier barrage of advertising  for unhealthy food and drink than wealthier neighborhoods.

Among people in lower income populations, price appears to be a significant driver of food choices. A recent meta-analysis by researchers at Brown University and the Harvard School of Public Health calculated that healthy eating costs about $1.50 more per day per adult than eating a low-quality diet ($550 more annually per person). That extra cost represents a 25 percent increase for a household that spends $6 per person on food each day, which is more than many low-income families spend. An earlier study found that the cost of substituting healthier foods can cost 35 to 40 percent of an American low-income family's food budget.

Energy-dense foods (made of processed grains, sugar, and fat) are typically the most affordable choices. Such fare also has a longer shelf-life, which is extra meaningful for people short on money and needing to minimize waste. Processed foods also cost less in terms of the time it takes to plan and prepare meals for those struggling to work long hours outside the home while handling childcare and housekeeping.

Some studies have shown that healthy food choices don’t necessarily have to increase household food spending. In a recent Canadian study, for example, researchers tracked 73 women who adopted a Mediterranean diet and found that it didn’t cost them more. But that study included mostly college educated women, all from households earning well above the poverty level. Studies including disadvantaged households (e.g. here and here) suggest that such families can often barely afford food, purchase most of their groceries at the lowest available prices, and would probably have to pay more to adopt healthier choices. 

Further reading:

Fundamental causes of health disparities

Health and longevity tend to decrease with poverty and social isolation. This link has persisted since at least the early 1800s, which is hard to explain given that the U.S. and other wealthy nations have practically eliminated all of the infectious diseases that seemed to account for the unequal burden of death in poor households and neighborhoods in earlier times. Inequalities in mortality have continued at more or less the same level. All that has changed are the major causes of death, which are now cancers and chronic disease of the heart and vascular system.

Social scientists Jo Phelan and Bruce Link were among the first to make the case that inequalities in health are unlikely to change unless policy makers address inequalities in income, education, and social status. Link and Phelan developed an influential theory that describes how social forces are the fundamental causes of health disparities.

A fundamental cause, according to these authors, involves access to resources people can use to avoid or minimize a broad range of health risks:

For example, a person with many resources can afford to live in a high-SES neighborhood where neighbors are also of high status and where, collectively, enormous clout is exerted to ensure that crime, noise, violence, pollution, traffic, and vermin are minimized, and that the best health-care facilities, parks, playgrounds, and food stores are located nearby. Once a person has used [socioeconomic status]-related resources to locate in an advantaged neighborhood, a host of health-enhancing circumstances comes along as a package deal. Similarly, a person who uses educational credentials to procure a high-status occupation inherits a package deal that is more likely to include excellent health benefits and less likely to involve dangerous conditions and toxic exposures. In these circumstances, the person benefits in numerous ways that do not depend on his or her own initiative or ability to personally construct a healthy situation; it is an “add on” benefit operative at the contextual level.

Resources also shape individual health behavior, that is, whether people “know about, have access to, can afford, and receive social support for their efforts to engage in health-enhancing or health-protective behaviors,” in the words of Phelan, Link and Parisa Tehranifar. When cancer screening tests were first invented, for example, people with more resources were the first to gain access. Even now, screening rates for cervical and breast cancer remain higher among those with more education and income.

Resources such as knowledge, money, power, prestige, and beneficial social connections can be used no matter the prevailing health risks or available protective steps at any point in history. And this, according to the theory, is how socioeconomic status continues to shape health status even as the major threats and ways to avoid them change dramatically over time.

Supporting evidence

The theory predicts that mortality should be more equal for diseases that medicine still can’t prevent or effectively treat, and numerous studies support this hypothesis. Cancer survival, for instance, is worse among disadvantaged minority groups and the poor, but the survival gaps shrink for the types of cancer that aren’t amenable to existing treatments, according to a study based on national cancer statistics.  

Another study found that the survival advantage of more-educated individuals increases in the case of diseases with more rapid progress in treatment technology. The authors used two measures of treatment progress: the number of approved drugs to treat a disease, and the rate of change in mortality from that disease.

Sociologists Karen Lutfey and Jeremy Freese identified a “massive multiplicity of mechanisms” by which socioeconomic status acts as a fundamental cause of inequality in health outcomes. Their influential 2005 study used ethnographic analysis to compare the experience of diabetes treatment in two contrasting clinics, one with mostly white, middle- and upper-class patients, the other serving mostly minority, working class and under-insured patients.

Implications

Thinking about fundamental causes leads to different policies for addressing health inequalities than the prevailing approaches based on individual risk factors. Medical providers and public health campaigns typically identify modifiable risk factors (e.g. smoking, high blood pressure, lack of exercise, poor diet) and target individuals with interventions that attempt to change those individual risk factors. Fundamental causes theory predicts that interventions that aim solely to change individual risk factors will tend to worsen social inequalities in health. And there is some evidence that this really happens.

Phelan and coauthors assert that:

• Efforts to change individual risk profiles should first identify factors that put people “at risk of risks,” for example, overcrowded and dangerous neighborhoods with failing public schools and limited access to affordable, wholesome food. The idea is to avoid ineffective public health campaigns aimed at changing behaviors that are powerfully influenced by conditions left untouched by the intervention.

• Policies that aren’t normally considered health interventions may be the most effective way to reduce health disparities if they reduce resource inequalities. This could include, for example, minimum wage and parenting leave laws, head-start programs, housing for homeless and low-income people, college-admission policies, regulation of lending practices, and so on.

Further reading:

Social Conditions as Fundamental Causes of Disease
Bruce G. Link, Jo Phelan, Journal of Health and Social Behavior (1995)

Toward Some Fundamentals of Fundamental Causality: Socioeconomic Status and Health in the Routine Clinic Visit for Diabetes
Karen Lutfey and Jeremy Freese, American Journal of Sociology (2005)

Technological Innovation and Inequality in Health
Sherry Glied & Adriana Lleras-Muney, Demography (2008)

Social Conditions as Fundamental Causes of Health Inequalities: Theory, Evidence, and Policy Implications
Jo C. Phelan, Bruce G. Link and Parisa Tehranifar, Journal of Health and Social Behavior (2010)

Geography of opportunity

In the 1960s, anthropologist Oscar Lewis asserted that residents of poor urban ghettos absorb a “culture of poverty” in their early socialization and carry it with them into adulthood. In the words of James Rosenbaum and co-authors, "The fatalism underlying the culture of poverty affects everything they do; in effect, culture is internal. Similarly, in the traditional psychological view, efficacy is an aspect of an individual’s personality, an early formed, relatively stable characteristic that is unlikely to change."

But researchers in more recent years have found evidence to the contrary. They have proposed a “geography of opportunity” model of health disparities based on findings that neighborhood environments profoundly shape people’s health, schooling, employment opportunities, and quality of life. While the culture of poverty model assumes that low-income individuals who acquire a low sense of efficacy will tend to be stuck with it, the geography of opportunity model suggests that moving from disadvantaged neighborhoods will enable people to regain a sense of efficacy.

Better neighborhoods create opportunities in many different ways:

  • Provide access to more jobs, greater variety of jobs, and closer jobs.

  • Avoid the stigma of a housing project address, which makes it harder to get a job, and harder to get credit, which increases the costs of debt.

  • Ability to get jobs and credit gives people opportunity to see themselves as capable of being financially independent.

  • Integration improves people’s efficacy, as they realize that they are able to interact with people from other backgrounds as peers and friends.

  • Provides information and access to ways of attaining goals, for example, through better public schools and enrichment programs.

  • Gaining confidence from being around peers confident in their ability to succeed.

Experimental tests

Chicago’s Gautreaux Program, ordered by a Supreme Court decision in 1976, permitted thousands of low-income blacks to live in middle-income white suburbs. Between 1976 and 1998, over 7,000 families participated, and more than half moved to suburbs.

Studies tracking participants found that moving to a new environment could drastically change a person’s outlook. In an example cited by Rosenbaum and colleagues, “Ms. P” equated the housing projects to prison and found freedom in the suburbs:

I think it was the richness in the atmosphere that the children realized … they no longer had to be in the projects; they no longer had to dodge bricks and things coming in the building where they lived. Here they could just sit out and enjoy themselves, and they did… Because it was like living in a prison, you know. And when you can’t go out whenever you like and play or whatever—I had to go out with my kids—it’s hard. But up here, it’s a lot different; it’s quieter, much quieter. I’m able to sleep at night.

Moving to the suburbs removed some people from bad influences that had limited their efficacy. “Ms. Q” reported that prior to her move, she was "hanging with the wrong crowd."

The young adults around her were partying into the early hours, sleeping late, watching television through the day, and some were involved with drugs. She found it diffiŽcult to avoid these activities if she was to interact with her neighbors. Having a job did not fiŽt into this life style. After moving to the suburbs, she reports, “Now I’m trying to work and better my life … I have a better house, but I can’t live off of this [Program] forever, so now I’m trying to strive and get going back to school and trying to work and just better myself." In her old neighborhood, Ms. Q felt constrained by poor role models, peer pressure and a lack of opportunity. Living in the suburbs gave her a new outlook; she began to realize that she could actively control her life: “I felt better about where I lived, and that made me want to try to do something with my life other than just sit back and be nervous and worried all the time.”

The federal Moving to Opportunity Program provided another test of the geography of opportunity, but produced some strikingly conflicting results. Moving out of impoverished neighborhoods resulted in some health gains for girls, for instance, but made things substantially worse for boys. 

The program enrolled about 4,600 families in public or project-based assisted housing in high-poverty areas of Baltimore, Boston, Chicago, Los Angeles, and New York from 1994 to 1998. Researchers randomly assigned families to three groups: Some received vouchers to move to low-poverty neighborhoods, some received traditional vouchers enabling them to move but with no geographic restriction, and some received no change in the level of assistance. Researchers compared health outcomes 10 to 15 years later.

Girls in the traditional voucher group had decreased rates of major depression and conduct disorder, and girls in the low-poverty voucher group had no statistical differences, compared with those in the control group. Boys in the low-poverty voucher group had substantially increased rates of major depression, posttraumatic stress disorder, and conduct disorder compared with those in the control group. And boys in the traditional voucher group had an increased rate of posttraumatic stress disorder, the authors reported in JAMA.

The program also found no consistent impacts on adult economic self-sufficiency or children’s educational achievement.

Critics of the Moving to Opportunity study note that those who left public housing often moved into segregated neighborhoods lacking job opportunities and good schools. Social conditions weren’t significantly better than the ones they left.

Further reading:

Does Moving Poor People Work?
Thomas B. Edsall, The New York Times, Sept. 2014

The Enduring Effect of Neighborhoods
Richard Florida, The Atlantic (2012)

Beyond Individual Neighborhoods: A Geography of Opportunity Perspective for Understanding Racial/Ethnic Health Disparities
Theresa L. Osypuk and Dolores Acevedo-Garcia, Health Place (2010)

Privileged Places: Race, Uneven Development and the Geography of Opportunity in Urban America
Gregory D. Squires and Charis E. Kubrin, Urban Studies (2005)

How Do Places Matter? The Geography of Opportunity, Self-efŽficacy and a Look Inside the Black Box of Residential Mobility
James E. Rosenbaum, Lisa Reynolds and Stefanie DeLuca, Housing Studies (2002)

Health behavior and social position

People whose socioeconomic status is low are more likely to act in ways that harm their health compared with those higher on the ladder of income and social stature. On average, they smoke more, exercise less, have poorer diets, and more often ignore health advice and fail to comply with treatment. As a group, they are even less likely to use seatbelts.

Researchers have proposed many theories to explain why this is so, and these involve more than the inability to pay for goods and services that promote health. (Cigarettes are expensive, after all.) Walking and many other forms of exercise don’t require money, and neither does clicking a seatbelt.

Investing less in health behavior may be a positive adaptation to socioeconomic deprivation, according to a theory inspired by evolutionary biology. In other words, it’s like deciding to spend little on car maintenance when you live in a neighborhood of rampant car theft. Living under threat of high mortality from outside causes may set a limit on how much energy it is worth to put into lowering mortality from internal causes.

Another explanation that’s recently drawn a lot of media attention is the idea that poverty overloads the capacity of the brain to make sound decisions, an idea elaborated in the book Scarcity: Why Having Too Little Means So Much.

It’s important to note that the social patterning of unhealthy behaviors is not the same in every country. In France, for example, people on the upper end of the social ladder are almost as likely to smoke, eat poorly and neglect physical activity as people farther down the ladder, a recent study found.

So far, there is no grand unified theory that accounts for all social, psychological and political forces that press on people on the lower rungs of the socioeconomic ladder. In an informative review, Fred C. Pampel, Patrick M. Krueger, and Justin T. Denney break down the evidence for and against nine major pathways by which socioeconomic status shapes health behavior:

1. Self-medicating response to stress: Smoking, overeating, and inactivity provide pleasure and relaxation that help regulate mood among the disadvantaged.  This “self-medicating” function makes these behaviors tough to give up.

2. Fatalism and discounting the future: Lower lifetime earnings and wealth give people less reason to invest in future longevity and more reason to focus on the present in making decisions about health behaviors. People in disadvantaged circumstances may believe they gain little in terms of longevity from healthy behavior and feel fatalistic about their ability to act in ways that extend their lives.

3. Latent traits: Some traits related to intelligence and self-control are set early in life and to some extent determine school and employment success as well as adult health behaviors. To what extent this happens remains a matter of huge debate.

4. Class distinctions: As with fashion, people adopt lifestyle habits at least partly to reinforce their social position. Class distinction is part of what motivates more educated and wealthy people to swear off cigarettes, adopt a Mediterranean diet and spend hours per week doing yoga and Pilates. Likewise, class distinction may also motivate people with less education and income to set themselves apart with behaviors such as smoking that have come to symbolize independence, toughness, and freedom from convention.

5. Lack of knowledge and access to information: People with limited education are less knowledgeable of the harms of unhealthy behavior. If they live in a disadvantaged neighborhood, they are likely to be exposed to more advertising that promotes tobacco, liquor and unhealthy food.

6. Education and efficacy: Schooling increases problem-solving skills, ability to process information, self-control and efficacy. These are useful tools for overcoming the inertia of inactivity, the discomfort of exercise, and the desire for tobacco, unhealthy foods and excess calories.

7.  Ability to pay: Adopting healthy behaviors does not always require money, but having money makes it easier to take steps such as buying nicotine patches to quit smoking, joining a health club, or eating fresh fruits, vegetables, and lean meats. In this way, disposable income can help overcome low education, efficacy, and agency.

8. Neighborhood opportunity: Communities shape opportunities to adopt and maintain healthy behaviors. Low-income neighborhoods have more than their share of fast-food restaurants, liquor stores, and places to buy cigarettes and have less than their share of large grocery stores with a wide selection of healthy fresh foods.

9. Social Support, cohesion, and peer influence: Networks of family members, relatives, friends, and neighbors can support healthy behavior, discourage unhealthy behavior, and share information on ways to change. Or they can do the reverse. Wealthier and more educated people tend to associate with other high-SES persons in networks that promote health. People with less education and living in poorer neighborhoods have networks that can promote unhealthy behavior.

Researchers have done little to systematically compare the relative impact of these interacting forces, Pampel and co-authors note. They say it’s crucial to understand the difference between having the motivation versus having the means for healthy behavior. The stress response, fatalism, class distinctions, and knowledge of risk emphasize how socioeconomic status alters the motivation for healthy behavior. Education, income, and neighborhood opportunity focus more on how socioeconomic status can limit the means for healthy behavior.

“The distinction between motives and means tends to blur at the edges, as strong motives increase efforts to find effective means, and possessing scant means tends to sap motivation to change,” they say. “However, motives and means are analytically distinct, and distinguishing among them may aid in the study of disparities in health behaviors.”

The research suggests that it takes more than self-motivation to overcome poverty and the social determinants of unhealthy behavior.

Further reading:

Health Behaviours, Socioeconomic Status, and Mortality: Further Analyses of the British Whitehall II and the French GAZEL Prospective Cohorts, by Silvia Stringhini and others, PLoS Medicine (2011)

Socioeconomic Disparities in Health Behaviors

Fred C. Pampel, Patrick M. Krueger, and Justin T. Denney, Annual Review of Sociology (2010)

Why Are There Social Gradients in Preventative Health Behavior? A Perspective from Behavioral Ecology, by Daniel Nettle, PLoS One (2010)

Health disparities

Prosperity and advances in public health and medicine have pushed average life expectancy steadily upward–but not for everyone in the United States.

In many corners of the country, women and men are dying younger than they did 20 years ago. From 1983 to 1999, life expectancy among U.S. women fell by more than a year in 180 counties, and among men in 11 counties. Babies born in some U.S. neighborhoods have an average life expectancy 25 years shorter than their peers in more affluent enclaves just a few miles away.

These are examples of health disparities: health differences that are avoidable, unnecessary and unjust. Health inequalities, a more or less synonymous term, is seeing more use among researchers and public health officials because it more explicitly raises the issue of justice.

Not all health differences are health disparities. For example, worse health among the aged compared with the young, and higher rates of arm injuries among professional tennis players than in the general population don’t qualify, Paula Braveman, M.D., M.P.H., explains in a recent article. A serious disease outbreak in an affluent community not seen in less affluent communities would deserve attention but for reasons other than relevance to health disparities, she writes. “None of these examples reflects what is at the heart of the concept of health disparities: concerns about social justice—that is, justice with respect to the treatment of more advantaged vs. less advantaged socioeconomic groups when it comes to health and health care.”

Health disparities present a difficult challenge for policy makers. Social scientists have amassed convincing evidence that the root of the problem is economic and social disadvantage, which make people more vulnerable to illness, disability, suffering, and premature death. That means that to ameliorate health disparities will require more than expanding access to health insurance and medical care. It will require new policies that more effectively reduce poverty, increase economic opportunity, and prevent discrimination in education, housing and jobs.

Further reading:

Health impact assessment

Elected leaders and policy makers have opportunities to make choices that – if they take health into account – could help ameliorate public health problems such as the obesity epidemic and the large and growing disparities in the burden of chronic disease.

Health impact assessment, or HIA, is a way to scrutinize the effects a government program or project may have on the health of a population. The systematic process is supposed to help policy makers avoid unintended harmful effects and take advantage of opportunities to promote health.

According to the The Health Impact Project, an initiative of the Robert Wood Johnson Foundation and The Pew Charitable Trusts, "HIA gives federal, tribal, state and local legislators, public agencies and other decision makers the information they need to advance smarter policies today to help build safe, thriving communities tomorrow."

The number of assessments has mushroomed from a few dozen in 2007 to more than 240 completed or in progress in 35 states, Washington, D.C., Puerto Rico, and at the federal level as of 2013, according to a recent Institute of Medicine report.

Examples:

After a health impact assessment in Alaska, the Bureau of Land Management in 2007 withdrew part of an oil and gas development lease that threatened the health of native populations, and the approved lease required new pollution monitoring and controls.

A health impact assessment helped resolve concerns about a proposed biomass energy project in Placer County, Calif., in 2012. The assessment found that the project would likely benefit community health in the Lake Tahoe Region through the removal of forest slash and reduction of wildfire fuels, the diversion of open pile burns to more emission efficient combustion and the diversification of energy sources.

Boston’s regional transit agency in 2013 held off imposing steep fare increases and service cuts after a health impact assessment concluded that it would lead to significant health and financial costs because of increased automobile use.

How they’re done:

Assessments generally follow a six-step process.

1. Screening: Decide whether a HIA is warranted and would be useful in the decision-making process.

2. Scoping: Choose which health impacts to evaluate, the methods for analysis, and a workplan for completing the assessment.

3. Assessment: Gather data and predict health impacts using qualitative and quantitative research methods.

4. Recommendations: Prioritize evidence-based proposals to mitigate negative health impacts and maximize positive health impacts.

5. Reporting: Communicate findings.

6. Monitoring: Evaluate the effects of the impact assessment on the decision-making process.

Challenges:

The Robert Wood Johnson Foundation recently analyzed 23 health impact assessments completed between 2005 and 2013. Most weren’t given enough time or money, the authors concluded. People doing the assessments struggled to find relevant, neighborhood-level data, and they found it tough to make headway in politically charged situations. In some cases, agencies moved ahead on project decisions without waiting for completion of the health impact assessment.

Further reading:

Housing as health care

People who are homeless face many health threats and are among the heaviest users of hospital services. Safe and affordable housing, some experts assert, is a necessary first step to care effectively for people with chronic mental health and substance abuse problems who live on the streets. And there is some evidence that this approach may, in some circumstances, even save taxpayers money (but probably not as much as is often claimed).

In an influential 2009 study in Seattle, researchers analyzed medical and law enforcement costs for 91 people given supportive housing and found that costs dropped to about half the level seen among 35 comparable homeless people on a waiting list. But note that this savings estimate doesn’t include the capital costs of building and refurbishing apartments. Raising capital is likely to be a tall hurdle for many communities and this issue often gets ignored in news reports about the promise of supportive housing.

News coverage sometimes overstates the potential cost savings. In a study of supportive housing in Chicago, the savings were statistically insignificant. In a five-city study, clients in supportive housing wound up costing more than a comparison group of people not given housing.

Some advocates assert that saving money is an unfair requirement for a medical intervention that effectively relieves suffering. The cost-effectiveness of medical interventions is customarily measured in terms of quality-adjusted life-years gained, not dollars saved.

Housing First, a model developed by New York-based Pathways to Housing and others, has occasionally provoked controversy because of its “harm reduction” approach. Tenants are not required to take part in rehab or abstain from drugs or alcohol to remain eligible.

Some outstanding questions include:

  • Can cities fund addiction treatment services and mental health treatment adequately to serve everyone in supportive housing who seeks help?

  • How will proposed supportive housing stand up to NIMBY opposition from neighbors?

  • How should housing agencies handle residents who continue to use illegal drugs? What if the residents who continue to drink or use drugs have children living with them?

  • How will service agencies decide who will qualify for supportive housing? The available housing units aren’t likely to accommodate more than a fraction of the people in need.

Further reading

How social determinants shape health

Education, income, and social status appear to shape health in a complex web of interactions. Habits such as smoking, inactivity, poor diet and substance abuse are more prevalent among people in disadvantaged social groups, and probably account for much of the health gap between people of different social classes.

But behavior is not just a matter of personal choices. People are buffeted by social, cultural, and economic forces that can strongly influence behavior. In some disadvantaged neighborhoods, for example, tobacco and liquor advertising is prominent, lack of safe or convenient parks discourages outdoor recreation and much of the affordable food offered for sale is unhealthy.

Educational opportunity and achievement are especially powerful influences. Adults without a high school diploma, for example, are three times more likely to smoke than college graduates. Lesser education correlates with many other unhealthy behaviors. Education acts in at least two ways: It equips people with knowledge and skills useful for prevention of disease, and it paves the way to secure employment, a decent income and higher social status.

The physical environment and social quality of neighborhoods are important variables. People in lower-income and minority neighborhoods are likely to face more environmental health risks, such as hazardous waste sites and air pollution from nearby factories and highways. Such neighborhoods may lack social cohesion, undermining residents’ sense of security and well-being. Living in a neighborhood with high unemployment, urban blight and crime imposes a burden of chronic stress.

Prolonged exposure to stress can trigger the release of hormones, such as cortisol and epinephrine, that undermine immunity, boost inflammation and increase vulnerability to conditions such as diabetes and heart disease. Stress during fetal development, from a mother’s poor diet or exposure to pollutants, for example, may set the stage for diseases decades later in life by altering metabolism or triggering lasting changes in the activity of genes. Some studies suggest that these “epigenetic” changes in gene expression can be passed on to children and influence the occurrence of disease in more than one generation.

Further reading

The inequality of violent injury and death

Injuries and violence kill more young people in the U.S. than any other cause of death. The burden of these deaths varies enormously by race, ethnicity and social class. Deaths by homicide, for instance, are more than nine times more prevalent among blacks than among non-Hispanic whites, and homicide deaths are three times more common among American Indians and Alaskan Natives than among non-Hispanic whites under age 30:


Age-adjusted suicide and homicide deaths per 100,000 by race and ethnic origin in the year 2011 among those ages 0 to 29 in 17 states tracked in the CDC’s Web-based Injury Statistics Query and Reporting System (WISQARS).


 

Life expectancy numbers show that the unequal burden is stark. Homicide takes two full years off the expected life span of black males in Los Angeles County and homicide subtracts nearly five years from the expected life span of black males in some low-income urban areas of Los Angeles.

The most dangerous counties in the United States have violent death rates that are more than 10 times higher than the safest counties.  As you can see in the map below, rates vary from less than 10 to more than 100 violent deaths per 100,000 population, based on homicides, police shootings, and suicides in the years 2004 through 2010. (Counties with rates based on 20 or fewer deaths are unreliable and are marked as suppressed.)

Source: WISQARS



Root causes

Credible evidence supports claims that the excess deaths are partly a consequence of the kind of society we have built, a society that marginalizes certain classes of people, depriving them of high-quality education, job opportunities, and healthy neighborhood living conditions. A Lancet paper, written by researchers from the Centers for Disease Control and Prevention, explains:  

Young people growing up in communities with concentrated disadvantage are more likely to witness violence, attend underperforming schools, and have poor employment opportunities; they are also more likely to be exposed to drug-distribution networks and can access firearms more readily than can young people not growing up in such communities. These social and environmental factors can greatly increase an individual's risk of perpetrating violence and being a victim of violence. Thus, the link between socioeconomic status and injury is mediated by many conditions at home, at work, in communities, and within families and groups, with variations in effects noted across different types of injury. Social and economic factors fuel stress; challenge adaptation and coping mechanisms; contribute to social exclusion and isolation, residential instability, workplace pressures, and low community participation; and affect access to safe environments, safety equipment, and services. These factors can accumulate and interact to substantially affect experiences and risks.

Some research suggests that neighborhood environment largely explains the racial and socioeconomic differences in death rates. A study of homicide risk in Atlanta in the 1970s, for instance, found no differences in homicide by race when household crowding was used as a measure of neighborhood socioeconomic conditions. In a Los Angeles study published in 2010, 75 percent of the neighborhood variation in homicide’s impact on life expectancy could be predicted from neighborhood poverty levels.

Higher socioeconomic status may not protect the health of people who are well off when they live in poor environments. Regardless of your socioeconomic status, you are more likely to die of an injury if you live in an area with high poverty levels. The study that reached that conclusion found no link between individual social position and suicide, but a 50 percent increased risk of suicide for people living in neighborhoods with low socioeconomic status, high concentration of racial groups, and high residential and family instability.

Note how the risk of violent injury (and other injuries) rose with each step of decreasing neighborhood socioeconomic status in a ten-year study of hospitalizations in Memphis, Tenn., and surrounding Shelby County:

Source: A Population-Based Analysis of Neighborhood Socioeconomic Status and Injury Admission Rates and In-Hospital Mortality, by Ben L. Zarzaur and others, J Am Coll Surg (2010)


 

Policy solutions

Some authorities say it might be best to target prevention efforts (e.g. public awareness campaigns, community policing, increased police patrols, collaborative involvement of neighborhood associations and local businesses) on high-risk neighborhoods, rather than diluting limited resources over a broader population or geographic area.

Others say that the U.S. needs to do more to confront the root causes of the inequality with strategies that reduce bias and discrimination and improve access to employment, safe housing, and high-quality education.

Cities such as Baltimore have tried to reduce the density of bars and liquor stores in high-crime neighborhoods because the density of alcohol outlets has been linked to higher rates of violent crime. The so-called Broken Windows theory has led to initiatives that try to reduce violence by restoring deteriorating neighborhoods, removing or securely sealing abandoned buildings, and greening vacant lots. The idea is that abandoned places give cover to criminal activity and signal that no one is in control.

Researchers in Philadelphia found a significant association between the risk of violent assault and the presence of abandoned buildings and vacant lots, even after controlling for demographic and socioeconomic characteristics of the neighborhoods. Vacant properties also had the strongest effect size, prevailing over almost a dozen well-known indicators of disadvantage. The following figure shows the link between rates of violent assault and the number of vacant properties across every census block group in Philadelphia County between 2002 and 2006:


Source: Vacant Properties and Violence in Neighborhoods by Charles C. Branas & others, ISRN Public Health (2013)


 

The same group of investigators conducted a decade-long study of the impact of a vacant lot greening program in Philadelphia by comparing vacant lots that were converted into parks with matching lots that were left abandoned. They found that vacant lot greening was linked with consistent reductions in gun assaults. The impact on other types of crimes was less clear, however, and a smaller but more controlled trial found less evidence of an effect.

Obesogenic environment

Some of the social changes we’ve allowed – or even embraced – make it difficult for people to avoid unhealthy weight gain in the U.S. One of the most vivid demonstrations of our obesogenic environment is what happens among successive generations of immigrants: one recent study of Mexican immigrants found that the risk of becoming obese tripled by the second generation, relative to peers who remained in their native land.

Relative odds of obesity for women migrating from Mexico to the U.S. (Source: Mexico–United States Migration and the Prevalence of Obesity: A Transnational Perspective, Karen R. Flórezet al, JAMA Internal Medicine 2012)

Here are some of the environmental factors behind the rapid rise of obesity in the U.S. since the 1980s:

Food production & marketing
Food companies spend over a billion dollars a year marketing nutrient-poor, calorie-dense convenience meals and snacks to children, producing measurable changes in food preferences and eating habits. U.S. Farm subsidies have boosted the output of nutrient poor, energy-dense food and pushed down the prices relative to healthier options. From 1985 to 2000, retail prices of fresh vegetables and fruit rose nearly 120 percent, about six times more than the rate of increase for soft drinks and three times more than that of sweets and fats.

Child development
Obesity is the outcome of a process that can start in fetal development and infancy. An expectant mother’s severe undernourishment, or substantial
overnourishment, can alter fetal metabolism and brain development, making offspring more prone to obesity, according to a number of animal and human studies. During infant development, observational studies have linked bottle-feeding rather than breast-feeding to weight gain. Lack of sleep, a trend affecting even toddlers, appears to promote obesity by disturbing the regulation of the hormones that drive appetite and the body's rate of energy use. In the Early Childhood Longitudinal Study, which tracked 7,738 kindergartners for a decade starting in 1998, half of the cases of obesity that arose were among kids who had become overweight during the preschool years.

Built environment
Unsafe streets and lack of green space may be barriers to being physically active, although the
evidence is limited. The effects of income and education may trump the influence of the built environment. It is clear that a lack of physical activity is one of the key factors in the worsening obesity gap between haves and have-nots. Children of college-educated parents have became more active than they were a decade ago, while children of less educated parents showed no improvement, according to a recent analysis.

Access to healthy food
People living in lower income neighborhoods tend to be surrounded by less healthy offerings, i.e., fast food restaurants and corner stores selling convenience foods rather than green grocers and farmers’ markets selling fresh produce. Lower income neighborhoods may also be subject to a heavier barrage of advertising for unhealthy food and drink than higher income neighborhoods. To what extent “food deserts” drive obesity remains unclear. But the high price of healthy food does appear to be a significant driver of
fattening food choices among families with limited incomes.

Further reading:

Race and health

Life expectancy and mortality data reveal a complexity in the way race, ethnicity and gender combine to affect health risks. Compared to white Americans, African Americans and American Indians have higher death rates at every age from birth until advanced age. But black women have higher levels of life expectancy than white men at every age. Hispanics in the U.S. have lower mortality than whites at older ages. And Asians have lower mortality rates throughout life. 

Racial disparities in health have persisted for decades – and in some cases worsened. Infant mortality for African Americans was 1.7 higher than for whites  1940, and despite steep reductions in infant deaths, the gap between blacks and whites has widened such that the rate among blacks was 2.4 times higher than whites as of 2006. In 1950, black and white Americans had comparable death rates for heart disease and cancer, but now death rates for both diseases are significantly higher among blacks.

Socioeconomic status
Blacks and Hispanics have levels of overall poverty that are two to three times higher than those of whites. And socioeconomic inequalities have changed little over time, contrary to perception.  But even after taking socioeconomic status into account, many disparities in health remain. A study comparing white physicians from Johns Hopkins University with black physicians from Meharry Medical College found large racial differences in health. Diabetes and hypertension were twice as high among the black doctors, who also had higher rates of heart disease than the white doctors.

“Weathering hypothesis”
One cause of ethnic and racial disparities could be greater exposure to adverse social conditions and physical environments, which leads to greater wear and tear on physiological systems. Comparisons of infant death rates supply intriguing evidence to support this so-called “weathering hypothesis.” Among white and Mexican American women, infant mortality rates are lower for mothers who give birth in their twenties compared to those in their teens. But it’s the opposite for African American and Puerto Rican women in the U.S., who experience the lowest infant mortality as teenagers and higher infant mortality in their twenties,  perhaps as a result of accumulated stress. 

A revealing study compared African Americans and whites on measure called “allostatic load,” which is supposed to reflect how well or poorly the cardiovascular, metabolic, nervous, hormonal and immune systems are functioning. Scores are based on readings of blood pressure, body mass index, kidney function, blood sugar, cholesterol,  C-reactive protein and other tests. The study found that blacks scored worse than whites at all ages, and the racial differences persisted after adjustment for poverty. In fact, nonpoor blacks scored worse than poor whites.

Racism
Recent studies have found links between discrimination and health outcomes including sleep disturbance, abdominal fat, high blood sugar, coronary artery calcification, and breast cancer. Acceptance of negative stereotyping by stigmatized groups can be a source of anxieties that undermine social and psychological functioning. This so-called “internalized racism” has been linked to excessive drinking and psychological distress among African Americans. But as it stands, only a few studies have attempted to pin down the role of discrimination as a cause of health disparities.

Medical care
Blacks in the United States are two to three times more likely than whites to have diabetes-related amputations, but blacks living in the U.K. face no higher risk than whites. Some experts believe that the near universal access to primary care in the U.K. accounts for the difference.  There is evidence suggesting that prevention-oriented health care can help reduce disparities in health.

Costa Rica is an eye-opening case study. The country’s infant death rates fell from 60 per 1,000 live births in 1970 to 19 per 1,000 live births in 1985. Researchers attribute most of the improvement to public health programs, particularly the build up of primary health care in underserved areas in the 1970s. For each five years after primary care reform, child mortality fell by 13 percent, and adult mortality fell by 4 percent.

Experts in the field of social determinants of health tend to minimize the importance of medical care. (One widely quoted estimate asserts that medical care account for just 10 percent of potentially avoidable deaths.) But some research indicates that medical care may achieve bigger positive changes among socially disadvantaged populations than among the well-off.

Further reading:

 

Socioeconomic status (SES)

Health studies routinely attempt to account for socioeconomic status, which is a person’s place in the hierarchy of wealth, self-determination, prestige and power. Socioeconomic status, or SES, is strongly linked to health and longevity. People higher on the SES ladder tend to live longer and healthier lives than people lower on the ladder. This link, the SES-health gradient, persists even among people in the middle and upper ranges of social position, many studies have shown.

To account for socioeconomic status, researchers typically rely on proxy measures such as years of education or household income. It’s convenient to do so, and sometimes no better data is available.

However, it’s important to keep in mind that proxy measures can obscure substantial socioeconomic differences.

Studies that compare people by househould income, for instance, are blind to potentially very large differences in wealth. Wealth, or total accumulated economic resources, is a stabilizing force that buffers families from the effects of setbacks such as unemployment or illness. People with comparable income can have drastically different wealth. Among very low income households, those headed by whites have about 400 times as much wealth as those headed by blacks. At higher income, whites have about 3 to 9 times the wealth of blacks.

Using years of education as a proxy can overlook meaningful differences in the quality of education. In some disadvantaged neighborhoods and cities, the quality of public schools is drastically worse than average. Also, years of education is definitely not a reliable stand-in for income or wealth. In the U.S., for example, black adults with 12 years of schooling earn 33 percent less, on average, than white adults with the same level of education, while Mexican-Americans earn 18 percent less than whites. Racial and ethnic disparities in income persist at every level of educational attainment, possbily as a result of unequal employment opportunities and differences in educational quality.

One-time measures of socioeconomic status ignore the effect of past experiences. Socioeconomic status can change over the course of a life, and past episodes of poverty or dramatic loss of income can have long-lasting effects on health. Deprivation during fetal development and early childhood, for example, can increase vulnerabilty to disease decades later.

Focusing on proxy measures of individuals may fail to register the influence of the different neighborhoods where people live.  The characteristics of the built environment and social fabric of a neighborhood are powerful enough to shape health above and beyond the individual’s socioeconomic status.

In an informative review article worth reading in its entirety, Dr. Paula Braveman and colleagues distilled some useful conclusions about difficulties of accounting for socioeconomic status:  

• Proxy measures of socioeconomic status are not interchangeable.  

• Proxy measures can miss important and relevant aspects of socioeconomic status, and even studies that include multiple measures cannot capture all of the potentially important socioeconomic influences on health.

• A given proxy measure may have different meanings depending on the race, ethnicity, age, sex, or neighborhood environment of the people being considered.

• Racial and ethnic health disparities are likely to reflect unmeasured socioeconomic differences. (But that doesn’t mean that racial and ethnic disparities are reducible to socioeconomic issues; discrimination may also be an active force.)

Further reading:


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