Health disparities and the social determinants of health
Health disparities reflect unequal opportunities to attain health as well as differences in access to treatment. Housing, education, income, public policy and racism shape those opportunities, and reducing disparities requires action beyond individual patients and clinicians.
Health equity
Health equity means that everyone has the opportunity to attain their full health potential without disadvantage caused by social position or other socially determined circumstances. Equality describes things being equal; equity focuses more precisely on those opportunities and disadvantages. Leading determinants of health lie outside healthcare.
Differences between neighbourhoods include hospital resources, school facilities, air pollution, housing conditions and the affordability of preventive goods such as sunscreen. Measures of equity can compare adherence to prescribed medical or exercise regimens, preventive screening, premature births, survival after cancer or myocardial infarction, and pollution at neighbourhood schools.
Access barriers can accumulate within one family. In an emergency physician’s account published in 2018, a 67-year-old Latino man with diabetes and hypertension returned two months after admission for stroke with blood pressure of 210/114; his family had not bought the two prescribed antihypertensives because they were unaffordable and had missed follow-up because of money owed to the doctor and a broken car. The physician estimated that 70–80% of patients in her practice struggled to obtain basic care.
Documented US disparities
A 2017 qualitative synthesis of 19 National Academy of Medicine white papers found persistent, worsening health disparities and an unsustainable healthcare-spending trajectory that threatened US fiscal capacity. The American Hospital Association and Association of American Medical Colleges identified reducing disparities as necessary for performance and community health as well as ethics and social justice.
US evidence reported by 2018 showed that African American babies were more than twice as likely as white babies to have low birth weight or die in their first year, whereas corresponding rates among mothers who had emigrated from Africa resembled those among white mothers. American Indian and Alaska Native life expectancy was 4.4 years below the all-races US figure, and black Americans had a twofold excess risk of premature mortality relative to white Americans over 1960–2009. African Americans had higher death rates than other groups for many, though not all, cancers, while Hispanic Americans had lower rates of female breast, colorectal, lung and prostate cancer but among the highest rates of infection-associated cervical, liver and stomach cancers. African American hypertension prevalence was among the world’s highest; Medicaid claims for 2006–2008 showed lower screening mammography among women from racial or ethnic minority groups than among white women.
In 2015, obesity was 1.4 times as likely among African Americans and 1.2 times as likely among Hispanic Americans as among non-Hispanic white Americans; about four in five African American women and 77% of Mexican American women were overweight or obese. Evidence available by 2018 also put obesity among American Indian children at twice the rate among white and Asian children.
Life-expectancy estimates for the highest and lowest income quintiles showed widening gaps between cohorts who reached age 50 in 1980 and 2010: among women born in 1930 and 1960, respectively, the gap grew from 3.9 to 13.6 years; among men, from 5.1 to 12.7 years. A 2016 comparison put the gap between the richest and poorest 1% of US men at 14.6 years. The prevalence of nearly every chronic condition, including stroke, heart disease and arthritis, increased as income declined.
County-level maps showed substantial US life-expectancy differences in 2014 and widening disparities over 1980–2014: many counties with shorter life expectancy worsened while those with longer life expectancy improved, although the pattern did not apply everywhere or to everyone. County life expectancy was also significantly correlated with county voting patterns. By 2018, US life expectancy had begun to decline, with opioid overdose and suicide accelerating adverse trends beyond general metabolic risk. From 1989 to 2014, mortality from drugs, alcohol and suicide among white Americans aged 50–54 rose sharply while corresponding rates in other high-income countries declined and then levelled off. White men in the region between Oklahoma and West Virginia were experiencing particularly rapid deterioration in health outcomes.
Social conditions and health
Social determinants include where people live, poverty, education, access to healthy food and clean air, public policy and racial discrimination. Social conditions are reflected in biological risk factors including lipids, physical activity, smoking, obesity, glucose levels and diabetes.
Environment
Neighbourhoods differ in school quality, food access, pollution, housing pests and access to appropriately trained clinicians. US environmental disparities documented by 2018 included the following.
| Condition | Finding |
|---|---|
| Residential segregation | African American residential segregation was associated with adverse birth outcomes, pollutant exposure, shorter life, chronic disease, homicide and other crime, and shaped healthcare access, use and quality at neighbourhood, system, provider and individual levels. |
| Rural facilities | Rural hospitals typically lacked intensive-care, skilled-nursing, psychiatric and rehabilitation units and had fewer clinicians, especially specialists such as neurologists, anaesthesiologists and psychiatrists. |
| Healthy food | After adjustment for individual and neighbourhood covariates, healthy-food availability was strongly related to hypertension rates; greater cumulative exposure to healthy-food indicators correlated with lower type 2 diabetes risk. |
| Fine particulate pollution | The estimated mortality effect of PM2.5 pollution among black people was three times the estimate for the population overall in a continental US analysis. |
| Cardiovascular effects of pollution | Air pollution can trigger heart attacks, stroke and irregular heart rhythms, particularly among people with relevant risk factors. |
| Proximity to highways | The proportion living within 150 metres of a major highway was 3.1% among non-Hispanic white people, 5.0% among Hispanic people and 5.4% among Asian and Pacific Islander people. |
| Hazard exposure | Bus garages and toxic-waste sites were placed near marginalised neighbourhoods; failures to prevent drinking-water lead exposure occurred in Flint in 2015–2016; workers of colour faced disproportionate occupational hazards. |
| Housing allergens | Mouse allergens, dust mites, cockroaches and their droppings can trigger disease. |
| Healthcare infrastructure | Predominantly black neighbourhoods had lower-quality facilities, fewer clinicians and clinicians with lower clinical and educational qualifications than other neighbourhoods. |
| Segregation across institutions | Historical legally enforced and contemporary de facto discrimination segregated marginalised groups into lower-quality neighbourhoods, schools and jobs. |
| Rural mortality | Rural residents were more likely than urban residents to die from heart disease, cancer, unintentional injury, chronic lower respiratory disease and stroke. |
PM2.5 measures small particles in the air and indicates air quality.
Education
Education can affect health through literacy and knowledge, employment and healthier working conditions, earnings and control of living conditions, social support, and a sense of attainment that may buffer stress. The National Academy of Medicine identified education level as the most powerful determinant of lifelong health prospects. Findings available by 2018 illustrate unequal educational conditions.
| Condition | Finding |
|---|---|
| School pollution | A 2017 study of 84,969 public schools found racial and ethnic minority children bore the greatest air-neurotoxicant exposure, which might unequally affect performance and future potential. |
| School completion and smoking | In 2009–2010, smoking prevalence was 46.4% among 12th-grade-aged young people who had dropped out, compared with 21.9% among those still in 12th grade. |
| Travel to school | Children aged 10–18 in areas with high crime and dense off-premise alcohol outlets reported fear of violence while travelling to school. |
| School buses | Children continued to encounter diesel-bus particulate pollution despite technologies capable of nearly eliminating it. |
Government policy
Government policy allocates resources, with reducing disparities competing against other priorities. Policy-related disparities documented by 2018 included the following.
| Condition | Finding |
|---|---|
| Physician access | Most studies found Medicaid patients had less access to outpatient physicians, specialists and clinicians perceived as more qualified. |
| Medicaid payment | Many states paid physicians poorly for treating Medicaid patients. |
| Prevention in safety-net services | Limited resources and high demand made it difficult for safety-net health centres to introduce prevention practices despite their role in equitable cancer prevention. |
| Tobacco control | Taxation, restrictions on risky behaviours and increased treatment access were important population-level measures; the federal tobacco excise tax was $1.01 per pack compared with about $3.15 across high-income countries. |
| Government trust | Disadvantaged and disenfranchised people might fear government as well as distrust it. |
Income and poverty
Income contributes to health disparities, but prejudice and ethnic interactions also act independently. Evidence reported by 2018 identified more than 1.4 million US households, including 2.8 million children, living on less than $2 per person per day; extreme poverty rose sharply from welfare reform in 1996 to 2011, particularly among those directly affected. In 2013, non-Hispanic white family wealth was ten times Hispanic family wealth and more than twelve times African American family wealth; geographical income segregation increased over 1980–2015.
Income affects access to technology, fresh produce, medical costs and information about risk factors and procedures; reduced economic mobility can perpetuate poverty across generations. Poor and middle-income households devote a greater share of income to healthcare, leaving less disposable income that could relieve stress. Other findings reported by 2018 included the following.
| Condition | Finding |
|---|---|
| Appointments for children | A nationwide audit found 76% of orthopaedic offices refused an appointment to a Medicaid-insured child with a fracture, compared with 18% for a privately insured child. |
| Prescription affordability | In 2014, 19% of non-elderly US adults with prescriptions could not afford to fill them. |
| Pay and promotion | US studies found marginalised racialised groups received lower pay for the same work and fewer promotions despite similar performance evaluations. |
| Infant feeding | Exclusively breastfed infants had significantly less tobacco-smoke and pet exposure, later introduction of solid food and higher social class. |
Structural racism and stress
Structural racism comprises mutually reinforcing inequities in housing, education, employment, earnings, benefits, credit, media, healthcare and criminal justice, which reinforce discriminatory beliefs and resource distribution and affect health risks. It also encompasses the interaction of institutions, culture, history, ideology and codified practices that perpetuate racial and ethnic inequity, including differing outcomes despite individual clinicians’ best efforts. Understanding it requires attention to historical events such as slavery and the Tuskegee study; income differences alone do not explain health disparities.
A 2017 study found Hispanic mothers more likely than non-Hispanic white mothers to deliver at hospitals with higher risk-adjusted severe maternal morbidity; a 2016 study found black mothers more likely than white mothers to deliver in hospitals with higher risk-standardised severe maternal morbidity, contributing to black–white disparities. Children of imprisoned fathers had higher rates of behavioural and mental-health problems, including depression and anxiety, asthma and obesity. Bias may also affect patients’ encounters with administrative and clerical staff on arrival for care.
A Las Vegas study found drivers in a high-income neighbourhood less likely to yield to an African American pedestrian than to a white pedestrian crossing the same half of the road. Everyday discrimination can also occur in employment, promotion, policing and healthcare. A New York City police deputy inspector was recorded instructing officers to frisk black males aged 14–20 or 21. Poverty, difficult working conditions, dangerous neighbourhoods, disenfranchisement and structural racism entail stress. Evidence available by 2018 linked discrimination with allostatic load, telomere length, cortisol dysregulation and inflammatory markers, and linked racism with obesity in African American women and elevated lipids in African American men and women. Research on stress and biological dysregulation was still somewhat preliminary, although potentially important for explaining disparities.
Individual responsibility and collective action
Patients should take partial ownership of disease management and work with providers, but individual responsibility cannot substitute for clean air and water, adequate nutrition, pest-free housing, good schools or freedom from chronic stressors. Individuals can undertake behaviours such as toothbrushing and exercise, yet personal or community effort cannot by itself overcome polluted environments, unaffordable food or inadequate schools. Reducing inequity also depends on community, state and federal policy.
Evidence on reducing disparities
Health disparities are not inevitable: access, care quality and community social, economic and environmental conditions can change. Effective interventions include work within medical education, health systems, community organisations and public policy.
In 2018, professional organisations were connecting clinical care with public health in several ways.
- The American Academy of Pediatrics called for population-based care and collaboration with public health.
- Cancer-prevention efforts called for clinicians to work with grocery stores, community gardens, nutritionists and school-lunch funders and preparers because prevention tends to cost less and spare patients disease.
- The American Academy of Family Physicians’ EveryONE Project developed partnerships with medical and nonmedical organisations, advocated health-equity policies and sought evidence-based practices addressing social determinants.
- Pediatricians advocated on gun violence, water safety, immigration, childhood obesity and Zika; California pediatricians participated in vaccination legislation in 2015, and others addressed food insecurity and family separation through media advocacy. Food insecurity affected as many as 25% of US children.
- The American College of Physicians supported health considerations in all policies, health-impact assessments in community planning, interprofessional communication and team-based care for people at risk from adverse social determinants.
Medical education and workforce
The American College of Physicians recommended in 2018 that social determinants and the individual, community and systemic issues underlying inequity be incorporated at every level of medical education. Medical schools and residencies were increasingly addressing population health and community needs. Minority physicians often served underserved urban and rural populations, more often chose primary care and helped patients feel comfortable; nonwhite physicians cared for disproportionate shares of minority and non-English-speaking patients, 53.5% and 70.4%, respectively. In 2014, practising physicians were 75% white, 12.8% Asian, 6.3% African American, 5.5% Hispanic and 0.5% American Indian or Alaska Native. An earlier workforce study calculated that parity with US population subgroups would require incoming medical classes to double African American and Hispanic numbers, triple American Indian numbers, reduce Asian numbers by two-fifths and reduce white numbers by two-thirds. Research available by 2018 had not established the most effective ways to recruit and retain professionals from all backgrounds.
In 2018, the Association of American Medical Colleges’ diversity programmes included a minority-faculty development seminar, a certificate programme for minority students seeking healthcare executive posts and a webcast on assessing medical-school culture and climate. A three-month elective at Albert Einstein College of Medicine, including role-play about disparities and social determinants, increased participating students’ knowledge and confidence.
Health systems and community clinics
Increasing screening alone may not improve long-term outcomes: a study of African American women found that greater breast cancer screening improved outcomes only where subsequent diagnosis and treatment were available. Community-clinic budget cuts can widen disparities. Clinics can draw on religious organisations, local leaders, food pantries, fair-housing advocates and neighbourhood-watch groups; community ownership through participation is widely considered important for sustained population-health improvement, and residents are often invited onto advisory committees.
Community health workers are front-line workers who often live where they serve; in 2018, distinctions between paid staff, volunteers and stipended community members remained fluid. In one controlled trial, home visits, telephone calls and group classes for Hispanic people with poorly controlled type 2 diabetes significantly improved fasting glucose and HbA1c. In underserved patients with stroke in the previous 90 days, home visits significantly improved glucose control but not blood pressure or other cardiovascular risk factors.
Community members and trusted settings
Community-selected lay workers may receive brief training focused on a local health issue. Navigators help people through complex care pathways. In the Patient Navigation Research Program, 10,521 people were screened and the 2,105 with positive breast, cervical, colorectal or prostate cancer screens were randomised to navigation or usual care; at one year, navigation improved follow-up adherence during months 4–12. Navigators also improved awareness of and participation in cardiac rehabilitation after myocardial infarction, hepatitis B vaccination among foreign-born Asians from endemic regions, and nutrition among Hispanic people.
Service providers and trusted community settings can support health education. Barbershops have historically provided African American men with a setting for frank discussion; a 2014 systematic review found barber-led interventions mainly addressed prostate cancer and hypertension through discussions, written material, blood-pressure checks and clinic referrals. Knowledge and healthy behaviour improved, but outcomes varied and were inconsistently documented; salon interventions for African American women had comparable findings. Churches often serve as health-education centres in underserved communities. By 2018, African Americans were disproportionately represented on transplant waiting lists but were reluctant to donate organs. In a trial in African American communities, trained church peer leaders were randomised to discuss and show a film about organ donation or healthy eating; donor registries showed higher registration the following year among those attending organ-donation discussions, with similar results from church discussions about trial participation.
Policy and neighbourhood interventions
Voter registration and participation among underserved populations can influence whether policies reflect their health needs. Children raised in more diverse neighbourhoods were more likely to attend college and earn more, and less likely to be single parents. Teaching control of dust mites, cockroaches and mice improved quality of life among children with asthma. Greening vacant lots, street lighting and better public transport may reduce assault and homicide; an economic assessment estimated $13–$15 in reduced firearm-violence costs for every dollar spent remediating abandoned buildings and vacant lots.
School-based primary care in New York City reduced absenteeism. The Healthy Environments and Response to Trauma in Schools programme teaches educators to use empathy rather than harsh punishment to guide traumatised children away from behavioural crises. Group cognitive behavioural therapy in schools reduced post-traumatic-stress and depression symptoms among immigrant children.
Coordinated policy and investment
In April 2018, American Heart Association leaders expected the cardiovascular goals of Healthy People 2020 to be missed because efforts had not adequately reached the highest-risk and underserved groups; they called for combined clinical, social, economic and educational action towards Healthy People 2030.
Health in All Policies incorporates health considerations across transportation, agriculture, land use, housing, public safety and education. The 2010 Patient Protection and Affordable Care Act included the strategy and established a National Prevention Council led by the Surgeon General.
In 2018, Accreditation Council for Continuing Medical Education commendation criteria included health behaviours, care and payer systems, disparities and patients’ economic, social and physical environments, with encouragement for patients, families, caregivers and care teams to learn together. Financial feasibility matters alongside commitment to social justice; incentives for payment systems to reduce disparities were an active area of research and practice in 2018. Recommended directions for equity research included gathering more data, extending interventions’ reach and moving beyond disease-focused approaches.
A US estimate for 2000 attributed approximately 245,000 deaths to low education, 176,000 to racial segregation, 133,000 to individual poverty, 119,000 to income inequality and 39,000 to area-level poverty. A review of 61 studies identified transport as a major healthcare-access barrier, particularly for low-income, uninsured and underinsured people; a Nashville planning analysis associated not owning a car with poor health. Across US states over 2000–2009, higher social-service spending relative to medical spending was associated with better health outcomes.