Comprehensive Notes on Population Health, Life Expectancy, and Social Determinants of Health

Purpose of Epidemiological Studies and Population Health Indicators

• Epidemiological studies aim to improve human health by investigating the causes of health issues and applying findings to population interventions.
• Core population health metrics include:
  • Morbidity: The prevalence or incidence of sickness or disease within a studied population (e.g., a scenario where $30\%$ of a population contracts an illness).
  • Mortality: Death rates within a population, focusing on whether mortality is disproportionately higher in specific subgroup populations.

Concepts of Life Expectancy

• Life Expectancy: A statistical estimate of the average number of years a person is expected to live.
• Healthy Life Expectancy: The predicted number of years a person is expected to live in a healthy state.
  • Defining "health" involves variable criteria, making healthy life expectancy a complex metric to measure precisely.
  • The goal of public health is to increase both overall life expectancy and healthy life expectancy, closing the gap between the two metrics.
• United States Life Expectancy Statistics:
  • Overall US life expectancy is $77.8\,\text{years}$.
  • Women in the US have an average life expectancy more than $5\,\text{years}$ higher than men.
  • For healthy life expectancy, the gender gap narrows, but overall healthy life expectancy is significantly lower than total life expectancy.
  • The average American lives the last approximately $12\,\text{years}$ of life in an unhealthy state.
  • In $2019$ (prior to the COVID-19 pandemic), overall average US life expectancy decreased for the first time in a long period, signaling a major public health red flag.
  • In $2021$, average US life expectancy was $76.1\,\text{years}$, meaning individuals who died in $2021$ died at an average age of $76\,\text{years}$.

Gender Disparities in Mortality and Health Outcomes

• Women outlive men across $37$ comparable countries and globally throughout recorded history.
• Men are more likely than women to die from almost every major cause of death across nearly all age cohorts.
• Avoidable Mortality in Men:
  • The US has the highest rate of avoidable deaths among men (defined as deaths occurring before age $75$) compared to any peer nation.
  • Rate of avoidable male deaths in the US: $337$ deaths per $100\,000$ men.
  • This rate is over $100$ deaths per $100\,000$ higher than the United Kingdom (the country with the second highest rate) and more than double the rate of Swiss men.
• Demographic and Economic Implications:
  • Rapid population aging is occurring in the US and globally.
  • Because women live longer but historically experience lower earnings and patchier career trajectories, they face unique economic challenges supporting longer retirement periods.
• Causes of Earlier Male Mortality:
  • Biological Factors: Sex-linked genes and differing hormone profiles between males and females.
  • Behavioral & Social Factors:
  • Young men engage in higher rates of risky behaviors (e.g., motorcycle riding and accidents).
  • Suicide is a leading cause of death among men; men are $4\,\text{times}$ more likely to die by suicide than women due in part to lower rates of mental health care seeking.
  • Socialization leads men to avoid preventative medical appointments, disregard physician advice, and fail to complete prescribed medication regimens.
  • Occupational Hazards:
  • Bureau of Labor Statistics data indicate men experience higher work-related fatal injuries because they represent the majority of workers in the most dangerous industries: logging, fishing and hunting, construction, and mining.
• Racial, Transgender, and Environmental Intersections:
  • African American men experience severe life expectancy disadvantages driven by social factors: sub-par medical access, systemic racial discrimination, major discrimination episodes, and chronic stress.
  • Transgender and non-binary individuals on the transfeminine-to-non-binary spectrum face the highest mortality risks compared to non-trans individuals, driven by interacting biological and social factors.
• Historical Emergence and Policy Interventions:
  • The "female advantage" in life expectancy emerged around $1890$ and expanded during the $20\text{th}$ century (with a temporary decline during the $1918$ flu pandemic), demonstrating environmental and behavioral influences.
  • Health-promoting behaviors beneficial to all genders include a healthy diet, physical activity, non-smoking, low-to-moderate alcohol consumption, and supportive social networks.
  • Public Policy Impact Examples:
  • Russia: Historically large male-female life expectancy gap due to exceptionally high alcohol consumption among men. Policy measures prohibiting vodka sales before lunchtime yielded measurable health improvements.
  • Firearm Restrictions: Restricting access to guns reduces suicide deaths.
  • Labor Policies: Increased paid sick leave, disability insurance, and higher minimum wages correlate with reduced mortality among working-age adults.
• Global Standings:
  • The US ranks within the top $25\%$ globally for life expectancy, but trails numerous island nations and top-performing countries.
  • Healthy life expectancy geographic distribution shows marked disparities, particularly in Russia and Eastern Europe.

Healthcare Expenditure and Efficiency

• The US vastly exceeds all other nations in healthcare spending.
• Global Healthcare Expenditure Distribution:
  • US spending represents the vast majority of total healthcare expenditure in the Americas.
  • Healthcare spending in the US approaches the combined healthcare spending of the rest of the entire world.
  • China represents the second largest nation in total healthcare expenditure, yet spends substantially less than the US.
• The Spending-Outcome Paradox:
  • High spending in the US does not translate to the highest life expectancy or healthy life expectancy.
  • Public health aims to redirect healthcare resources efficiently to maximize healthy life years per dollar spent.

Historical Evolution of Leading Causes of Death in the United States

• Leading Causes of Death in 1900:
  1. Pneumonia and Influenza (Primary cause of death due to absence of modern treatments, diagnostic testing, and vaccines).
  2. Tuberculosis (Eliminated from top causes through medical and public health advances).
  3. Gastrointestinal (GI) Diseases.
  4. Heart Disease.
  5. Intracranial Lesions (Stroke/Aneurysm).
  6. Nephritis (Kidney Disease).
  7. Cancer (Ranked #8 in 1900).
  8. Senility (Equivalent to modern Alzheimer's Disease).
• Long-Term Trends for Heart Disease and Cancer:
  • Heart Disease: Has remained the #1 leading cause of death for over $125\,\text{years}$. Actual mortality rates peaked in the $1940\text{s}$ and $1950\text{s}$ before declining significantly due to public health interventions and medical treatments.
  • Cancer: Death rates rose steadily until the $1990\text{s}$ and have since been on a gradual decline.
• Recent Shifts (2019–2022):
  • Prior to $2020$, suicide was the #10 leading cause of death in the US.
  • In $2020$, COVID-19 became the #3 leading cause of death, displacing suicide from the top 10 list.
  • Comparing $2020$ to $2021$: Total COVID-19 deaths increased in $2021$ (in part because $2020$ data captured only $8$ to $9\,\text{months}$ of the pandemic vs. $12\,\text{months}$ in $2021$).
  • $2021$ saw atypical increases in deaths from heart disease, cancer, unintentional injuries, and stroke, attributed to patients delaying medical visits and hospital care during the early pandemic.
  • Each surge in COVID-19 outbreaks corresponded directly with a spike in heart disease deaths.
  • In $2022$, COVID-19 mortality dropped significantly off peak levels.

Health Disparities and Social Determinants of Health (SDOH)

• Health Disparity: A statistically significant difference in health outcomes or disease prevalence observed across specific population groups.
• Dimensions of Health Disparities:
  • Race and Ethnicity (e.g., elevated heart disease mortality in specific racial groups).
  • Sex (e.g., male vulnerability to heart disease, fatal accidents, suicide).
  • Age (e.g., increased risk of influenza, cancer, and heart disease with advanced age).
  • Disability Status.
  • Geographic Location (impacted by healthcare access and environmental factors).
  • Socioeconomic Status (SES).
• Social Determinants of Health (SDOH) Definition: The environmental conditions where people live, learn, work, play, worship, and age that affect quality-of-life and health outcomes.
• Five Main Categories of SDOH:
  1. Education Access and Quality: Higher educational attainment reduces health risks by enabling higher-paying, safer employment, safe housing options, and better health literacy.
  2. Healthcare Access and Quality: Lack of access directly elevates population risk across multiple disease categories.
  3. Neighborhood and Built Environment: Physical spaces (workplaces, schools, recreational areas) dictate health options (e.g., safe walking/running paths, presence of parks, backyard access).
  4. Social and Community Context: Social networks and community norms influencing the prevalence of health-promoting versus risky behaviors.
  5. Economic Stability: Financial stability determines affordability of medical treatments, quality food, housing, and preventive wellness activities.
• Global and Internal Health Disparity Examples:
  • Life expectancy at birth in $2015$: $50\,\text{years}$ in Sierra Leone versus $83\,\text{years}$ in Australia (a $33\text{-year}$ gap).
  • Internal Disparity in Australia: Indigenous Australians have a life expectancy approximately $10\,\text{years}$ lower than non-indigenous Australians.
  • Migration Studies: Show that migrants' disease patterns, health behaviors, and risk factors shift toward those of their destination country over time.

World Health Organization (WHO) Framework for SDOH

• Determinant Categories:
  • Individual Factors: Age, sex, genetic makeup, and health behaviors (smoking, physical activity, alcohol consumption, diet).
  • Structural Determinants:
  • Socioeconomic and political context (governance, social/economic policies, cultural values regarding health).
  • Distribution of money, power, and resources at global, national, and local levels.
  • Drives individual Socioeconomic Position (education, occupation, income, gender, race/ethnicity, social class).
  • Intermediary Determinants:
  • Material circumstances (housing quality, financial capacity for healthy food/clothing, work environment).
  • Psychosocial circumstances (stress levels, relationships, support networks).
  • Behavioral and biological factors.
  • Health systems (accessibility, quality, and type of healthcare services).
  • Bridging Determinants: Social cohesion and social capital (community willingness to collaborate for collective well-being).
• Key Principles:
  • Determinants operate non-linearly with complex, bidirectional interactions (e.g., low income leads to poor health, while chronic ill health limits workforce participation).
  • Health Inequities: Unfair, systematic, and avoidable health differences produced by structural and intermediary determinants.

Clinical, Fitness, and Public Health Applications

• Health professionals must evaluate SDOH barriers rather than relying solely on individual behavioral instructions (e.g., instructing clients to simply eat better or exercise more without addressing structural access).
• Interventions require addressing underlying structural issues: safe and affordable housing, transportation access, labor policies, and community environments.

Course Administrative and Review Details

• Study Resources: Review questions are provided on Canvas for exam preparation.
• Attendance Quiz Code: life x (capital L: Life x / life e x).