CENTER ON SOCIAL DISPARITIES IN HEALTH
University of California, San Francisco
When do we know enough to act on
the social determinants of health?
Center for Public Health Initiatives
University of Pennsylvania
Philadelphia
February 12, 2013
Paula Braveman, MD, MPH
Professor of Family & Community Medicine
Director, Center on Social Disparities in Health
University of California, San Francisco
CENTER ON SOCIAL DISPARITIES IN HEALTH
University of California, San Francisco
Evidence-based medicine
• Long overdue response to basing Rx on opinion
• Hierarchy of evidence to infer
causation/effectiveness:
• Gold standard: RCTs
• Cohort studies
• Case-control
• Other designs considered weak
CENTER ON SOCIAL DISPARITIES IN HEALTH
University of California, San Francisco
Limitations of evidence-based medicine (EBM)
approach in general
• Randomization not always feasible or ethical
• Quality of RCTs sometimes not considered
• A well-designed and conducted observational study vs a
poorly designed/executed RCT
• Lack of generalizability
• Often little information about context
UPSTREAM:
At or near the source of a cause of ill health
DOWNSTREAM:
Near where health effects are seen
The social determinants of health:
considering the causes of the causes
Economic & Social
Opportunities & Resources (e.g.
Income, education, racial inequality)
Living & Working Conditions
in Homes & Communities
Medical
Care
Personal
Behavior
HEALTH
Robert Wood Johnson Foundation Commission to Build a Healthier America www.commissiononhealth.org
How could income affect health?
A body of literature supports, for example:
Income can shape options for:
• Housing
• Neighborhood conditions
• Nutrition
• Physical activity
• Services (e.g., childcare,
transportation, repairs,
medical care…)
• Alleviating stress
Parents’ income shapes
the next generation’s:
• Education
• Work
• Income
Education can shape health behaviors by
determining knowledge and skills
Educational
attainment
Health
knowledge
Literacy
Problemsolving
 Coping skills
Diet
Exercise
Smoking
Health/disease
management
Other plausible pathways from education to
health, e.g., via work & income
Income
Educational
attainment
Work
Neighborhood
environment
(including schools)
Diet & exercise
options
Stress
Workrelated
resources
Health insurance
Sick leave
Wellness programs
Stress
Working
conditions
 Control / demand
imbalance
Stress
HEALTH
Income shapes neighborhood
options. How could a
neighborhood affect health?
 Safe places to exercise






Access to healthy food
Ads for harmful substances
Social networks & support
Norms, role models, peer pressure
Fear, anxiety, despair, stress
Quality of schools
CENTER ON SOCIAL DISPARITIES IN HEALTH
University of California, San Francisco
The stress-health link: Biologically plausible?
• Advances in neuro-science & psycho-neuro-immunology help
elucidate how social factors like income, education, & racial
discrimination can “get into the body”
• HPA axis, sympathetic nervous system, and
immune/inflammatory mechanisms have been demonstrated
as responses to stress
– Relative importance of specific mediators/markers (e.g.,
cortisol, C-reactive protein, cytokines, telomerase) not
established
• Chronic stress is a plausible and likely major contributor to
both socioeconomic and racial/ethnic inequalities in health
Psychosocial pathways
from education to health
Educational
attainment
Social
standing
Social & economic
resources
Perceived status
Stress
Social
networks
Social & economic
resources
Norms
Social support
Stress
Control beliefs
(powerlessness,
sense/locus of
control, fatalism,
mastery)
Coping
Response to
stressors
HEALTH
How could education affect health?
Educational
attainment
Health knowledge,
literacy, coping & problem
solving
Working
conditions
Educational
attainment
Work
Work-related
resources
Income
Educational
attainment
 Diet
 Exercise
 Smoking
 Health/disease management
HEALTH
 Exposure to hazards
 Control/demand imbalance
 Stress
 Health insurance
 Sick leave
 Wellness programs
 Stress
HEALTH
 Housing
 Neighborhood environment
 Diet & exercise options
 Stress
Control beliefs
 Coping & problem solving
 Response to stressors
 Health-related behaviors
Social standing
 Social & economic resources
 Perceived status
 Stress
Social networks
 Social & economic resources
 Social Support
 Norms for healthy behavior
 Stress
HEALTH
HEALTH
What produces and reproduces health disparities
across the life course and across generations?
SOCIETY
Social
Context
INDIVIDUAL
1. Social stratification
Social position by
race & class
2. Differential
exposure
Specific exposure
3. Differential
vulnerability
Disease
4. Differential
consequences
Policy
Context
5. Further social stratification
Adapted from Finn Diderichsen, U. Copenhagen
Social
consequences
of ill health
13
CENTER ON SOCIAL DISPARITIES IN HEALTH
University of California, San Francisco
Long, multiple, complex pathways
• Pathways from social factors to health are often
long and complex
• Interactions with characteristics of people and
settings, at each step in causal chain
• Health effects of social factors may not manifest for
decades or generations
• Randomization likely to be unfeasible or unethical
• Does this mean we will never have good evidence?
CENTER ON SOCIAL DISPARITIES IN HEALTH
University of California, San Francisco
Should we give up?
• Techniques to reduce likelihood of confounding and
bias in observational research
• Multivariate analysis, stratification, instrumental
variables, propensity score matching…
• Critical thinking: rigorously looking for potential
bias due to unmeasured differences
• Connect the dots – knowledge linkage – chains of
inference
CENTER ON SOCIAL DISPARITIES IN HEALTH
University of California, San Francisco
Connect the dots
• We may lack evidence directly linking social factor
A  health outcome C
• But we may have evidence linking A  B (e.g.,
educational attainment) and B  C
• May be from another discipline/field
• Build knowledge of SDOH by linking knowledge of
pathway segments, acknowledging limitations
• Done all the time in medicine --targeting risk
factors (e.g., cholesterol, blood pressure)
CENTER ON SOCIAL DISPARITIES IN HEALTH
University of California, San Francisco
Evidence-based medicine’s hierarchy of
evidence is peculiar to medicine
• Civil law: preponderance of evidence
• Criminal law: beyond a reasonable doubt
• Similar approaches in commerce and economic
policy
• Has the Air Force conducted RCTs to determine
whether they should supply parachutes to
paratroopers?
• Best available knowledge
CENTER ON SOCIAL DISPARITIES IN HEALTH
University of California, San Francisco
Is lack of evidence always the problem?
• Obstacles to translating the knowledge we have
into interventions
• Often we have knowledge of pathways and
mechanisms but don’t know how to translate it
into effective, efficient interventions
• Political obstacles
• Often the obstacle is lack of political will
CENTER ON SOCIAL DISPARITIES IN HEALTH
University of California, San Francisco
When do we know enough to recommend
action on the SDOH?
• Need a broader conception of what counts as evidence
•
•
•
•
Build on and broaden – don’t discard – EBM principles
Require rigor in all study designs
Consider range of sources of evidence, including qualitative
Connect the dots from A  B and B  C
• Policy should be informed by best available knowledge &
critical thinking; consider long-term consequences
• Need bold experiments testing the most promising directions,
based on current knowledge
• Weigh costs of acting vs. costs of status quo