Ana Diez Roux Gives Milbank Lecture On Social Determinants Of Health
At Yale Centennial
Speakers are lauded in many ways when being introduced
to an audience. An unique one preceded Ana Diez Roux, professor
of epidemiology and Dean of the Drexel School of Public Health, when
she delivered the Milbank Lecture at Yale in October as part of its
centennial celebrations. Called “a walking School of Public Health” as
a testament to her background and experience, Diez Roux rose to speak
on “Population Health and Social Determinants of Health: Evidence and
Future Directions”.
Lecture Topics
She began her presentation by highlighting a handful of
key facts about social determinants, followed up with mention of three
important gaps or unanswered questions relating to social
determinants, and finished the lecture by discussing areas where she
believes additional research could be most helpful.
Key Facts
Among the things we know about social determinants is
that social position is a powerful predictor of health. It acts in a
dose response manner to create graded relationships for many health
processes. Social position is generally very persistent over time,
produces similar effects across societies, across age groups, and
across many diseases and causes of disease. Some heterogenerities in
the social patterning do exist and may provide clues about the drivers
of patterns or to possible interventions.
There are multiple dimensions or components that make up
social circumstances and these may interact with each other. Examples
include income, education, and race/ethnicity. These elements may
operate at different times over the lifecourse and how they act early
in life can influence events at later ages. There are multiple
pathways by which social position exerts its influence. Social
determinants manifest themselves at multiple levels, for example, at
both the level of the individual as well as the neighborhood level.
Gaps in Knowledge
There are important questions still unanswered noted
Diez Roux. The first of these she described is a question many
observers will ask, namely, how much variation in health do social
determinants explain? Efforts have been made in pie chart or other
forms to parcel out the contributions of social determinants, however
these parcels have really
not been quantified, and the question remains
unanswered. The reasons for this, Diez Roux stated, are the
difficulties of measuring the components themselves, the fact that
they are inter-correlated, and not knowing the causal ordering of the
different components. Diez Roux wondered whether the question is one
that should be asked, or if it is really a right question.
Mediating Processes
A second gap in knowledge has to do with the mediating
processes which explain the social determinants of health. It turns
out that known risk factors for certain diseases do not always explain
a large part of the variance and investigators have sought to
determine if behavioral, psychosocial, or material resources could
fill in the gap. These efforts have not yet succeeded, said Diez Roux,
because social position appears to operate through complex causal
chains. Such complex systems “remains a tricky problem” she said.
Policies and Strategies
A third area with gaps in knowledge pertains to what
policies and strategies should be implemented to address social
position or social circumstances. Here Diez Roux introduced the
concept of “fundamental social causes” and pointed out that to reduce
the gradient in outcomes due to social position, the fundamental
elements of social position such as power, knowledge, and resources
must be tackled.
Why Study
Some have asked why bother to study social determinants
at all since we know the fundamental causes already.
Diez Roux gave several reasons why it is important to
continue to study social determinants.
First, the gradient in outcomes is not invariant. This
suggests that changes could also be brought about with interventions.
What we learn about mechanisms which produce varying outcomes could
teach something important about the causes of disease more generally.
Another reason to conduct social determinants research is
that while we may know fundamental social causes, it is not always
obvious what intervention to carry out. She cited the example of cash
transfers, too rapid economic growth, and the mixed effects of
neighborhood level interventions to illustrate the difficulties of
designing effective interventions related to social circumstances.
According to Diez Roux, the policy implications of knowledge
about social position are difficult to decipher because the causes are
very distal, i.e., have a long latency, are context dependent, and
randomized trials are not feasible to carry out.
Opportunities for Additional Work
Given the challenges she articulated Diez Roux was able
to point out the need for more research in several categories.
1. Etiologic research in the broad sense
Here she called for better methods to improve causal
inference using the observational data we have, integrating new types
of data such as those from electronic health records, and more systems
thinking and modeling.
2. Mechanistic understanding and creating more
plausible causal pathways
3. Policy development and evaluation
She called for looking at more policies with possible
health consequences such as those related to transportation, and for
broadening the tools used by taking advantage of natural experiments
or engaging in more systems thinking. Importantly, she called for a
tighter or more iterative connection between research and action and
using evaluation of interventions as feedback to better inform the
next wave of research.
4. Dissemination and translation
In this arena, Diez Roux argued for giving more thought
to how dissemination and implementation research can be applied not
just to translation of clinical findings but to population level
interventions as well.
She also called for novel uses of data to help change perceptions
about the social drivers of health. At present, she speculated that
most people when asked
about the causes of
health
would answer genes, behavior, and medical care and not
single out or include social circumstances.
Closing Remarks
She ended her presentation by calling for a broadening
of conceptual approaches and tools used to study social position. She
acknowledged the successes of reductionist approaches to the study of
phenomena but said that these models identify single factors and are
not the most helpful in studying phenomena with many feedback
dependencies. She called for more systems approaches and for learning
through action.
She closed with a favorite quote from Jay Wright
Forrester a pioneer computer engineer and systems scientist at MIT
who said about complex systems “causes
are usually found, not in prior events, but in the structure and
policies of the system.“■
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