Precision Public Health: More Precision Ahead for Individual and Population Interventions
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In August 2016, we published a point-counterpoint viewpoint asking a crucial question that has been on the minds of researchers, health care providers and the public health community: “will precision medicine improve population health?” We understood that we were tackling “the elephant in the room” and hoped for reactions to this viewpoint. We were pleased that Dr. Ron Zimmern, chairman of the PHG Foundation in Cambridge, UK and a leader in the global public health genomics movement, offered his thoughts. In his piece, he advocated for creating “a united vision for health” that does away with “the sterility of pitting the public health approach against precision medicine.”
We do think the tension around precision medicine and population health is real and not “entirely of our own making.” Nevertheless, we fundamentally agree with Dr. Zimmern that to improve health, we need to take into account all possible interventions, ones that are targeted at the individual (e.g., treatment or prevention) and ones that are population-wide and not targeted to specific individuals (e.g. policy, environment, housing and education, among others). Our main thesis is that advances in technologies of precision medicine (i.e., beyond genes, drugs and diseases) could, in time, develop, evaluate and deliver health interventions with more “precision” both for individuals and populations. This is our view of precision public health.
In order to continue the dialogue, we would like to elaborate on the two key concepts of population health and precision medicine. First, Dr. Zimmern asserts, “a population is no more than a group of individuals.” While this may be strictly correct, we think this statement can actually miss the point we were trying to make. The health status of any individual is intimately tied not only to his or her biology, and clinical care, but also to geopolitical, environmental and socioeconomic factors. If we take a population of a million people who live in a certain area and “transplant” them into another place, country or continent, the health outcomes of these same individuals in this new “population” could be radically different depending on the environmental conditions, type of health care and socioeconomic differences between the two places. Population health considers multilevel determinants including the interaction of our biology with external forces. Dr. David Kindig recently reviewed the evolution of the term population health. Some have argued that the term population health be reserved strictly for geographic populations. But the term is now widely used in clinical settings (e.g. population medicine), which may draw attention away from the critical role that non-clinical factors such as education and economic development play in producing health. A fundamental concern to population health is health equity— ensuring that all members of a community benefit from available health related services, whether targeted to individuals or to the whole group.
Second, we recognize that the term precision medicine is too narrowly interpreted as “personalized medicine with a heavy focus on treatment.” As Dr. Zimmern states, “Precision medicine is this second type of intervention, since it is targeted at individuals and can only achieve its effect if those individuals comply with what is offered to them.” In a recent blog, I discussed that, over time, there has been an increasing shift from the term personalized medicine to precision medicine. While the term personalized medicine implies individual level intervention, the term precision medicine if interpreted in the context of multiple determinants of health, can lead to both individual and population interventions. We gave several examples of early uses of precision public health in recent articles (see here and here).
Thus, as the practice of medicine becomes more precise in the next few years, what we can do for a whole population will also become more precise. This is similar to the concept that Dr. Sue Desmond-Hellman, CEO of the Gates Foundation, has been promoting. In a recent commentary in Science magazine, she wrote:
“Too often, I feel as though I live in two worlds. One is populated by scientists working on advanced tools, such as big data, sequencing, and data-based disease surveillance. The other is populated by public health professionals working on the demanding challenges of combating infectious diseases, empowering women and girls, and ensuring that more children survive and thrive… By more accurately detecting, identifying, and tracking health problems in subpopulations, subgroups, or even communities, we can respond with greater precision.”
If we want to improve global health and health equity, it is time to heal the schism between medicine and public health. By bringing the two worlds closer together, precision public health could help more effectively harness the power of the new tools of science and technology, including genomics, big data and predictive analytics to improve the health of individuals and populations.
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Uniting Precision Medicine, Clinical Prevention, Clinical Care, Population Health, Public Health:
1) Biopsychosocial Model of Interaction and Intervention
2) Integration of factors causing Onset (Risk & Protective Factors), Progression (Stress – physical, psychological, interactional, cognitive, spiritual, cultural, motivational, behavioral…..etc – & Resistance Factors), Recovery (Antagonistic & Resilience Factors), Complication (Risk & Protective Factors), Palliation of (from) Disease.
3) Understand the importance of the microvascular system for integrating matter, mind, mood, motivation, social interactional……etc effects on wellness, health status, risk of disease and intensity of disease. For example how can depression be a risk factor for so many conditions AND so many conditions be a risk factor for depression except through the mediation of the microcirculation?
4) Understand the importance of oxidative stress, reactive oxygen species signaling systems gone awry,, EPIGENETIC activation of NF-kB and lack of activation of Nrf2 in the development of mitochondrial dysfunction, microvascular dysfunction / neurovascular unit dysfunction / regional blood flow abnormalities and downstream ischemia based pathologies
5) Understand the Power of Stories and the sacredness of the doctor patient interaction and continuity of care to good outcomes, that after all is the goal of public health, precision medicine, clinical prevention, clinical care, palliative care and continuity of care.
6) Understand that community-up versus middleman down monitoring and control of care must be the goal IF we are truly going to integrate public health, precision medicine, evidence-based medicine……efficacious / COST EFFECTIVE interventions for the purpose of continuous improvement of outcomes
7) Understand that we currently are on an unsustainable course with regard to the above and only a revolution in medical education, prioritization of “unlimited / unhindered primary care” within a budget AND having specialists be the monitors of waste fraud and abuse in “higher more expensive tiers” of health care will there be a significant cutting of the Gordian Knot of practicing very cost-effective care, AND guardianship of the self / family / community with “skin in the game” down to the street level.
I am delighted that Dr Muin Khoury has taken the trouble to reply to my comments. Although some may take this dialogue to be somewhat esoteric, I think both of us will be of the view that the arguments have real practical implications.
We both agree that the tension between population and clinical medicine is real, but we need to understand that this has existed for many decades and is not a consequence of either genomics or of precision medicine. It is just that genomics and precision medicine has brought this into greater relief and perspective. Kerr White, of the Rockefeller Foundation realised over 25 years ago that such a schism existed and tried to use clinical epidemiology as the tool for bridging the divide. Dr Khoury’s thesis expresses the hope that “advances in technologies of precision medicine” might in time be of advantage for both populations and individuals, but points out that while my assertion that “a population is no more than a group of individuals” may be strictly correct, it misses the point that health status is tied not just to biology but to “geopolitical, environmental and socio-economic factors”. I agree totally and unreservedly with his view that health status is the result of the interaction between these external with inate biological factors. In our writings, both of us have tried to make this clear, and to say to our public health colleagues that what they believe to be important about the wider determinants of health, we also believe to be of the greatest importance.
The intention of my assertion was not to deny the existence or importance of these wider determinants. It was to make the point first, that the link between populations and individuals is that, no matter how one defines a particular population, the population is no more and no less than the set of those individuals so defined; second, that because biology works through individuals (and not through populations), those geopolitical, environmental and socio-economic factors must exert their population effects through biological mechanisms in individuals within that population; and third, that because we can in fact define populations in whatever way we like, populations are socially constructed, unlike individuals who have a reality that does not depend on definitional criteria. The consequence of these statements is that I believe there to be a critical difference between an intervention that one makes on the external world (whether through environmental, social, political or economic manipulation), an intervention that pays no attention to the differences between individuals; and interventions specifically directed at and possibly even tailored to individuals.
If that distinction is admitted, then we need to agree whether it is only the first type of intervention that is the proper work of public health professionals (leaving interventions on individuals to clinicians), or whether public health professionals are in their professional life to embrace both types of interventions. This is a very practical question that has implications for training and for practice. I have no real bias towards the one or the other, but I do believe that those in public health need to face up to the fact that disease prevention involves not just generalised attention to the wider determinants but also to more specific preventive clinical interventions; and to decide whether the second of these come within their professional remit or whether they wish clinicians to take on that agenda in the coming decades.
The second area on which Dr Khoury comments concerns the term ‘precision medicine’. He makes the point that there is a distinction between ‘personalised medicine’ and ‘precision medicine’, and that while the former “implies individual level intervention, the term precision medicine if interpreted in the context of multiple determinants of health, can lead to both individual and population interventions”. My own practice had been to use the two terms interchangeably, and to suggest that their essence is of an approach that
(a) treats individuals as whole persons
(b) empowers them to take greater responsibility for their own health
(c) manages their care in accordance with their biological characteristics and risk
But on this point I am happy to agree with Dr Khoury. Whereas one can apply the term ‘precision medicine’ to what he calls “population based interventions” (what I would prefer to refer to as my first type of intervention, one directed at “the external world” rather than at the individual) it would be somewhat of an oxymoron to refer to this this as ‘personalised medicine’. But that is by and large a semantic point.
The greater importance, however one choses to refer to it, lies in understanding that:
(a) externally generally directed interventions need to be conceptually separated from those directed specifically at individuals
(b) for those externally generally directed interventions greater precision may be applied to the detection, identification, evaluation and tracking of health problems in populations and subpopulations
As to Dr Khoury’s closing remarks I could not agree more: “If we want to improve global health and health equity, it is time to heal the schism between medicine and public health. By bringing the two worlds closer together, precision public health could help more effectively harness the power of the new tools of science and technology, including genomics, big data and predictive analytics to improve the health of individuals and populations.” I would only add that we must supplement this with the personal approach I set out above, an approach for which either term might legitimately be used.