In this issue of Medical Care, Dr Brewster and her colleagues provide a timely and much needed report on a mechanism by which health systems might achieve greater impact on the social determinants that affect the health and health care utilization of their patient populations.1 The mechanism is the collaborative network, comprised of the health system and social services agencies, that previous work shows can reduce health care utilization by addressing the social needs of patients. In their report, Brewster and colleagues describe the nature of high-performing and low-performing networks. Although their report focuses on older adults, the approach is broadly applicable to other patient populations. It is a representative example of the emerging discipline of clinical public health.
What is clinical public health? At first glance, the term gives the impression of a discipline that is an improbable chimera, a mishmash of clinical medicine and public health that is arguably an oxymoron. Clinical medicine is highly focused on the individual—the patient—in terms of how to promote health, prevent disease, and treat the illnesses of that unique person. Public health, by contrast, is focused on the population in terms of how to promote health, prevent disease, and manage illness among the multiple persons who comprise the population. But with such disparate foci incorporated within it, the ability of clinical public health to add scientific value and hence its rationale for being, is not obvious.
Clinical public health is the interface of clinical medicine (and health systems) and public health that has as its focus the health outcomes of the individual, the determinants of those outcomes, and the policies and practices (interventions) that link the health outcomes with the determinants. It is not interchangeable with population health.2,3 The health system is not viewed as just another factor; it is a primary driver by which to improve health, but one that often needs to coordinate with public health–serving organizations. Clinical public health organizes its activities around the individual, not the population, and seeks to advance the provision of health care through health systems to promote the individual patient’s health, prevent disease, achieve earlier diagnosis, and provide appropriate treatment to reduce or eliminate the burden of disease. The array of considered activities includes efforts to manage the physical, social, and psychological determinants at the population level that affect the individual’s health. The population is seen as a reservoir of exposures that may either cause or accentuate disease or, alternatively, may be salubrious to maintaining or improving the individual’s health. Clinical public health is in keeping with the concept of “herd immunity,” wherein the emphasis is on the individual’s susceptibility to disease because that susceptibility is both influenced by, and influences, the disease risks of others in the population in which the individual resides.
In his now classic article, Geoffrey Rose reminded us that the question of “Why do some individuals have a given condition” is quite distinct from the question of “Why do some populations have much of a condition while in others it is rare?”4 Using the example of disease prevention, Rose identified the solution to the former question as a “high-risk strategy” while the latter is addressed through a “population strategy”; these strategies equate with clinical medicine and public health, respectively. To Dr Rose, the former focuses on reducing the susceptibility of the individual to exposures and the latter focuses on reducing the exposures. Rose gives priority to the population strategy (and hence public health) while duly noting that competition between the 2 strategies is “usually unnecessary.” What is left unsaid is that the more optimal approach is to pursue both strategies simultaneously: reducing or eliminating not only exposures but also the individual’s susceptibility to developing disease (or to experiencing its sequelae) among those who are exposed.
Systematic epidemiology theory is the foundation of clinical public health that allows unification of the dual foci.5 Lower described the theory of systematic epidemiology in the early 1980s, building off the much earlier conceptual work of Wade H. Frost and the relatively more recent work of Reuel Stallones.6,7 In systematic epidemiology, there are 2 arenas of action that are inextricably intertwined. One arena is that of the population in which the individual resides: this arena determines exposure to disease-causing entities, that is, population-related determinants of health, and, by logical extension, those that exacerbate disease sequelae. The other arena is internal to the individual and is comprised of the individual’s bodily response (pathophysiology) to the external exposures and hence determinants of development of disease and its sequelae once exposed. Regrettably, systematic epidemiologic theory seems to have been “before its time,” having been largely ignored by those of the scientific community who focus on public health, health services research, and other related disciplines. Yet, as we enter the era of precision medicine, this conceptual thinking of Frost, Stallones, and Lower becomes highly relevant.
Clinical public health seeks to use as well as inform the knowledge network that identifies relationships within the information commons, the latter being comprised of a broad array of information organized on the level of the individual patient.8 The information commons is populated with clinical observations made during the course of care, such as the signs and symptoms of conditions and the patient’s response to therapies. It also contains information on determinants of the individual’s susceptibility to disease, including the patient’s genome, epigenome, and microbiome, as well as determinants of disease, including the exposome (generally considered physical exposures from the environment experienced by the individual to-date), and other exposures experienced by the individual, such as social and psychological exposures, that may affect the individual’s susceptibility to developing disease. Organized and analyzed at the level of the individual, a risk-response profile for the individual is derived with which to personalize intervention (at all levels of prevention).
Clinical public health scientists utilize the information commons to make health systems more impactful. Notably, one way to achieve that goal is to identify new interventions to promote health, prevent disease, or maximize recovery of the patient, yielding protections from exposures that negatively affect the health of the individual patient. The report by Brewster and colleagues is an example of this effort to improve the functioning and impact of health systems, including the content of care and its delivery, by linking the health system to the public health infrastructure. It is pragmatic science: science that addresses real-world issues being experienced at the point of care. The solutions to those issues must be feasible, effective, efficient, and translatable sustainable (FEATS) for the health system. For those determinants of their patients’ health that derive from the community, health systems must learn to partner with their local or regional public health–oriented organizations in order to more effectively and efficiently achieve what are mutually beneficial goals. Clinical public health scientists explicitly recognize the importance of, and work intentionally within, this intersection of clinical medicine and public health.
What is clinical public health? It is the study of activities to improve the health of individuals (and, thereby, populations), engaged in by health systems, and entailing clinical medicine judiciously supplemented by public health services from public health–relevant organizations. Clinical public health is an interdisciplinary health science whose time is now.
1. Brewster AL, Yuan CT, Tan AX, et al. Collaboration in health care and social service networks for older adults: association with health care utilization measures. Med Care. 2019;57:327–333.
2. Young TK. Population Health Concepts and Methods. New York, NY: Oxford University Press; 1998.
3. Kindig D, Stoddard G. What is population health? Am J Public Health. 2003;93:380–383.
4. Rose G. Sick individuals and sick populations. Int J Epidemiol. 1985;14:32–38.
5. Lower GM. Systematic epidemiologic theory: conceptual foundations and axiomatic elements. Med Hypotheses. 1983;11:195–215.
6. Frost WHMaxcy KF. Epidemiology. Papers of Wade Hampton Frost, MD. New York, NY: Commonwealth Fund; 1941:493–542.
7. Stallones R. To advance epidemiology. Annu Rev Public Health. 1980;1:69–82.
8. Committee on a Framework for Developing a New taxonomy of Disease. Toward Precision Medicine: Building a Knowledge Network for Biomedical Research and a New Taxonomy of Disease. Washington, DC: The National Academies Press; 2011.