The term population health is much more widely used now than in 2003 when Greg Stoddart and I proposed the following definition: “the health outcomes of a group of individuals, including the distribution of such outcomes within the group.” The term is often seen in policy discussion, research, and in the name of new academic departments and institutes.

The term’s growing use, most notably in the Triple Aim and in clinical settings, has resulted in a conflicting understanding of the term today. In this post, I discuss the evolution of the term population health, and argue that going forward multiple definitions are needed. While the traditional population health definition can be reserved for geographic populations, new terms such as population health management or population medicine are useful to describe activities limited to clinical populations and a narrower set of health outcome determinants.

Origins Of Population Health Terminology

The most influential contemporary contribution to how we understand population health is Why Are Some People Healthy and Others Not? The Determinants of Health of Populations, a 1994 book by Evans, Barer, and Marmor. No definition of the term appears there, although the concept is described as, “the common focus on trying to understand the determinants of health of populations.”

In my 1997 book, Purchasing Population Health: Paying for Results, I proposed the definition as, “the aggregate health outcome of health-adjusted life expectancy (quantity and quality) of a group of individuals, in an economic framework that balances the relative marginal returns from the multiple determinants of health.” This definition included the specific measure of population health (health-adjusted life expectancy) as well as consideration of the relative cost-effectiveness of resource allocation to multiple determinants.

This definition emphasized that there are investment tradeoffs, which required “an economic framework that balances the relative marginal returns from the multiple determinants of health.” While less appreciated as a hallmark of population health thinking, the economic tradeoffs are equally important. If resources were unlimited we wouldn’t have to make investment choices, but they are limited. A critical component of population health policy has to be how the most health return can be produced from the next dollar invested, such as expanding insurance coverage or reducing smoking rates or increasing early childhood education. This is important for clinical populations as emphasized by the Triple Aim, but also for geographic populations needing resources from both public and private sectors.

In our 2003 article, Stoddart and I simplified the definition to focus on general health outcomes. We were thinking broadly about groups of individuals and suggested that “these populations are often geographic regions, such as nations or communities, but they can also be other groups, such as employees, ethnic groups, disabled persons, or prisoners.” At the time, the term typically referred to local geographic populations and had not yet been applied to the realm of medical care.

Multiple Determinants And Investment Tradeoffs

By 2003, Stoddart and I believed that the increasing emphasis on social determinants had led to an under-emphasis on specific measures of health. In response, we developed our shortened, simplified definition without the earlier emphasis on the multiple determinants of health and economic tradeoffs among them.

Some may argue that multiple determinants are so fundamental to population health that they deserve definitional status. I believe, however, that including multiple determinants in the definition could lead to confusion between the outcome goal and the determinants needed to achieve that outcome. This point is so important that the County Health Rankings grade the health of America’s counties on two components: reported outcomes (such as low birthweight), and factors determining that outcome (in the case of low birthweight, access to care and child poverty rates).

Health Disparities

The second phrase in the 2003 definition, “including the distribution of such outcomes within the group” deserves serious attention. We often state that our national and local goals are improving overall health and reducing disparities. Unfortunately in measurement, policy, and research, we often emphasize the average or overall, such as setting future life expectancy targets, but without such attention and specificity to the disparity reduction component.

A common assumption is that improving overall population health also reduces gaps by race, socioeconomic status (SES), and geography, but this is not always the case. Many times these goals compete with each other, such as quicker take up in health behaviors by more educated persons actually increasing disparities. Often policy tradeoffs are required. If we truly believe that reducing disparities by race and SES is just as important as improving overall health, we need to give them equal attention, as we did in the original 2003 definition.

The Triple Aim And Population Health Management

The past six years have seen the prominent development of the Triple Aim, which proposes three linked goals — improving the individual experience of care, reducing per capita cost of care, and improving the health of populations. This framework provided a boost in the use of the term population health.

In particular, its promotion by the Institute for Healthcare Improvement and the Centers for Medicare and Medicaid Services has led many health care organizations to use it to describe the clinical (often chronic disease) outcomes of enrolled patients. And many clinicians and medical managers have begun to use the terms population health management or population medicine. For example, the Symphonycare website defines population health management as “the iterative process of strategically and proactively managing clinical and financial opportunities to improve health outcomes and patient engagement, while also reducing costs.”

Do We Now Need Two Definitions Of Population Health?

I believe the answer is yes. Some have argued that the term should be reserved strictly for referring to geographic populations. But given how widely the term is now used in clinical settings, that is not realistic.

That is not ideal, because I believe that defining population health in terms of clinical populations draws attention away from the critical role that non-clinical factors such as education and economic development play in producing health. For this reason, I believe that when referring to patient populations, we should use the term population health management or perhaps even better, population medicine.

The traditional population health definition can then be reserved for geographic populations, which are the concern of public health officials, community organizations, and business leaders. For this reason, Jacobson and Teutsch recommended to the National Quality Forum that “current use of the abbreviated phrase population health should be abandoned and replaced by the phrase total population health.”

This will avoid confusion as the clinical care system moves rather swiftly toward measuring the health of the subpopulations they serve. Geopolitical areas rather than simply geographic areas are recommended when measuring total population health since funding decisions and regulations are inherently political in nature.

I understand this argument, but prefer that the modifiers “management” or “medicine” be used for clinical populations. I agree with the decision of the Institute of Medicine (IOM) Roundtable on Population Health Improvement, which chose “to retain the shorter term population health while acknowledging that we use it in the spirit of the Jacobson-Teutsch critique.”

Improving such total population health requires partners across many sectors—including public health, health care organizations, community organizations, and businesses—to integrate investments and policies across all determinants.

Many progressive health care organizations are doing cutting edge population health management, but are also working with other partners on total population health across geographic populations, such as the approach Health Partners board has taken in the Twin Cities. In such cases, it would be appropriate to label these efforts as population medicine expanding into total population health.

Semantics like this can seem arcane, but they also ensure that we clearly understand each other. For the next decade we need to be clear about these two ways of thinking about population health, how they interact, and the important work going on in both of them.