Within the broad scope of public health, which covers all efforts to reduce disease and death, there are a number of sectors, stakeholders, strategies, terms, and tools. While public health is generally understood to encompass a given group of people, you may also encounter mentions of "population health."
At its most simplest and abstract, population health refers to the health of a specific patient population. The term first rose to prominence in Canada, and it could be applied to a nation's people, or the residents of a state or county, or people who live in a specific neighborhood. In everyday use, it's now understood to mean a local population. Beyond that, however, there are varying opinions on what population health means. The conventional definition is attributed to Drs. David Kindig and Greg Stoddart, who sought to set the parameters of population health in a 2003 research paper published in the American Journal of Public Health. Kindig and Stoddardt asked, "Is it a concept of health or a field of study of health determinants?" Their conclusion was that population health should be defined as "the health outcomes of a group of individuals, including the distribution of such outcomes within the group.” Those health outcomes would include patterns of health determinants (which include things like individual behavior, genetics, societal norms, and the availability of health care), as well as interventions and other policies to address and improve them. But for many researchers and policy makers, the emphasis of population health should be more than measuring outcomes, and instead focus on the actions that need to be taken to improve them. For example the Centers for Disease Control (CDC). like many health institutions, defines population health as developing and implementing strategies to improve a population's health. It is an "interdisciplinary, customizable approach that allows health departments to connect practice to policy for change to happen locally," the CDC says. That approach involves partnerships and collaborations to achieve positive health outcomes.
Public health works to protect and improve the health of communities through policy recommendations, health education and outreach, and research for disease detection and injury prevention. It can be defined as what “we as a society do collectively to assure the conditions in which people can be healthy.” On the other hand, population health provides “an opportunity for health care systems, agencies and organizations to work together in order to improve the health outcomes of the communities they serve.”
Put another way, the alignment and interaction of stakeholders dedicated to population health can improve public health.
This put population health on the map, so to speak. And the passage of the landmark Affordable Care Act in 2010 made the "Triple Aims" the focus of a trillion dollar nationwide effort involving countless institutions, agencies, and businesses.
Population health is part of public health. Population health involves a defined group of people and involves both the study of its health outcomes and identifying the work needed to improve them. A successful population health program leads to better public health.