Abstract
Chronic, noncommunicable diseases have replaced acute, infectious diseases as the leading causes of global mortality and morbidity. Efforts among physical therapists to address noncommunicable diseases have primarily focused on the promotion of healthy behaviors among individual clients. However, the strongest predictors of chronic disease are tied to where we live, work, learn, and play, our families, and our communities. Population health frameworks can help us better understand the complex interrelations between individuals’ health condition and their social and physical environment over time and also inform the development of effective programs and policies that improve the health of individuals and communities. The objectives of this article are to: (1) define population health, prevention, and health promotion; (2) provide a current perspective on the utility of population health frameworks in physical therapy; and (3) identify opportunities for the expanded use of population health frameworks in physical therapist practice, research, and education.
The last century witnessed an epidemiological shift as chronic, noncommunicable diseases (NCDs) such as heart disease, stroke, chronic obstructive pulmonary disease, cancer, and diabetes replaced acute, infectious diseases as the leading causes of mortality and morbidity globally.1 Ostensibly, NCDs are largely preventable through the promotion of healthy behaviors, including healthy eating, active living, and smoking cessation. However, the strongest predictors of individual health behaviors and by extension, NCDs, lie beyond the individual and the health care system. Health starts where we live, learn, work, and play; within our families, neighborhoods, and communities. It is influenced by our ability to access nutritious foods and safe recreational areas, by the air we breathe, and by the water we drink.2 Our current health care system, perceived by many as a sick-care system, is ill-equipped to address these multiple and complex determinants of health and meet societal needs in a fiscally sustainable manner. As a result, the system is evolving from one focused on chronic disease management among individuals to one focused on disease prevention and health promotion within populations. Public health practitioners, nurses, and physicians have led this most recent health system evolution, and although physical therapists have made important contributions (eg, injury prevention), there is much more we can and should do to meet societal needs. To help augment physical therapists’ understanding and action in the areas of prevention and health promotion that reach beyond the individual, we propose expanding the use of population health frameworks in all aspects of physical therapist practice, research, and education. The objectives of this article are to: (1) define population health, prevention, and health promotion; (2) provide a current perspective on the utility of population health frameworks in physical therapy; and (3) identify opportunities for the expanded use of population health frameworks in physical therapist practice, research, and education. Our use of the term physical therapist practice applies to both physical therapists and physical therapist assistants.
Terminology
Population health has been defined as “the health outcomes of a group of individuals, including the distribution of such outcomes within the group.”3 Traditional definitions of population health are reserved for geopolitical populations (eg, neighborhoods, cities, or states), whereas terms such as “population health management” and “population medicine” refer to the application of population health to defined clinical populations.4 Population health can be thought of as a “strategy for understanding the health of populations,” or an approach that “focuses on interrelated conditions and factors that influence the health of populations over the life course, identifies systematic variations in their patterns of occurrence, and applies resulting knowledge to develop and implement policies and actions to improve the health and well-being of populations.”5 These definitions evolved from the book by Evans, Barer, and Marmor, Why Are Some People Healthy and Others Not? The Determinants of Health of Populations.6 This seminal work focused on understanding the multiple determinants, or factors, that influence the health of populations (genetics, individual health behaviors, health care, and the social and physical environments), and serves as the foundation of many population health frameworks. According to Carpiano and Daley, frameworks outline a set of variables believed to account for a particular phenomenon, and set the stage for theories that further elucidate the nature of the relations underlying the phenomenon. Nested within frameworks and theories are models. Models illustrate the relations between a narrow set of variables, and can suggest causality or directionality.7 This Perspective article will focus on the utility of population health frameworks in physical therapist practice, research, and education.
Prevention and health promotion represent strategies for improving population health. Prevention generally refers to efforts aimed at avoiding or arresting disease processes. The concept of prevention is perhaps best understood in the context of levels: primordial, primary, secondary, and tertiary (Fig. 1).8Primordial prevention refers to conditions within the social, economic, or physical environment that minimize the emergence of factors known to increase disease or injury risk (eg, development of healthy eating patterns early in life). Primary prevention refers to the amelioration of specific risk factors (eg, obesity) in susceptible populations. Secondary prevention involves the early detection of disease (eg, type 2 diabetes) during a detectable, asymptomatic period through clinical and population-based screening. The United States Preventive Services Task Force has established screening principles, which include the need for evidence that screening improves health outcomes, and that the benefits of screening outweigh the risks.9Tertiary prevention is defined as actions taken to limit disability and improve length and quality of life among individuals who are symptomatic (eg, rehabilitation for individuals with lower limb amputation secondary to diabetic peripheral neuropathy). This level most closely aligns with historical views of physical therapist practice, and somewhat limited views of contemporary practice.
Levels of prevention. The inverted triangle represents the relative number of individuals whose health can be influenced at each level.
Health promotion is closely tied to prevention, and refers to the process of empowering people to increase control over their health, moving beyond a focus on individuals to consider social, cultural, and political environments that limit individual choice and opportunity.10 As such, health promotion becomes the responsibility of agencies in both health and nonhealth sectors (eg, housing, transportation, education). The World Health Organization (WHO) identifies 3 pillars of health promotion: good governance, healthy cities, and health literacy. Good governance involves widespread promotion of health behaviors through conducive laws, policies, and regulations. Healthy cities refers to public planning and engineering initiatives that promote healthy environments, safe recreational spaces, and active transportation. Health literacy involves efforts to improve health-related knowledge and encourage the adoption of healthy behaviors among social networks. Health promotion programs can exist within various levels of prevention, and often involve the adaptation of programs for communities or individual group members. Relatedly, health protection, vis-à-vis public health, involves the creation and implementation of policies and legislation that manage disease outbreaks and protect against environmental hazards (eg, chemical, biological, and radioactive).11 It is what “we as a society do collectively to assure the conditions in which people can be healthy.”12
Current Perspectives on the Utility of Population Health Frameworks in Physical Therapy
Expanding the physical therapist scope of practice to include prevention and health promotion as a means of improving population health and addressing contemporary health priorities is not new.13–15 In 2009, Dean authored a 2-part introduction to the practice of physical therapy in the 21st century.16,17 In it, she succinctly described the rationale for an evidence-informed practice framework that aligns with WHO, summarizes the epidemiology of NCDs, and outlines a “health-focused strategy” to be used in physical therapist practice. The first and second physical therapy summits on global health further acknowledged our profession's responsibility in addressing global health priorities through the prevention and management of NCDs and informed the development of a physical therapy action plan to address lifestyle-related conditions.18,19 These positions align with the International Classification of Functioning, Disability and Health (ICF), which the profession has adopted as its guiding framework in contemporary physical therapist practice.18,20,21
The ICF is a biopsychosocial framework that integrates major models of disability and is used across international agencies to organize disability-related information and provide a standard language and conceptual basis for defining disability.22 The 2 main components of the ICF are: (1) functioning and disability, and (2) contextual factors. Functioning and disability consider the relations among physical phenomena within the individual: body structure and function, activities, and participation. Contextual factors comprise personal and environmental characteristics pertaining to the individual that can affect functioning and/or disability.
Key strengths of the ICF framework over traditional biomedical frameworks are: (1) its adoption of WHO’s definition of health as “a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity”; and (2) its attention toward personal and environmental factors and their influence on health. Nevertheless, the ICF at its core is a classification system, replete with checklists used to describe various aspects of an individual's health and disability. Personal factors are not classified using the ICF, yet the documentation of personal factors relevant to the functioning of the individual is encouraged “using standard classifications where they exist.”23 These personal factors can include, but are not limited to, gender, race, age, lifestyle, education, and occupation.
It is perhaps within the context of these personal factors that population health frameworks extend the ICF to reflect contemporary perspectives about what it means to be healthy. Population health frameworks emphasize these personal factors and place them within the broader context of the multiple determinants of health. We are born with a genetic blueprint that influences our future health, yet there is unequivocal evidence that behavioral and social determinants (loosely defined in the ICF as “personal factors”), and environmental determinants are the strongest predictors of health across the life course.24–27 Such evidence, informed by population health frameworks, has revealed a complex process by which biological, behavioral, social, and environmental determinants interact to influence gene expression, modify physiological pathways, and shape short- and long-term health trajectories. WHO’s conceptual framework for action on the social determinants of health contends that distributions of health and disease cannot be reduced to linear, mechanistic-oriented relationships28 as one might be tempted to do using ICF clinical checklists.
We propose the adoption of population health frameworks in all aspects of physical therapist practice, research, and education to augment our understanding of the health of populations (beyond the functioning of individuals with specified health conditions), identify disparities and systematic variations in health outcomes and related determinants, and inform actions that serve to improve the health and well-being of populations.
Population Health Frameworks
One of the earliest population health frameworks to illustrate the ways in which multiple determinants, or factors, interact to influence health is the Evans and Stoddart framework published in 1990 (Fig. 2). This framework builds upon the central relation between health care and disease to more accurately capture the influence of genetics, individual responses, and the social and physical environment on health and function, well-being, and prosperity.29 The framework intentionally highlights broad factors thought to influence a number of health outcomes in diverse populations.
The multiple determinants of health.29 Reprinted from Social Science and Medicine, 31(12), Robert G. Evans and Gregory L. Stoddart. Producing Health, Consuming Health Care. 1347–1363, 1990, with permission from Elsevier.
More contemporary population health frameworks have integrated a life course perspective to broaden our conceptualization of health, human development, and aging as the product of individuals and their environment over time.30–32 The Life Course Health Development framework30,33 views health “as a dynamic, emergent capacity that develops continuously over the lifespan in a complex, non-linear process.” Further, health development is an adaptive process, sensitive to the timing and social structuring of risk and protective factors. Beginning in 2010, the Maternal and Child Health Bureau adopted the Life Course Health Development framework as the foundation of its research and policy endeavors.
Application of Population Health Frameworks in Physical Therapist Practice, Research, and Education
The following section outlines the ways in which population health frameworks might be applied in contemporary physical therapist practice, research, and education. These recommendations are summarized in the Table.
Application of Population Health Frameworks in Physical Therapist Practice, Research, and Education
| Activity | Application |
|---|---|
| Practice | Enhance monitoring and surveillance of clinical populations |
| Identify systematic variations in clinical processes and disparities in health-related outcomes | |
| Draw attention to the limitations of individual-level interventions as a means of addressing chronic noncommunicable disease (NCD) and disability | |
| Facilitate the identification of potential collaborators within and outside the health sector | |
| Inform the design, implementation, and evaluation of integrated services, programs, and policies | |
| Research | Guide the development of conceptual models that can be systematically tested to establish the nature, strength, and directionality of relationships |
| Inform the development of a holistic set of health indicators and the creation of informative data linkages | |
| Guide the development of quality improvement initiatives or community-based programs as a means of reducing health disparities | |
| Inform the development of robust prediction models that serve as the foundation for “precision physical therapy” | |
| Education | Serve as a foundation for entry-level physical therapist competencies and curricular guidelines in the areas of prevention and health promotion |
| Strengthen the effectiveness of pro bono services by informing the identification of root causes of health inequities, and guiding the development of community and intersectoral partnerships |
| Activity | Application |
|---|---|
| Practice | Enhance monitoring and surveillance of clinical populations |
| Identify systematic variations in clinical processes and disparities in health-related outcomes | |
| Draw attention to the limitations of individual-level interventions as a means of addressing chronic noncommunicable disease (NCD) and disability | |
| Facilitate the identification of potential collaborators within and outside the health sector | |
| Inform the design, implementation, and evaluation of integrated services, programs, and policies | |
| Research | Guide the development of conceptual models that can be systematically tested to establish the nature, strength, and directionality of relationships |
| Inform the development of a holistic set of health indicators and the creation of informative data linkages | |
| Guide the development of quality improvement initiatives or community-based programs as a means of reducing health disparities | |
| Inform the development of robust prediction models that serve as the foundation for “precision physical therapy” | |
| Education | Serve as a foundation for entry-level physical therapist competencies and curricular guidelines in the areas of prevention and health promotion |
| Strengthen the effectiveness of pro bono services by informing the identification of root causes of health inequities, and guiding the development of community and intersectoral partnerships |
Application of Population Health Frameworks in Physical Therapist Practice, Research, and Education
| Activity | Application |
|---|---|
| Practice | Enhance monitoring and surveillance of clinical populations |
| Identify systematic variations in clinical processes and disparities in health-related outcomes | |
| Draw attention to the limitations of individual-level interventions as a means of addressing chronic noncommunicable disease (NCD) and disability | |
| Facilitate the identification of potential collaborators within and outside the health sector | |
| Inform the design, implementation, and evaluation of integrated services, programs, and policies | |
| Research | Guide the development of conceptual models that can be systematically tested to establish the nature, strength, and directionality of relationships |
| Inform the development of a holistic set of health indicators and the creation of informative data linkages | |
| Guide the development of quality improvement initiatives or community-based programs as a means of reducing health disparities | |
| Inform the development of robust prediction models that serve as the foundation for “precision physical therapy” | |
| Education | Serve as a foundation for entry-level physical therapist competencies and curricular guidelines in the areas of prevention and health promotion |
| Strengthen the effectiveness of pro bono services by informing the identification of root causes of health inequities, and guiding the development of community and intersectoral partnerships |
| Activity | Application |
|---|---|
| Practice | Enhance monitoring and surveillance of clinical populations |
| Identify systematic variations in clinical processes and disparities in health-related outcomes | |
| Draw attention to the limitations of individual-level interventions as a means of addressing chronic noncommunicable disease (NCD) and disability | |
| Facilitate the identification of potential collaborators within and outside the health sector | |
| Inform the design, implementation, and evaluation of integrated services, programs, and policies | |
| Research | Guide the development of conceptual models that can be systematically tested to establish the nature, strength, and directionality of relationships |
| Inform the development of a holistic set of health indicators and the creation of informative data linkages | |
| Guide the development of quality improvement initiatives or community-based programs as a means of reducing health disparities | |
| Inform the development of robust prediction models that serve as the foundation for “precision physical therapy” | |
| Education | Serve as a foundation for entry-level physical therapist competencies and curricular guidelines in the areas of prevention and health promotion |
| Strengthen the effectiveness of pro bono services by informing the identification of root causes of health inequities, and guiding the development of community and intersectoral partnerships |
Practice
With respect to practice, population health frameworks can serve to inform our roles in tertiary and secondary prevention, primary prevention and health promotion, and primary care. Physical therapists play a critical role in tertiary and secondary prevention through the treatment of individuals with structural or functional impairments, activity limitations, and participation restrictions related to musculoskeletal, neuromuscular, cardiovascular, pulmonary, and/or integumentary conditions.34 Clinical tracking systems mostly focus on singular health conditions with little attention paid to activity- or participation-level outcomes, or related comorbidities. Moreover, there is a general lack of consideration, operationalization, and measurement of behavioral, social, or environmental factors known to influence clinically relevant outcomes. Population health frameworks can serve to enhance the monitoring and surveillance of these clinical populations by informing the collection of a more holistic set of health indicators and related determinants within the electronic health record. Armed with such information, physical therapists and clinic managers would be better positioned to identify systematic variations in clinical processes and disparities in health-related outcomes. Such information could then be used to inform the development and implementation of activities aimed at enhancing service efficiency and improving the health of clinical populations.35–39
In addition to providing rehabilitation services (secondary and tertiary prevention), physical therapists contribute to primary prevention and health promotion efforts,18,19,34 and play an important role in the provision of primary care,34 when defined as “the provision of integrated, accessible health care services by clinicians who are accountable for addressing a large majority of personal health care needs, developing a sustained partnership with patients, and practicing within the context of family and community.”40 As a result, it is critical that physical therapists recognize the influence of multiple, interconnected factors on the health of populations, and understand the risk and protective factors affecting clients, families, and communities. Social and environmental factors (eg, education and safety) are known to contribute substantially to a population's health, yet limitations in the measurement of these factors and the subsequent interpretation of risk reinforce the misconception that health, illness, or disability are individual-level phenomena that should be treated at the individual level. Population health frameworks help draw attention to the limitations of such individualistic interpretations of health, and force us to consider the complex influence of social and environmental factors on long-term health. Examples of physical therapists working to understand and ameliorate the social and physical environments include our involvement in employer-based initiatives,41,42 community-based health promotion programs,43–46 inclusive community design,47 and health policy.48
There is overwhelming evidence to suggest that effective interventions must target the constellation of determinants that influence health, and if we as physical therapists are serious about our role in prevention, health promotion, and primary care, then we must recognize that the health-related needs of our clients extend beyond our clinic walls and beyond our own capabilities and competences. Meeting the needs of our clinical populations through primary prevention requires building a network of individuals representing the community, the private and public health sectors, and non–health sector agencies. Population health frameworks can facilitate the identification of potential collaborators within and outside the health sector, and inform the design, implementation, and evaluation of integrated services, programs, and policies.49
Underlying many contemporary population health frameworks is a life course perspective, reminding us that time is also a key determinant of health. Both the timing of exposures and the accumulation of exposures over time influence short- and long-term health. Examples of such frameworks applied by physical therapists in the areas of prevention and health promotion include the Life Course Health Development framework, and the Life Stage, Health, and Wellness framework. The Life Course Health Development framework has been applied in pediatric settings to encourage future planning for individuals with neurodevelopmental disabilities, and promote coordinated and continuous care for these individuals during critical periods (eg, infancy and early childhood) and transitions (eg, adolescence to adulthood), and between service systems (eg, health, educational, social).50 The Life Stage, Health, and Wellness model for physical therapy, suggested by Sullivan and colleagues,51 proposes the use of a life course perspective to promote physical activity across the lifespan, and to identify risk factors for poor physical health that indicate a need for physical therapist services. Sullivan et al further argue that physical therapists are well suited to promote health in infancy and childhood by supporting the creation of social and physical environments that encourage motor development and lifelong physical activity.51 Into adulthood, the skills and knowledge of physical therapists can be applied to maximize employability and productivity, both critical drivers of health and subjective well-being.52 Toward the end of the life span, physical therapists can promote health in older adults by working to reduce unintentional injuries, encourage safe mobility, and support independent living.51 Such an approach leverages existing strengths of physical therapists in the assessment and amelioration of movement system deficits, and requires additional consideration of the social structuring of risk and protective factors (which current practices do not readily support).
Research
In addition to guiding clinical practice, population health frameworks can serve to inform physical therapist research. Population health frameworks guide the development of conceptual models that can be systematically tested to establish the nature, strength, and directionality of the relations between health outcomes, various multiple determinants of health, and time. These models are needed to explore the relative contribution of various factors to a particular health outcome and to examine the proportion of cases that could be prevented had a risk factor (eg, obesity) been removed or a protective factor (physical therapist services) been available. Such knowledge is critical in seeking to establish and promote high-value physical therapist services (defined as patient health outcomes per dollar spent), improve service efficiency, and optimize the allocation of scarce resources.
As alluded to previously, there is a general lack of consideration and operationalization of behavioral, social, and environmental health determinants when it comes to monitoring the health of our populations. Researchers, clinicians, and clients, using population health frameworks as a guide, ought to work together to develop a more holistic set of indicators that accurately reflect population health priorities and key health determinants, and establish data linkages across payer and service systems over the life course. Access to such rich data vis-à-vis clinical databases or patient registries would enhance our profession's ability to contribute toward improving population health, and demonstrate our value in rapidly evolving health care landscapes.
Equipped with comprehensive, population-level data, researchers could further leverage population health frameworks to identify health disparities, explore the mechanisms underlying such disparities, and inform the development of quality improvement initiatives or community-based interventions to address these disparities.53–55 In addition, population health frameworks could aid in identifying the differential effects of interventions and programs across populations and among subgroups within a population. 56 The last decade has given rise to large-scale genome studies and precision medicine initiatives as a means of improving population health by “providing the right treatment to the right patient at the right time.” The application of this maxim in physical therapist practice as “precision physical therapy” is certainly appealing.57 Skeptics of precision medicine fear that a disproportionate amount of time and energy will be spent on genetic, biological, or disease processes, while neglecting behavioral, social, and environmental determinants of health. The success of precision medicine (or precision physical therapy) in improving individualized care will require a population-based approach to inform the development of robust prediction models, guide the collection of meaningful population-based data, and guard against selection bias.58
Education
Our profession is beginning to recognize the limitations of condition-based, episodic interventions for individuals, particularly when it comes to the management of chronic, lifestyle-related conditions and their sequelae. As health care professionals, physical therapists have a responsibility to help prevent chronic conditions and disability, improve the overall health of society, and limit avoidable health care costs.15,18,19 The leading causes of worldwide mortality and morbidity have been directly linked to health behaviors, and indirectly linked to underlying social and physical environments. Key health behaviors include sedentary lifestyles, poor nutrition, chronic stress, tobacco use, alcohol and/or substance abuse, unintentional injuries, and poor sleep hygiene. Physical therapists ought to be equipped with the knowledge and skills needed to screen for risky health behaviors in clinic- and community-based settings, provide general health counseling and physical therapist services as required, and recommend appropriate referrals as needed. Participants of multiple physical therapy summits on global health acknowledge the need for prevention and health promotion across practice settings, and advocate for the development of competencies in these areas that are taught in parallel with other clinical skills.18,19 The World Confederation for Physical Therapy and many of its member organizations have outlined broad recommendations regarding the provision of prevention and health promotion services by physical therapists,59 yet these guidelines lack standardization and specificity. Using epidemiological evidence informed by population health, Dean et al60 outlined the theoretical and practical content that is required for entry-level physical therapists in the area of prevention and health promotion, and proposed minimum competencies in these areas.60 We must work quickly and efficiently to further guide the development of entry-level competencies in the prevention and management of NCDs, and in the promotion of individual and population health.
As noted previously, behavioral, social, and environmental determinants are the strongest predictors of population health, yet access to quality health care and rehabilitation services is a critical determinant of health for many individuals. In response, physical therapist students (and clinicians) from many high-income countries provide pro bono services in low-resourced areas primarily through student-led pro bono clinics or medical missions. These efforts, like narrowly defined views of physical therapist practice, tend to be dominated by condition-specific, episodic interventions focused on short-term, functional gains among individuals. We would argue that providing charitable pro bono services in underserved areas, without recognizing and working to ameliorate the root causes of poor health and limited access within the community, perpetuates health inequities.
In Pedagogy of the Oppressed, Paulo Freire argues that the simple donation of resources to historically marginalized and oppressed groups sustains inequality.61 In contrast, true generosity involves standing in solidarity alongside marginalized groups to ameliorate the root causes of health inequities (eg, poverty, discrimination). Don Berwick, former President of the Institute for Healthcare Improvement and Administrator for the Centers for Medicare and Medicaid Services, argues that we must work not only to cure diseases, but to cure injustice. Our professional organizations further call upon us to confront health inequities through advocacy and the creation of health-promoting environments.19,62,63 The Centers for Disease Control and Prevention and WHO outline a number of strategies for advancing health equity alongside community members.28,64 In our opinion, the ultimate goal of pro bono clinics should be the (re)integration of clients into existing health systems and the elimination of the root causes of health inequities.65 For this to happen, clinical services need to align with community needs, and programs ought to foster strong collaborations with community members and non–health sector partners (eg, education, housing, employment, and transportation).65 Population60 health frameworks can inform the work of physical therapists by helping us to better understand the root causes underlying health inequities in our local communities, and identify key stakeholders with whom to collaborate.49
Conclusion
Health is a reflection of where we live, work, learn, and play. To remain relevant and maximize our skills in dynamic health care landscapes, we must enhance our profession's capacity to better understand and address factors beyond the individual and the health care system that influence one's opportunity to lead a healthy life. We propose adopting population health frameworks in physical therapist practice, research, and education to help identify systematic variations in health outcomes and their related determinants, inform the development of programs and policies that improve the health and well-being of populations, and ameliorate disparities wherever they exist. Such population-based approaches should be viewed as a complement to more traditional, individualized approaches to care rather than a replacement. This is a critical time for the physical therapist profession to embrace the concept of population health, and our potential role in transforming the health of society.
Author Contributions and Acknowledgments
Concept/idea/research design: D.M. Magnusson, M. Eisenhart, I. Gorman, V.K. Kennedy, T.E. Davenport
Writing: D.M. Magnusson, M. Eisenhart, I. Gorman, T.E. Davenport
Project management: D.M. Magnusson
Consultation (including review of manuscript before submitting): M. Eisenhart, I. Gorman, V.K. Kennedy, T.E. Davenport
The authors would like to thank HPA-The Catalyst, the Global Health Special Interest Group, and the Foundation for Physical Therapy for their support of programming and research in the area of population health sciences.
Funding
There are no funders to report for this submission.
Disclosure
The authors completed the ICJME Form for Disclosure of Potential Conflicts of Interest and reported no conflicts of interest.
References
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