Functioning

Jerome Bickenbach, University of Lucerne (Switzerland), defined functioning as “information about how a person’s health state affects their daily life…information that describes the actual lived experience of health” (Bickenbach et al., 2023). He explained that functioning comprises the domains of both biological health (with biophysical information about bodily functions and structures) and lived health (with information about actual performance), where lived health is fully contextualized as an outcome of interactions between a person’s intrinsic health capacity and features of their environment (Bickenbach et al., 2023; Stucki and Bickenbach, 2017, 2019). According to Bickenbach, functioning “accounts for the value of health because it tells us that health matters to us because it improves what matters to us, namely what we can do. It explains behaviors, why we move toward seeking health care. It allows us to predict future health needs in terms of what people’s aspirations for what they want.” He added that functioning also helps make sense of disability in a way that fully comprehends the experience, as a limitation in functioning in the person’s environment. Alarcos Cieza, WHO (Switzerland), explained that functioning can be categorized by our body functions and structures (e.g., pain, muscle weakness), our activities (e.g., self-care, walking), and our participation (e.g., going to work or school). Matilde Leonardi, Fondazione IRCCS Istituto Nuerologico “Carlo Besta” (Italy), said that describing functioning is like describing the wetness of water in that the whole is obvious—how a person’s health state affects their daily life—but the components (i.e., hydrogen and oxygen) by themselves do not explain the experience. Functioning is more than just the sum of its parts, but a comprehensive experience. She advocated for the initial definition of functioning as operationalizing health using a biopsychosocial model, with recognition that biological, psychological, and social factors interact and can affect functioning through different policies, systems, and services.⁴

WHO’s International Classification of Functioning, Disability and Health

Several participants discussed using WHO’s International Classification of Functioning, Disability and Health (ICF) to operationalize functioning in health systems and to build an evidence base for investing in functioning and for identifying effective interventions. Bickenbach said the ICF is designed to measure and compare differences in health, enabling functioning to serve as a third indicator of health, alongside mortality and morbidity.⁵ The environmental, contextual, and personal factors that influence a person’s functioning were discussed in depth (see Figure 1). Several presenters also referred to the discussion in a study by Bickenbach and colleagues (2023) of how functioning aligns with all six of the WHO’s health system building blocks (see Figure 2). John Beard, Columbia University (United States) and previously director of the WHO Department of Ageing and Life Course, noted that the ICF has been revolutionary in the field of aging.

FIGURE 1

World Health Organization’s model for the International Classification of Functioning, Disability and Health. NOTES: Contextual factors include environmental factors and personal factors. Environmental factors make up the physical, social, and (more...)

FIGURE 2

Highlights for implementing human functioning within health systems. NOTE: ICF = International Classification of Functioning, Disability and Health. SOURCES: Presented by Francesca Gimigliano, University of Campania, February 16, 2024. Bickenbach et al., (more...)

Healthy Longevity and Aging

John Beard explained that the NAM Global Roadmap for Healthy Longevity defined healthy longevity as the state in which years in good health approach the biological lifespan, with physical, cognitive, and social functioning that enables well-being across populations (NASEM, 2022). He added that healthy aging is “not only lengthening the lifespan, but also extending the health span, allowing individuals to live high-quality, productive lives well into the later years.”

Rehabilitation

Paola Sillitti, Organisation for Economic Co-operation and Development (OECD) (France), noted that rehabilitation is “sometimes a blurry term that includes many different types of services,” including physical therapy, occupational therapy, speech and language therapy, cognitive therapy, and mental health therapy, and can be accessed in a variety of settings. Alarcos Cieza shared the WHO’s definition of rehabilitation as “a set of interventions designed to optimize functioning and reduce disability in individuals with health conditions in interaction with their environment” (WHO, 2023b). In her presentation, Francesca Gimigliano, University of Campania “Luigi Vanvitelli” (Italy), added that the definition of rehabilitation for research purposes is a “multimodal, person-centered, collaborative process including interventions targeting a person’s capacity and/or contextual factors related to performance, with the goal of optimizing the functioning of persons with health conditions currently experiencing disability or likely to experience disability, or persons with disability” (Negrini et al., 2022). Throughout the workshop, participants and presenters discussed—and sometimes disagreed about—to what extent rehabilitation should occur primarily in clinical practice (responding to a particular medical condition) or within a public health agenda.

Disability-Adjusted Life Years

Researchers often use disability-adjusted life years (DALYs) to measure functioning in a public health or economic context (see Figure 3). Abderrazak Hajjioui, Abdelmalek Essaâdi University (Morocco), noted that the rehabilitation community can aim to improve the years lived with a disability, which can be reframed as “years lived without functioning, without quality of life, without well-being” for advocacy purposes. The use of DALYs and similar proxies was discussed at length, as was the need for more direct forms of measurement. For instance, Jan Reinhardt, Sichuan University (China), commented that DALYs and similar units, which are often used to quantify burden of disease, rely on a “concept of disability that has absolutely nothing to do with how we see . . . and define” disability. Nonetheless, Carl Willers, Karolinska Institutet (Sweden), noted that such measures are currently used to build the case for investing in functioning and rehabilitation.

FIGURE 3

Disability-adjusted life years. NOTE: DALY = disability-adjusted life years; RIP = rest in peace (referring to death). SOURCES: Presented by Abderrazak Hajjioui, February 16, 2024. Shah et al., 2019; originally adapted and reproduced through an Open Government (more...)

The Functioning Revolution

Jerome Bickenbach posited that while “we’ve been speaking in functioning all of our lives,” its significance to our health and well-being is underappreciated and underacknowledged. He noted that the experience of health and what it means to a person to live with a condition is missing from society’s concept and picture of health, which focuses solely on longevity, mortality, and morbidity. He used a personal example of how his foot joint pain is medically defined as concentrated urea crystals in his joint, which, while being important information, is an abstraction because it doesn’t communicate the pain felt when walking. The condition affects how he moves through the world, which affects whether he achieves or fails to achieve what he wants to accomplish. He asserted that being able to achieve our goals and aspirations is why health matters to us.

Bickenbach stated that health systems need to be reoriented from assessing and addressing mortality and morbidity to assessing and addressing the experience of health conditions—that is, functioning. Doing so, he argued, would fulfill the United Nations (UN) Sustainable Development Goal 3: to ensure healthy lives and promote well-being for all at all ages. This goal implies a link between health and well-being, he continued; why does improving health improve well-being? “Well,” he said, “living a long life is a good thing . . . but you can live a long life in utter misery.”

Bickenbach pointed out that, while the idea of well-being is very simple (“being able to do and become what you wish”), multiple factors adversely affect well-being, like poverty, discrimination, and migration. Health, he added, can also be a barrier. Bickenbach explained that the International Classification of Diseases (ICD) is a way to categorize information about disease and morbidity in an internationally comparable, standardized way. The ICD allows researchers to collect information that contributes to the understanding of what health services are being provided—and, more importantly, he said, how those services can change outcomes. But the ICD does not enable data collection on what it is like to live with the conditions it describes; “we need to know what it’s like to live those conditions,” he stated.

Early on, said Bickenbach, the ICF was characterized as a complement to the ICD, to provide more comprehensive data collection for research. But the ICF was also intended “to capture something which had been missing in our understanding of health,” he explained, to measure differences in health states and identify the impact of interventions. He said that morbidity and mortality are indicators of health, but “the space in which you live [health conditions] out,” required a third, complementary indicator (Stucki and Bickenbach, 2017). “We use the term functioning for this space,” Bickenbach stated, which identifies classifications of body functions and structures, as well as activities and participation.

According to Bickenbach, the major conceptual revolution is that functioning reveals the lived experience of health, and environmental factors shape and determine that experience as much as the biophysiological changes that occur with a morbidity. Two people experiencing the same condition but in different environments experience different functioning, he continued. Two people suffering knee arthritis, as he does, who are in different environments, will experience qualitatively and quantitively different functioning: “It’s a different phenomenon to struggle to walk through snow uphill” than on flat ground, he explained. The environmental context, Bickenbach said, is a complex interplay of several factors made up of not only the physical elements of the environment (e.g., air quality, air pollution levels, altitude) but also human-built structures that can contribute to or interfere with health. Environment may also include assistance that mitigates such difficulties, interpersonal interactions, and social structures and legal systems.

Bickenbach clarified the relationship between intrinsic capacity and performance, emphasizing that distinguishing between these two concepts is central to the revolution of functioning and the theory of the ICF. Intrinsic health capacity, he said, is an abstraction of what we understand biophysiologically: information about the state of the body, expressed by functions and structures of basic biological components, known as biological health. This capacity is then translated and mediated through the environment, “which can contribute positively or negatively to an experience,” resulting in the lived experience of a health condition, or functioning. Information about functioning, Bickenbach said, includes both the biophysiological state (intrinsic capacity) and its effect on a person’s engaging in activities in their environment (performance), which describes information about how the state of the body affects all of the activities that a person actually engages in their actual environment. He asserted that the lens of performance offers tools for changing environments, medications, and assistive technology. Disentangling capacity from performance enables a clearer understanding of what health services can offer when a person is facing diminished capacity, he said.

Bickenbach then discussed how the functioning revolution applies not only to population aging but also to noncommunicable chronic diseases. He noted that the most salient indicator of a chronic health condition is stable or progressive decline in capacity, with low chances for improvement. But even with reduced capacity, there are tools to improve performance, such as changing environments to make them more accessible, modifying medications, and using assistive technologies.

Bickenbach said that functioning is the “basis for conceptualizing health itself.” It links varying perspectives on capacity and provides a platform for operationalizing health, he explained. It also provides a way to measure improvement before and after an intervention. Functioning is revolutionary, asserted Bickenbach, because it shifts “the center of gravity” of health sciences. He concluded his presentation by adding that “a functioning-based approach to health sciences is a revolutionary way of entering into the domain and rearranging, coordinating, disentangling, and re-reconciling the health sciences in something which could literally be the first legitimate approach to interdisciplinary health research.”

Healthy Longevity

John Beard described how recent changes in health sciences can influence and shift the global approach to aging and how functioning might be framed in the future. First, he mentioned the developing field of geroscience, which takes a biological perspective on aging. Second, he pointed out that an understanding of complex systems (e.g., related to climate change) has advanced, exposing the reality that change is often nonlinear and needs to be understood holistically. Third, he said, computational mechanisms, including machine learning, are enabling analysis of the “complex, dynamic biological changes that occur with age.”

Beard asserted that this shift away from the traditional model, which waits for conditions to manifest before responding, has led to a tipping point in the field. He stated prevalence of chronic disease tends to increase with age and that “aging is the biggest risk factor for almost all of those chronic diseases, far more important than our behavior or other risk factors,” but that “we’re identifying the health changes very, very late.” If clinicians wait until symptoms associated with a chronic condition manifest, the best option is to limit progress of the condition, he explained. Although most people over age 65 are managing complex chronic morbidities, Beard continued, it is becoming possible to identify conditions earlier, before crossing the symptom threshold, so that the chronic disease does not develop or is delayed until much later in life. Functioning declines long after the onset of biological and phenotypical deterioration, he said, due to the body’s ability to compensate.

Beard stated that the 2015 WHO World Report on Ageing and Health “framed healthy aging around the functional ability to be and do” what people value to foster well-being (WHO, 2015). People value feeling safe, having a place to live, having access to healthy nutrition, and being in a walkable and safe environment. Older adults also want to learn, grow, be mobile, and retain autonomy “to their last breath, if possible,” he said, and importantly, older adults want to have relationships and contribute to society, and to be acknowledged. Being able to achieve this well-being relies on both the individual’s health state and their physical and social environment, he said.

Adding to Bickenbach’s discussion of capacity as an abstraction, Beard said that WHO’s idea of intrinsic capacity includes all the individual-level attributes that contribute to ability. Capacity grows and develops over the life course, he said, then reaches a peak and declines gradually. The second half of life includes a significant range of capacity, said Beard, and the tendency to box older adults into one group of those age 65 and older is incorrect, as “one of the great hallmarks of aging is heterogeneity.”

Beard emphasized that segmenting the population into groups enables appropriate policy responses to help them “build and maintain the highest possible level of capacity” (see Figure 4). This approach formed the basis for the UN Decade of Healthy Ageing, spanning 2021 to 2030, with four priority areas: (1) combating ageism and “changing the way we think, feel, and act about aging and older people”; (2) changing the built environment to allow people to experience aging positively; (3) reframing health systems to address chronic complex conditions that tend to accompany older age; and (4) ensuring access for all to health care and other forms of support.

FIGURE 4

Life course opportunities for intervention. SOURCE: Presented by John Beard, February 16, 2024. Beard et al., forthcoming.

Beard described WHO’s Integrated Care for Older People (ICOPE) approach as being functioning-based (WHO, 2019). Using a model similar to that of pediatrics, ICOPE compares an individual’s functional trajectory with population means. ICOPE’s entry point is screening for functioning rather than disease, and if an individual screens below a certain level, they receive more in-depth assessment and an integrative care pathway. Beard reported that ICOPE is being scaled up in several places, such as in France.⁶

In order to make the concept of intrinsic capacity more concrete, Beard said that five subdomains of capacity (cognitive, sensory, locomotor, vitality, and psychological) can be assessed using common indicators, such as recall and verbal with cognitive capacity, or vision and hearing with sensory capacity. He cited two studies that reveal the power of capacity at predicting outcomes. One study from England demonstrated that after accounting for factors such as gender, age, education level, wealth, and multimorbidities, intrinsic capacity strongly predicted the subsequent development of care dependence (Beard et al., 2019). Another in China showed similar associations (Beard et al., 2022). He linked the vitality subdomain specifically to potentially capturing the underlying biological changes that are the focus of geroscience, suggesting these biological changes ultimately become expressed as more overt capacities and provide resilience to allow people to recover from external stressors.

Beard discussed the Study of Health, Ageing and Retirement in Europe,⁷ which revealed that people of lower socioeconomic status experience worse capacity as they age compared with those of higher socioeconomic status, and that those who need resources the most have the least access to them. Additionally, this study found vast differences among European countries in declines in capacity, indicating the role of environment and the mutability of these effects (Arokiasamy et al., 2015). Beard then examined the English Longitudinal Study of Ageing,⁸ which looked at intrinsic capacity in four cohorts and found that more recent cohorts had slower reductions in capacity and that people are entering older age at higher capacities (mainly because they gained higher capacities earlier in life; Beard et al., 2019).

Beard discussed the National Academy of Medicine’s Global Roadmap for Healthy Longevity (NASEM, 2022), which defines healthy longevity as “when the health span equals the lifespan.” Although people are surviving diseases and thereby living longer, they often have more or more severe chronic conditions, he said; for example, people can survive a heart attack but still live with chronic heart disease. Beard closed by saying, “Now is the time to start thinking about how we can actually move forward and embrace all of these dramatic changes” in other fields and “reframe the way we think about aging and health.”

Rehabilitation in Health Systems: The Time Is Now

Alarcos Cieza discussed the World Health Assembly’s recent adoption of the WHO resolution on rehabilitation in health systems and emphasized how three factors contributed to the resolution: conceptual clarity on rehabilitation; stakeholder cohesion; and support from individuals, countries, institutions, and organizations for the rehabilitation agenda. Cieza said the resolution focuses on ways that rehabilitation is fundamental for strengthening health systems with a political mandate, normative weight, and moral value. Box 2 summarizes Cieza’s overview of the resolution’s key components.

BOX 2

World Health Assembly Resolution 76.6 on Strengthening Rehabilitation in Health Systems: An Overview.

Conceptually, rehabilitation is about optimizing a person’s level of functioning, Cieza said, and how interventions seek to reduce disability and work with people’s environments toward optimal functioning. A key component of the WHO resolution was to support equity and improve access to high-quality rehabilitation services, she noted. Less than 50 percent of those who could benefit from rehabilitation services have access to them (Cieza et al., 2021). The only mechanism for achieving equity, she declared, is ensuring that rehabilitation services are part of universal health care coverage through the strengthening of health systems so that people can receive needed services without facing financial hardship. She added that rehabilitation services should be integrated not only in specialized centers but also at the secondary, tertiary, and community levels to ensure comprehensive coverage and access.

Cieza explained that the resolution required “stakeholders’ cohesion,” which was garnered through the Rehabilitation 2030 initiative.⁹ These efforts included producing evidence, such as the 2019 Global Burden of Disease Study, which reported that 2.4 billion people globally experience a health condition that could benefit from rehabilitation (Cieza et al. 2021). This figure increased by 63 percent in 30 years, driven by the aging population. Cieza also mentioned a special issue of the WHO Bulletin on advancing rehabilitation through health policy and systems research (WHO, 2022b) and the guidebook Clinical Management of COVID-19 (WHO, 2023c), which showed that rehabilitation is essential for the clinical management of infectious diseases, as well as other conditions. Through Rehabilitation 2030, Cieza said, WHO also developed technical tools for strengthening health systems, such as the Package of Interventions for Rehabilitation.¹⁰ Cieza reported that WHO worked for 3 years with 725 rehabilitation experts from all 6 WHO regions to create these technical tools, and these efforts contributed substantially to stakeholder cohesion.

Finally, Cieza explained, passing the resolution required the work of “champions.” She said that these included individuals (many of whom participated in this workshop), academic institutions, organizations such as nongovernmental organizations and foundations, and WHO member states. In closing, Cieza invited participants to study the resolution and also challenged participants to use the resolution to inform their deliberations throughout the workshop and beyond.

Operationalizing Functioning for Population Health

Francesca Gimigliano explained that rehabilitation is key to optimizing functioning. She discussed the importance of contextualizing functioning and presented different tools and methods in operationalizing functioning and rehabilitation in health care settings. Understanding a person’s functioning in context is key, said Gimigliano. She illustrated why context matters with an example of astronauts, who often have very high intrinsic capacity on Earth but limited capacity in a different environment like the moon.

Gimigliano noted that although there are differing definitions of rehabilitation, functioning is a critical aspect of rehabilitation. She outlined several tools to describe the building blocks of integrating functioning across health systems, including the International Classification of Service Organization in Rehabilitation,¹¹ the Individual Rehabilitation Project,¹² the Scheda di Dimissione Ospedaliera in Riabilitazione,¹³ Standardized Assessment and Reporting System for functioning information,¹⁴ the WHO’s Model Disability Survey,¹⁵ and the International Society of Physical and Rehabilitation Medicine’s Clinical Functioning Information Tool (ClinFIT).¹⁶

Gimigliano said that key to functioning as it relates to the ICF is participation or performance, which is “the ultimate goal of rehabilitation.” She suggested that advancing technologies such as the Metaverse could enable individuals to return to participation in new way (Calabrò et al., 2022). She concluded that “functioning really depends on the timing, on the context, on the place, and on everything that is around us.”

Role of Functioning in Healthy Longevity Research

Eleanor Simonsick, National Institute on Aging (United States), discussed three areas of functioning in healthy longevity research: hands-on functional performance testing, functional assessment, and assessing age-appropriate metrics of success. She stated that functional performance assessments are essential as many individuals are unaware of their capacities and limitations; functional performance testing is just the beginning as the behaviors and health conditions that underly or contribute to deficient performance are vast; and functional performance testing should tap capacities as well as limitations, with evaluation criteria accounting for age, sex, and size.

She explained that many people are unaware of their limitations or may underreport the severity of their impairments, so performance tests can provide a more accurate assessment of functioning. Simonsick described the Health, Aging and Body Composition Study,¹⁷ which evaluated older adults who reported no difficulty with walking a quarter mile (or 400 meters), climbing a flight of stairs, or activities of daily living using an objective walking test covering 400 meters. Participants were first assessed by phone, and eligible participants received a secondary assessment during a home visit. Following these two assessments, nearly 400 participants, or 12 percent, were excluded from the walking test due to health-related exclusion criteria (e.g., an electrocardiogram abnormality), and 356 participants could not complete the test because of an overly elevated heart rate, chest or leg pain, shortness of breath, or excessive fatigue. Stoppage or exclusion from the test predicted walking difficulty two and a half years later. Walking test performance also predicted cardiac outcomes and mortality (Newman et al., 2003).

Next, Simonsick explained that functional assessment is like a curtained window to health and aging, in that while functional performance testing can reveal limitations, it does not necessarily reveal the underlying causes (i.e., what is on the other side of the window). The Lifestyle Interventions and Independence for Elders Study sought to understand whether structured physical activity could delay onset of disability for people on the cusp of mobility disability and found statistically significant but nonetheless weak differences between the intervention and control groups.¹⁸ In addition to an overall weak impact of the mobility intervention, Simonsick noted that around 60 percent of the 800 total participants went on medical leave at least once, and 25 percent went on medical leave at least twice during the study period (Pahor et al., 2006). Simonsick also shared the study results within selected population subgroups, noting that the activity intervention was not successful in those with cardiovascular disease, as it did not address the likely underlying cause(s) or provide appropriate rehabilitation services. Likewise, individuals exhibiting mild cognitive impairment also did not derive benefit from the activity intervention as it did not target cognitive challenges.

Simonsick concluded her presentation by discussing the “tyranny of low expectations” and stressed the importance of including age-appropriate metrics of success alongside indicators of failure. Simonsick illustrated this point by highlighting several longitudinal cohort studies on sarcopenia—age-related loss of muscle mass and strength—which has been evaluated using grip strength, chair stand performance, and gait speed (Cleveland Clinic, 2022). Simonsick used an article providing normative data from 12 studies of British participants to illustrate that men and women ages 60–65 with grip strength below the fifth, tenth, or fifteenth percentile for their sex and age group do not meet age-agnostic criteria for sarcopenia (Dodds et al., 2014), whereas high proportions of those older than 80 performing in the 75th percentile for their age would be deemed sarcopenic. Simonsick emphasized that in a resource-limited environment, young-old individuals performing well below their age-peers and just beginning to decline may derive more benefit from active rehabilitation than individuals in their nineties performing well relative to their peers.

Monitoring Functioning for Health Systems: Lessons Learned

Alan Jette, Boston University (United States), shared lessons he has learned when working with health systems to monitor patients’ functioning throughout the episode of care. Jette reiterated the importance of conceptual clarity and said that monitoring functioning should be done at the level of an individual’s performance of activities, which can help researchers and clinicians describe, measure, and explain the interaction between an individual’s biological health and the environment. He argued that both capacity and actual daily life performance are important because they provide different information and emphasized that when discussing functioning, a focus on an individual’s behavior in an environmental context, not on body systems and organs, is necessary.

Jette said a key lesson is being very selective in what health systems monitor, as too much detail may not be useful. Rather than a universal core set of functions, he said that health systems should focus on monitoring selective functions that reflect the system context for a specific purpose or application. Jette also emphasized the importance of collaborating with health systems, clinician and patient groups, and content and health system experts. Partnerships with these groups have changed the way functioning is monitored in health systems.

The next lesson, Jette said, is accepting and adopting contemporary approaches and tools. Classically, monitoring functioning used a set of fixed items regardless of their appropriateness to a particular patient (e.g., the Functional Independence Measure). And while many instruments for measuring functioning are available and can be useful, most are setting-specific, generate different scores, cannot be compared easily, and need many items or instruments to cover all relevant functional outcomes, which can be burdensome. Newer approaches include the Item Response Theory,¹⁹ a group of measurement models where outcome scores are item-based rather than test-based and scored on probability models. This enables quantitative measuring of functioning and leaves behind traditional ordinal scores. Another innovation is computerized adaptive testing (CAT),²⁰ which can integrate Item Response Theory efficiently on large scales using an algorithm that selects a functional item based on a patient’s previous response. Jette said his work using CAT in the Activity Measure for Post-acute Care²¹ can be completed by either clinicians or patients and is sensitive to clinically meaningful change.

Finally, Jette said, function monitoring needs to be adaptable and simple. For example, colleagues from the Cleveland Clinic asked for an adaptation of Activity Measure for Post-acute Care that did not include CAT, which was impractical for their health system. In simplifying the instrument, the team was able to use Item Response Theory to track selected items that improved decision making in referrals and discharge planning. Jette’s team also developed short-form tests without CAT technology, versions of which are being used by more than 1,000 health care institutions in the United States.

Panel Discussion

In response to Jette’s call for conceptual clarity, John Beard suggested that there is a philosophical difference between the current approaches toward aging science and clinical rehabilitation. The latter tends to measure and restore significant losses, he said, whereas the field of aging science seeks to identify and prevent incremental changes early on. Gerold Stucki expressed his worry that different approaches to rehabilitation and aging may divide the world, commenting that rehabilitation is a health strategy for improvement in all settings, not just clinical. Jan Reinhardt noted that the environmental setting is important when considering measurement, as capacity and performance may differ based on the presence of facilitators or supports. Jette responded that conceptually, the capacity to function is different than actual functional behavior or daily life performance. Fary Khan, University of Melbourne (Australia), mentioned that for older adults, it is often not a single impairment but cumulative and multiple deficits that lead to functional decline, citing research with individuals with multiple sclerosis.

Reflections on Operationalizing Measurement of Functioning

On the second day of the workshop, a breakout group composed of the first panel’s speakers and other workshop participants discussed how to advance functioning measurement.²² Chatterji reported on the group’s discussion on two aspects of measurement: (1) monitoring population health using functioning, as well as whether health interventions are improving population health and disease burden, and (2) creating measures that improve clinical management of patients, with implications for both clinical epidemiology and the impact of interventions. He highlighted the need for matching patients’ profiles with specific interventions to improve outcomes and co-effectiveness.

In discussing future action, Chatterji stated that a clear research agenda identifying priorities and milestones for the next 5 years is needed. Additionally, referencing implementation of functioning measures within national health information systems would demonstrate proof of concept. Chatterji asserted that because burden of disease is important to the public health agenda, collaboration with those involved in measuring disease burden is critical, with the hope of potentially shifting their thinking as it relates to measurement. Collaboration is also needed, he said, with research funders, patient associations, and philanthropies.

Other members of the breakout group discussed stratifying the population by risk and other factors to enable early identification and targeted interventions. The group also discussed how to study the two-way relationship between determinants of health and functioning; monitoring functioning over time to assess cohort effects, rates of decline, and impact of interventions; and examining factors that determine older adults’ functional capacities compared to actual functional performance.

In response to Chatterji’s report on measuring functioning at the population level, Beard commented on the need for direct measures of functioning, stating that DALYs (see Figure 3) and healthy life expectancy are indirect measures. He expressed concern that overlaying aging with functioning will promote ageism, sharing the example that measuring workforce participation does not apply equally to all. An impoverished older person who has lost significant capacity through years of heavy work may continue to participate in the workforce out of necessity, not because they are healthy.

Matilde Leonardi suggested that the 5-year plan could call for studies on risk factors and determinants of health because these factors are modifiable. Chatterji replied that “we have to pick our battles here”; making the case that burden of disease is an inadequate measure and demonstrating the feasibility of direct measurement of functioning in the population would be immense progress, he asserted. Walter Frontera commented on the need to develop tools for collecting data and making the economic case for investment in functioning and rehabilitation. Chatterji replied that numerous tools are available (e.g., ClinFIT and ICF Standardized Assessment and Report System), but domains need to be identified that span from patients in a clinical setting to healthy individuals in a community.

Measuring and Enhancing Functioning in Health Systems

Paola Sillitti presented the importance of measuring what matters to people by gathering data on their health, well-being, and functioning, and on how to build the economic case for rehabilitation. In 2021, OECD countries spent an average of 15 percent of their budget on health (OECD, 2023).²³ Investments in health typically focus on preventing and managing chronic conditions, Sillitti continued. The outcome of these expenditures is that people are living longer: In 2022 the average life expectancy in OECD countries was approximately 80 years, which is up from around 68 years in 1960 and 77 years at the turn of the century (OECD, 2023). Preliminary data from the OECD Patient-Reported Indicator Surveys also showed that people’s rating of their health depended more on the number of chronic conditions they were facing than on their age (OECD, 2023).

Historically, researchers first focused on measuring mortality and life expectancy, then moved toward understanding levels of disability and now toward measuring well-being. There is growing interest in measuring what really matters to people, though gathering such data is challenging, she explained. Since 2017 the Patient-Reported Indicator Surveys initiative has sought to center people’s needs and preferences in health systems performance assessment, which is at the core of OECD’s new framework (OECD, 2024; see Figure 5).

FIGURE 5

Health system performance assessment framework by the Organisation for Economic Co-operation and Development. SOURCES: Presented by Paola Sillitti, February 16, 2024. OECD, 2024.

Sillitti continued by stating that investments in health are necessary for curative care, as well as preventing and managing chronic conditions and supporting functioning. Rehabilitation is an important component of these objectives, and rehabilitation services are available in 86 percent of OECD countries.²⁴ She added that the evidence base is small but growing for demonstrating the effectiveness of rehabilitation. Some existing evidence shows that rehabilitation might provide both cost benefits and savings. Rehabilitation could also enable older adults to continue contributing to the “economy of well-being,” she said. When people contribute to society, they also contribute to economic advancement, leading to healthier populations with higher levels of well-being. Additionally, rehabilitation supports older adults after they receive acute care, when they are more likely to have accidents and falls—thereby reducing the risk of receiving additional (and costly) acute care, according to some existing evidence. She added that investments are needed to establish a stronger evidence base to demonstrate these benefits of rehabilitation. She concluded her presentation by inviting those interested to review OECD’s work on the Patient-Reported Indicator Surveys initiative and other efforts, such as the Health at a Glance report (OECD, 2023).²⁵

Building Evidence for an Investment Case

Carl Willers discussed the investment case for optimizing functioning for healthy aging and longevity. Because resources are scarce and interventions are costly, defining the indicators for functioning is essential. Health indicators have historically focused on morbidity and mortality and most resources are concentrated on reducing those. But if these indicators are not sufficient to explain individuals’ degree of well-being and if efforts to address these do not correlate with well-being, then resources may be concentrated in areas that are not of the highest priority, he explained. He added that health-related quality of life is traditionally used to indicate the benefit of a given treatment but may differ from actual lived health without accounting for the contributions a person may make to society as a result of reducing burden of disease.

Willers stated that building a case for optimizing functioning will require high-quality data to demonstrate the cost difference in outcomes with new versus old interventions (see Box 3). Additionally, data can show value based on outcomes from an intervention compared with the costs of that intervention. Worldwide, 2.4 billion people would benefit from rehabilitation services (Cieza et al., 2021).²⁶ In the United States, the cost-effectiveness of rehabilitation interventions could save an estimated $15.5 billion annually (Neumann et al., 2014).²⁷ Willers asserted that rehabilitation efforts are needed in many sectors in addition to health care, including the labor market, education, and social affairs and leisure.

BOX 3

Characteristics of Functioning and Cost Data Needed to Build an Investment Case.

Panel Discussion

In response to Willers’s comments on a multisector approach to rehabilitation, Leonardi cautioned that defining functioning broadly may be “deresponsibilizing everyone,” implying inaction because no one in particular bears responsibility to solve the problem. Willers agreed that the multisectoral approach risks diluting the value of rehabilitation and that the first step is building evidence for rehabilitation interventions within health care. However, he said, this does not contradict the need for continued data collection, research, and studies to show ministries of health that investment should occur across all sectors. Sillitti brought up “health in all policies” as a precedent for this approach and said involving other sectors does not necessarily dilute efforts but makes them stronger with more support.

John Beard commented that the Global Burden of Disease does not account for the benefits of rehabilitation; people who are recovering from a disease would still be counted in prevalence data. Willers responded that the aim is to add a functioning perspective to a common unit of measure, such as DALYs. Jerome Bickenbach warned against mixing descriptions (e.g., does a person have deficits?) and assessments of functioning (e.g., do those deficits bother them?) and said that using a description such as DALYs as a proxy for assessment can be confusing. Sillitti replied that the two complement rather than oppose one another, and Willers add that the maxim “don’t let the perfect become the enemy of the better” can be useful, as seeking a perfect indicator or measurement should not conflict with striving for improved tools. Walter Frontera asked whether the rationale built on the OECD data can be applied to low- and middle-income countries (LMICs). Sillitti replied that OECD mainly comprises high- and middle-income countries, but the cost-effectiveness of rehabilitation should apply to LMICs as well.

One workshop attendee asked about the bottleneck in data collection. Willers said, “It’s at least partially a matter of comparability,” and added that using the ICF would enable comparisons across diseases and in other contexts. Stucki agreed, noting that the data may be available and the ICF can be used as a reference system to map the data. Sillitti added that health care research is “data rich but information poor”—in other words, lots of data are available but the tools to interpret them properly are less so. Vanessa Seijas, University of Lucerne (Switzerland), said, “Some people could argue that we have been measuring functioning for a long time,” citing the 36-Item Short-Form Health Survey used in the Nurse Health Survey since 1992, which asks questions such as how conditions limited a person’s ability to perform tasks in the last 4 weeks.²⁸ She asked Willers to comment about the challenges seen so far. Willers responded that two obstacles are the subjectivity of patient-reported data (such as in the 36-Item Short-Form Health Survey) and the need for greater context specificity. Elias Mpofu, University of North Texas (United States), asked whether subjective costs are adequately measured when using cost-effectiveness and utility to demonstrate value. Willers agreed that suffering, pain, and other categories need to be acknowledged and included in the equation.

Reflections on Building the Economic Case for Functioning and Rehabilitation

On the second day of the workshop, Sillitti reported back on the discussion from the breakout group on economics,²⁹ which discussed developing policies that allow people to “live better, improve their well-being,” and that incorporate people’s health, social system, and environment. Because these policies must be evidence driven, the evidence itself needs to be developed, ideally using a learning health system approach, she explained. Sillitti emphasized that economic outcomes need to include affected people’s viewpoints, such as the importance of contributing within their workplace or living independently. Outcome measures need to account for both formal and informal costs, including long-term care and social services. Data collected need to be accessible and interoperable, and they need to reflect the continuum of care across the lifespan and across sectors. These qualities will address the issue of the health care sector being “data rich and information poor,” where data are available but not linked or comparable for use in a meaningful way, she explained.

The participants in this breakout group said that the understanding of conceptual frameworks and measurement instruments for disability, functioning, and well-being need to be clarified as two distinct but complementary things. Additionally, infrastructure needs to be developed to enable standardized reporting of functioning information. Making an investment case includes demonstrating opportunity costs, showing the cost of not investing in rehabilitation across sectors or having adequate access to adequate services, and aligning incentives for those who are financing services and those receiving positive spillovers from implementing services.

Abderrazak Hajjioui commented that the field needs more studies about opportunity costs for LMICs specifically, because while governments in these countries do not need to be convinced that rehabilitation is important, they need to see that these investments affect the gross domestic product. Policymakers may be convinced, he continued, if they see that they are losing money by investing only in acute medicine, especially when patients go home to die of complications. Patricia Morsch, Pan American Health Organization (PAHO) (United States), agreed, saying that disaggregating information can demonstrate the benefits of rehabilitation for older adults because long-term care for these individuals is expensive for countries.

Leonardi commented that instruments are needed for demonstrating that rehabilitation helps to maintain a level of functioning and that without it, functioning levels would worsen. Most measures are designed to show improvement rather than maintaining the same function, she added. Diana Pacheco, University of Lucerne (Switzerland), responded that economists make the case for an intervention by comparing people who have a health condition with members of the general population who have similar characteristics but lack that health condition; this allows for measuring the benefits of maintaining functioning, even if the intervention does not improve functioning. Stucki brought up the need for functioning trajectories that demonstrate how a person’s functioning would be affected without an intervention (a counterfactual), which would enable cost analysis and evaluation of both overall effectiveness and cost-effectiveness.

Rehabilitation as a Strategy for Promoting Healthy Aging

Patricia Morsch presented on ways rehabilitation can serve as an interprofessional and transdisciplinary strategy to support healthy aging and healthy longevity. In PAHO countries, the gap between life expectancy and healthy life expectancy is 12 years (PAHO, n.d.).³⁰ Functioning can be optimized in spite of diminished capacity through appropriate and timely interventions in the health system (e.g., rehabilitation), long-term care, and age-friendly environments (see Figure 6). Morsch added that rehabilitation needs are increasing with age and thus emphasized the importance of having rehabilitation services specifically for older adults, as well as preventive care.

FIGURE 6

Trajectories of healthy aging: Optimizing functional ability. SOURCES: Presented by Patricia Morsch, February 16, 2024. Adapted from WHO. 2021. Decade of healthy ageing: Baseline report. https://www.who.int/publications/i/item/9789240017900 (accessed (more...)

Morsch described PAHO’s ICOPE framework for implementing a strategy for promoting healthy aging (see Figure 7). These guidelines support health professionals at the micro, meso, and macro levels (see Meyer et al., 2014). ICOPE starts with a person’s intrinsic capacity and develops a more in-depth, person-centered plan for evaluation and care, with an emphasis on community engagement. It also involves risk assessment to enable interventions to begin before capacities are lost.

FIGURE 7

Integrated Care for Older People. NOTES: IC = intrinsic capacity; FA = functional ability. SOURCES: Presented by Patricia Morsch, February 16, 2024. Adapted from WHO. 2019. Handbook: Guidance on person-centered assessment and pathways in primary care (more...)

With a focus on functioning, ICOPE can been adapted to the realities of each country where it is implemented. The strategy aims to incorporate functioning in the practices already in place in each country, with a community worker or case manager to integrate the information and help the individual navigate referrals to community services, keeping the emphasis on what is important for each person.

Morsch presented two examples of programs that PAHO has used to implement ICOPE and increase community engagement. The Community Aging in Place Advancing Better Living for Elders program, which is being implemented in the United States, connects older adults with a repair worker, occupational therapist, and nurse to improve functioning.³¹ Through this program, a repair worker might provide adjustments to the patient’s home so that they can remain living there with improved functioning. Initial evidence points to improvements in activities of daily living and reduction in depressive symptoms and home hazards (Szanton et al., 2016). Second, Vivifrail is a 12-week program that prescribes home-based exercise based on results of a functional test, with the goal of improving functional capacity.³² Participants receive a passport book with their exercises, and after 12 weeks, they receive a new passport of exercises tailored to their improvements through the program. Vivifrail is a unique intervention as it allows participants to complete exercises at home and does not require a health care provider or rehabilitation professional.

Prehabilitation, Prevention, and Maintenance for Maximizing Functioning

Fary Khan spoke about the clinician perspective in the Asia-Pacific region,³³ and ongoing work on integrating prevention into rehabilitation (“prehabilitation”) and optimizing functioning in multiple programs. By 2050 an estimated 59 percent of the world’s population of those aged 80 years and older will be living in the Asia-Pacific region (United Nations, 2022).

In Australia, 4.4 million people (18 percent of the population) have a disability (Australian Institute of Health and Welfare, 2022). Rehabilitation service delivery within the public hospital system in Melbourne aims to reduce variation in clinical practice by standardizing community care and reducing the incidence of people returning to the hospital. The health system operates with a hub-and-spoke model, where the rehabilitation clinician connects patients with resources both inside and outside the health care system. She added that longer-term surveillance is critical. The Australasian Rehabilitation Outcomes Centre is the second-largest rehabilitation medicine registry in the world, Khan said, and recently began collecting data on ambulatory care. She shared that there are many opportunities to reduce variation and standardize the community care process, such as leveraging advocacy associations for diagnosed diseases (e.g., the Multiple Sclerosis Society) that develop clinical guidelines, building cohesive team structures and community supports, such as physiotherapists in local gyms who receive specific training for working with those recovering from spinal injuries, and generating timely accessible actional information through electronic medical record and patient journey boards. Community-based organizations provide wellness programming, she said, and options are expanding for integrating technology across the rehabilitation care continuum (e.g., wellness apps, cybernetics, artificial intelligence, and telehealth).

Khan cited several studies demonstrating that prehabilitation can improve health outcomes for high-risk patients during post-operative recovery. Prehabilitation involves meeting with behavioral therapists, physiotherapists, occupational therapists, and others to prepare for recovery from treatments. This strategy provides preventive services for patients with high-level risk factors, or high-risk procedures for lung, colorectal, gastrointestinal cancers, and abdominal surgery (Assouline et al., 2021; Lambert et al., 2021; Rosero et al., 2019; Waterland et al., 2021).

Rehabilitation as a Health Strategy for All Populations

Elias Mpofu discussed how to reorient rehabilitation as a health strategy, and how to see capabilities as opportunities in people’s lives. Capabilities are a means for people to influence what happens in their lives, and by addressing capabilities, rehabilitation can be used as a health strategy to empower healthy aging.

Reorienting approaches to rehabilitation must consider the context of people’s life situations, he explained (see Figure 8). Health systems often focus on symptom relief, or “ameliorative change” (the innermost ring in Figure 8), but that does not account for other domains of a person’s life that impact health status, such as work, family, and education, or their interaction with services. Mpofu also emphasized the impact of health disparities, and how people access and use health services. Preventive care can address not only people’s health conditions but also their life situations by helping them with personal goals and development. He advocated for a social justice approach, with the goal of influencing individuals, the role of social systems in their lives, and society at a broader level.

FIGURE 8

Life situations drive people’s health function. SOURCES: Presented by Elias Mpofu, February 16, 2024. Mpofu, 2024.

Rehabilitation needs to be reimagined as oriented toward the whole life, with a health strategy that includes counseling, stewardship, advocacy, and more (see Figure 9). He referenced work by Stucki and colleagues on this topic (Stucki and Bickenbach, 2017, 2019; Stucki et al., 2019) and added that he believed community public health is the future of aging and functioning.

FIGURE 9

Reimagined whole-life-oriented rehabilitation strategy. SOURCES: Presented by Elias Mpofu, February 16, 2024. Mpofu, 2024.

Panel Discussion

In discussion following the panelists’ presentations, Matilde Leonardi asked about the government or society’s responsibility when people may not have the strength to speak for themselves. Mpofu responded that guardianship issues vary by jurisdiction, and each panelist discussed the benefits of helping people plan ahead (e.g., using advanced care directives), especially when they receive a diagnosis that will likely lead to the inability to speak for themselves in the future.

Keith asked panelists to address the social determinants of physical functioning. Mpofu urged a holistic approach, and not partitioning people according to medical specialties. Morsch said that all stakeholders should be included and that a multisectoral approach will be very helpful. Khan said she’s observed areas with limited economic resources produce “really good outcomes,” and that “it’s really about how you tailor your service delivery to match the needs of the person in the community.” Roxanne Maritz, University of Lucerne (Switzerland), described cutoffs in rehabilitation services in many health systems for those who pass a working age. Given that context, she asked Khan how to sustain rehabilitation services for the aging population. Khan responded that cutting off services in this way is a form of ageism but stated that some health systems, such as Melbourne’s, have rehabilitation services for adults of all ages. Carla Sabariego, University of Lucerne (Switzerland), asked why the term rehabilitation is not included in the ICOPE description or featured in PAHO’s implementation strategies. Morsch replied that rehabilitation is considered part of integrated care. Khan added that “you can’t just box rehabilitation into a tiny area. It’s huge . . . the preventative, the health promotion elements, the prehabilitation elements in the community right through to triaging in the community.” Mpofu agreed, adding that a broader view of rehabilitation is more sustainable and allows for greater empowerment.

Reflections on Developing Health Services for Rehabilitation and Functioning

On the second day of the workshop, Keith presented on the points discussed by the health services breakout group.³⁴ She explained that two major themes emerged from this discussion: (1) physical functioning maintenance and care within the health system and community settings, and (2) early screening assessments for older adults who appear to be functioning normally. Older adults who are functioning normally are not typically screened for changes in functioning or fall risks, but this monitoring is an important opportunity to intervene before extensive health care services are necessary, she explained.

Participants in the breakout group discussed promising areas for the future, including assessment instruments that are consistent across care and community settings, and expanding the availability of prehabilitation and rehabilitation in primary and long-term care, Keith said. Rehabilitation professionals need to be part of an integrated health care team, including in underserved areas, and rehabilitation needs to be person-centered and account for the specific needs of the patient’s physical and social environment, including whether or not they have pre-existing conditions. She added that assistive technologies should also fit the needs of the person.

Marija Glisic, Swiss Paraplegic Research (Switzerland), asked how to address cultural considerations, as decline and death in the older population are to be expected and even doctors have low expectations in some countries. Keith referred to Eleanor Simonsick’s phrase, the “tyranny of low expectations,” and said that “we have to call out [ageism] when we see this in social media and other kinds of popular media, when we hear people disparaging themselves because they’re older adults. That has to all change.”

Seijas agreed that ageism is an issue in the criteria clinicians use to determine whether “a person is worth the effort” of receiving rehabilitation, and said this bias can appear in many areas, including insurance policies. Keith responded that a trio of challenges relate to ageism in rehabilitation: beliefs about whether the patient can do the rehabilitation, beliefs about whether the patient will do the rehabilitation, and the question of whether providers trust facilities enough to refer their patients to them.

Walter Frontera mentioned that almost all of those who would benefit from rehabilitation live at home in their communities, not in rehabilitation units or acute care hospitals. Given this, Leonardi and Keith discussed how to delineate rehabilitation services. Leonardi said that payment systems need to identify which professionals are providing rehabilitation, and Keith emphasized that rehabilitation affects “a multitude of health outcomes, not just body function.”

Harmonizing Research Addressing Functioning

Jonathan Bean, Harvard Medical School (United States), presented on how the aging and geriatrics field responded to the ICF framework, important initiatives in aging and rehabilitation, and ways to harmonize strategies moving forward. The ICF framework was initially met with debate and hesitancy to adopt the model fully in the field of geriatrics and gerontology (Guralnik and Ferrucci, 2009), especially in countries like the United States (Jette, 2009). The primary concerns were that ICF was redefining the concept of disability and that there was a lack of clarity about the border between activities and participation (Freedman, 2009). This ambivalence and sometimes ignorance around applying ICF continues today, said Bean, which is why communicating in a common language is key.

Frailty, defined as a “state of increased vulnerability to stressors caused by decreased physiologic reserves” (Fried et al., 2004, p. 256), is a powerful tool for stratifying older adults and adverse health outcomes. It is relevant for rehabilitation as it addresses the ability to withstand and recover from stress. Bean explained that despite much debate (Costenoble et al., 2021), frailty can be a useful concept for approaches and discussions related to function and disability (Fried et al., 2001; Rockwood et al., 2005).

Bean described two ongoing initiatives to support aging and rehabilitation. The Age-Friendly Health Care Systems Initiative recognizes that given the growing aging population, there are not enough geriatricians to go around.³⁵ The initiative seeks to help non-geriatricians to think like geriatricians and uses the 4Ms Framework to teach best practices for care of older adults in a patient-centered care approach (see Figure 10).

FIGURE 10

The 4Ms Framework. SOURCES: Presented by Jonathan Bean, February 16, 2024. Institute for Health Improvement, n.d.

The Research Treatment Specification System,³⁶ a theoretical framework that can improve research intervention reporting (Van Stan et al., 2019), recognizes the problem of lacking standardization in rehabilitation research. Sometimes referred to as a “black box of rehabilitation,” a lack of standardization in research methods can mean the active ingredients that make an intervention work remain unknown.³⁷ It is important to operationally define the contents of care, Bean continued, so clinicians can understand which approach may be best for their patients. This helps them avoid a “machine gun” approach, where the clinician tries to treat all the different deficits at once, he explained. The Research Treatment Specification System treatment theory focuses on what clinicians can do to support functional change and how they can include the active ingredients needed for rehabilitation treatments to expand the evidence base for those treatments. Treatment theory defines a mechanism of action and the outcomes that are directly linked to that mechanism, which reflects the ICF model, he explained.

Bean concluded by saying we need to harmonize concepts and to identify ways to bridge concepts on functioning and rehabilitation that advance research, so as not to repeat the miscommunications and misunderstandings in geriatrics and gerontology that occurred when the ICF was initially introduced.

Standardized Collection of Functioning Information

Birgit Prodinger, University of Augsburg (Germany), discussed the challenges and opportunities in the standardized collection of functioning information for research in rehabilitation and healthy longevity. She explained that functioning information is collected using various tools and at various levels, including micro (patient and provider interaction), meso (service provision and payment), and macro (planning, implementing, and evaluating policies and programs) levels and available through clinical, cohort, and population studies, as well as administrative and clinical data. A challenge in data collection is the comparability of the data. While some measurements of body function and structure can be converted easily (e.g., feet to centimeters), information collected about activity and participation are more complex to translate, which challenges comparability. Prodinger described three instruments for assessing mobility that address similar concepts from different perspectives: Can you walk 500 meters on a flat surface without an aid or assistance? Are you able to walk outdoors on flat ground? How well are you able to get around, and how satisfied are you with your ability to perform your daily activities? The first question centers on intrinsic capacity, the second addresses a person’s actual daily life performance, which may include the use of assistive devices, and the third is a subjective appraisal of the person’s own ability to do the activity and their satisfaction regarding the activity.

Not only is conceptual equivalence (i.e., that instruments or items are measuring the same concept) needed for comparability but there also needs to be metric equivalence (i.e., that numerical measures or scoring align), she explained. For example, a 3 on the WHO Disability Assessment Schedule indicates moderate problems,³⁸ but a 3 on the 36-Item Short-Form Health Survey indicates severe problems. Solutions for comparability challenges, she said, include standardizing data collection as well as reporting. Standardizing data collection requires changing practices, which may result in losing comparability with previously collected data. Unifying reporting requires agreeing on standards for reporting functioning information, including developing a conversion factor. A benefit to this approach is that it allows researchers to continue using existing data collection tools, which enables comparability over time, she added. However, she advocated for using both approaches, and mentioned ClinFIT as an example for standardizing data collection and the ICF Standardized Assessment and Reporting System for standardizing reporting.

Prodinger outlined three characteristics of functioning that are of value in rehabilitation but also present challenges for researchers. (1) Functioning is multidimensional, and all dimensions need to be assessed. She noted that ICF core sets can guide researchers in thinking about all dimensions when collecting information. To illustrate the importance of assessing all the dimensions, Prodinger expanded on a study that sought to expand documentation on spinal cord injury which found that in the acute phase the focus is on body functions and structures, with limited focus on activities and participation or environmental factors, whereas in the early long-term setting, body functions are the least important (Pongpipatpaiboon et al., 2020). (2) Functioning is interactive, and lived health is an outcome of the interaction between a person’s capacity and the environment in which they live. Thus, it is necessary to collect the information on the environmental factors to understand disablement and enablement processes. (3) Functioning is continuous, and changes in functioning need to be interpreted throughout the rehabilitation process, as people enter rehabilitation at different levels of functioning and their functioning changes over time. More research is needed to understand the minimal clinically important difference of such changes, or the smallest change or improvement in a treatment outcome that a patient would identify as important, because that information can inform interpretability to inform regulatory and financing decision making, she explained. Prodinger concluded by saying that functioning, as the main outcome of rehabilitation, uniquely positions rehabilitation as a health strategy at the intersection of various disciplines. But we need to have the information about people’s functioning in order to support rehabilitation as a viable health strategy.

Using Functioning Data for 360-Degree Research

Jan Reinhardt illustrated how to operationalize functional data and research in an ongoing trial in China. He explained that many OECD countries face growing health care spending with only marginal improvements in outcomes (OECD, 2023; World Bank and WHO, 2019). China is establishing new payment models similar to those of the United States wherein cost estimates are independent of improved health. In a health system, reduced costs up front may lead to greater costs elsewhere (e.g., follow-up treatment episodes) because lower-cost care does not necessarily yield better health outcomes. He explained that a better approach is to integrate functioning as a core indicator in the payment system for baseline health, treatment targeting, and outcomes, which enables a payment system that improves health.

Reinhardt and his colleagues are seeking to develop a performance-oriented payment system for rehabilitation. Using data from a multicenter cohort study at 11 hospitals in China and an ICF-based metric from the rehabilitation set, they found that only 615 of the 2,020 patients improved meaningfully,³⁹ which affects estimated costs for the population as total inpatient rehabilitations costs increase for patients who experience no improvement or worsening outcomes Then, they used a cluster-based approach based on 17 ICF categories to stratify the population into three groups, whereby costs for improvement aligned with baseline functional status at entry: mild, moderate, and severe.⁴⁰ Using a machine learning approach, the team identified a support vector machine model that can predict average costs and is now considering how to use this model to develop performance-oriented payment algorithms and incentives for patient improvement. Although the study’s analysis remains preliminary, he drew several conclusions: meaningful improvement of functioning will require more investment than the current average; baseline functioning is an important predictor of costs within a diagnostic group; key performance indicators drawn from functioning information can be used for benchmarking and performance-oriented payment components; and using functioning as a core indicator enables payment systems to offer rewards for improving health.

Panel Discussion

During the discussion, a participant asked how to advocate for functioning as a priority when some members of a health team may not think of themselves as part of a rehabilitation team. Bean replied that the agefriendly health systems have it right because functioning is shown in research to usually be the primary concern for individuals seeking care; providers may need to be educated about how to measure functioning and how it is conceptualized. He reiterated that work is needed to communicate about ICF outside its field. Prodinger noted that using the ICF as a frame of reference to link existing clinical research data conceptually and metrically could be a good approach, though access to the data may be a mitigating factor.

A workshop participant asked how to bridge the gap between research and practice. Bean brought up the opportunity to work with implementation researchers under the health services umbrella and said implementation research can shed light on how interventions should be packaged and which ones are truly effective. Marija Glisic asked about the dichotomy between the need for standardized rehabilitation interventions to improve “the black box of rehabilitation” and the emerging development of personalized rehabilitation strategies, such as assistive devices. Bean replied that in order to show the efficacy of a treatment, it is critical “that we understand what the contents of that treatment are.” Reinhardt countered that the black box may serve to return decision-making power to clinicians.

Eleanor Simonsick restated her concerns about the “tyranny of low expectations,” pointing out that rehabilitation is expected to raise patients’ abilities to a level that most people would still consider disability and called for developing a way to “capture function that isn’t about loss or incapacity, but also considers levels of actual capacity.” Bean agreed and said that we need measurements that reflect a broad range of capacity, especially for the aging population. He added that basic continuous measures, such as gait speed, are a powerful predictor even among younger people, though context is important.

Reflections on Developing a Research Agenda for Functioning

On the second day of the workshop, Engkasan shared the discussion of the breakout group on research.⁴¹ She presented the idea of establishing human functioning sciences as a new field, using the examples of bioinformatics, digital health, and evidence-based medicine as precedent. Creating a distinct discipline would facilitate broader participation from stakeholders outside the rehabilitation field, such as universities, hospitals, professional rehabilitation organizations, and those developing assistive technology, she asserted.

Participants in the breakout group also discussed using ICF as a reference system for developing standardized reporting and assessment tools but stated that curriculum and education on operationalizing ICF is needed because many methods currently in use lead to low-quality evidence. Reinhardt added that education and training are also needed on best practices for human functioning research. Engkasan reported that the group lacked sufficient time to discuss how to ensure that all the building blocks of the health system (see Figure 2) are researched appropriately.

NiCole Keith asked how to get health systems to cooperate with researchers by sharing data when they are disincentivized to do so because of competition among themselves. Reinhardt said that observing how health systems research is implemented in other countries may help, and some international groups have ongoing work to discuss how payment systems work in different countries. Additionally, he cited work on indicators for implementing the United Nations Convention on the Rights of Persons with Disabilities.

Abderrazak Hajjioui asked how research can be translated into health policy, guiding advocacy groups, educators, and policymakers. Engkasan responded that the research breakout group discussed collaborating with existing organizations to disseminate research findings and emphasized training researchers on moving beyond publication to disseminate their findings by becoming visible in the media and writing policy briefs.

Advocating for Functioning as the Third Indicator of Health

Dorothy Boggs, London School of Hygiene and Tropical Medicine (United Kingdom), presented on challenges and opportunities of advocating for functioning as the third indicator of health and focused on population-level functioning, rehabilitation, and assistive products (e.g., hearing aids, glasses, walking aids). Boggs noted that approaches for measuring functioning need to include both self-reporting and clinical assessments, which will require simplified messaging and explanations using ICF. She identified a research gap for a multidomain survey assessment tool that combines both self-report and clinical assessments, including functional assessments, to measure functioning and the need for rehabilitation and assistive products (Boggs et al., 2021a).

Hybrid tools can use technologies, such as artificial intelligence, to shorten assessment times and incorporate all six ICF components (see Figure 2). An example of a hybrid multidomain tool is the Functional Needs Assessment Tool (FNAT), developed in collaboration with the Assistive Technology 2030 research consortium.⁴² FNAT is a population survey method for identifying needs for services, such as rehabilitation, and assistive products, such as glasses and hearing aids, as it is estimated that 2.5 billion people worldwide would benefit from assistive products (WHO, 2022c). FNAT uses a mobile app and is built using existing survey tools, such as the Washington Group Extended Set on Functioning⁴³ and rapid survey methodology developed by the London School of Hygiene and Tropical Medicine for vision, hearing (Bright et al., 2019), and mobility (original tool, Atijosan et al., 2007; updated in Boggs et al., 2021b).⁴⁴ The tool was field tested in Kalugu, Uganda, in 2023.

Boggs asserted that tools such as FNAT are needed to improve the metrics available for planning rehabilitation, assistive products, and more, and these data can help build the economic case for functioning. The economic case can also reassess how to value health and well-being, including the cost of inaction. For rehabilitation, more economic research is available from high-income countries than from low-income countries, and that research typically focuses on cost benefits and cost-effectiveness related to specific conditions (e.g., cost benefits of rehabilitation from a stroke) (Mills et al., 2017). For disability, existing research tends to focus on the harms and costs of disability, but shifting to a positive focus could include looking at the cost benefits of social assistance programs that help people with disabilities return to work, she explained. For assistive technology, Boggs used the example of the Global Partnership for Assistive Technology ATscale case study, which demonstrated a nine-to-one return on investment, identifying four assistive products as priorities: hearing aids, prosthetics, eyeglasses, and wheelchairs. ATscale presents benefits in different sectors, including the economic, social, and education sectors, and at user, family, and society levels (ATscale, 2020; see Figure 9).

FIGURE 11

Assistive technology demonstrates a nine-to-one return on investment. NOTES: CRPD = United Nations Convention on the Rights of People with Disabilities; GDP = gross domestic product; LMIC = low- or middle-income countries; QALY = quality-adjusted life-year. (more...)

Boggs discussed challenges and opportunities for building the economic case for functioning, including lack of economic data and limited return-on-investment research, for targeting multisectoral and interdisciplinary approaches, and for focusing on populations with the most need, such as the aging population. Boggs concluded by proposing next steps to achieve “functioning for all,” including decreasing measurement gaps by strengthening survey measurement tools and economic research. These need to include user-led groups, such as organizations for disabled or older adults, as well as case studies.

Raising Awareness: The Policy Advocate Perspective

Ruth Katz, Association of Jewish Aging Services (United States), discussed the importance of ensuring people’s goals are integrated into programs, provided examples of how programs should incorporate functioning, and explained how different programs are financed. Many policies are not informed by evidence despite the existing data, she explained, and policies for health care and rehabilitation in the older population often do not match their needs and preferences. Maintaining quality of life matters to people, said Katz, and among older adults, mobility, independence, and mental health are high priorities. Adults older than 65 years are a heterogenous group and may have different goals, but they typically end up in the same financing programs, where all receive the same services. Katz also said that for different populations, rehabilitation can serve different purposes, such as restoring functioning and independence or improving a person’s functioning so that they can return to work.

Care planning for older adults includes diagnosis and functional assessment, and it is supposed to be based on the individual’s preferences or goals. Although these goals vary among individuals, older adults tend to receive therapies or programs based on broad groupings. Programs are sometimes based on irrelevant or ill-fitting policies, she explained. Adult day service programs in the United States, for example, must follow specific guidelines (such as supporting people at their highest level of functioning) to receive Medicaid funding and might include career services or interactive outings.⁴⁵ These programs might benefit people who are still actively seeking work but are not well suited to the needs or abilities of older adults with dementia. Katz concluded by discussing how policy programs are often disconnected from each other and said that financing for long-term care is especially lacking in the United States for people with middle-level incomes.

New Directions for Health and Disability

Abderrazak Hajjioui presented on different approaches to advocacy efforts to improve functioning and overall health. Defining the concepts of health, rehabilitation, and functioning in a straightforward manner is key with policymakers and stakeholders, and he emphasized how prevention and emergency response can be avenues for advocacy. WHO defines health as a holistic state of well-being, not just the absence of disease, and includes other factors such as access, support for education, and improved environmental conditions.⁴⁶ Hajjioui said the goal of health interventions is improving function. The COVID-19 pandemic, which significantly increased mortality and restricted participation and functioning, required government response and mass health interventions in both prevention and treatment. He added that framing functioning in terms of acute medicine and return to work has been a successful strategy when communicating with policymakers.

Hajjioui said there are different entry points for advocacy and asserted that advocacy starts with education “because the students of today will be the leaders and policymakers of tomorrow.” Advocacy approaches need to consider stakeholders’ contexts and perspectives. Governments need to know about human rights approaches, wherein the objectives are dignity and autonomy and increased access. Private institutions want to understand the economic impacts, such as cost-effectiveness and workforce productivity. Consumer organizations respond well to a person-centered approach, with holistic care, empowerment, and engagement, while academic institutions tend to prefer public health approaches, such as prevention and community-based programs. He noted that DALYs can be used to show the value of rehabilitation in improving years lived with disability (see Figure 3). Within the rehabilitation field, advocates should consider prevention (e.g., preventing falls and risk for chronic illnesses), primary prevention through treatment (i.e., beginning rehabilitation at the time of diagnosis), and secondary and tertiary prevention through improving people’s environments and removing barriers to care. He concluded by emphasizing the importance of communicating with policymakers that “it’s time to end the global neglect of rehabilitation.”

Panel Discussion

NiCole Keith, asked who, in addition to health economists and policymakers, should be part of an advocacy team. Katz replied that such teams can include family members, individuals who use care services, students, advocacy organizations, and boards of organizations. Boggs reiterated that user-led organizations such as those for people with disabilities or for older adults are important.

A workshop participant asked about the gap between aging and rehabilitation in developing countries, stating that one cannot assume the association between the two is automatic, and asked what steps could be taken from an advocacy perspective. Hajjioui agreed that this is a problem in LMICs, and that work is needed to educate professionals in the acute medicine workforce (e.g., internal medicine, geriatrics, neurology). Boggs responded that her LMICs research has revealed that older adults have a higher prevalence of need, and more data will help demonstrate this. Diana Pacheco emphasized the need for data to show the economic value of rehabilitation. Francesca Gimigliano added that it is important to advocate for rehabilitation as an investment to improve functioning rather than another health expense.

Sara Rubinelli, University of Lucerne (Switzerland), stated that although some suggest that functioning and rehabilitation are fuzzy concepts, clearer definitions are now available. Boggs responded that while the concepts are clear to those in the room, they can be overwhelming for audiences unfamiliar with frameworks such as the ICF. Boggs added that case studies are key to communicating effectively, recalling Hajjioui’s example of a well-known athlete’s injury, subsequent rehabilitation, and improved performance. In fact, she said, in discussions over lunch during the workshop, participants quickly resorted to tangible examples from their own families, reinforcing the utility of case studies as communication strategies. Hajjioui added that advocacy for functioning is challenging because of the low levels of knowledge and education about the concept, so education is a critical component.

Reflections on Promoting Advocacy for Functioning and Rehabilitation

Leonardi said that her breakout group discussed how, for many countries, rehabilitation is not embedded in the health care system as well as other strategies such as prevention, promotion, diagnosis, and palliative care.⁴⁷ Raising awareness is needed first, she said; the issue of rehabilitation and functioning needs to be clear at all levels of policy, and case studies and identifying clear problems and solutions will help. She underlined the term biopsychosocial model as part of communications around functioning, which she said has “a bit disappeared.”

Leonardi said that functioning implies coordination between services along a continuum of care across the lifespan. However, most of the strategies for noncommunicable diseases don’t include strategies about rehabilitation or functioning. Participants from the breakout session also discussed opportunities for collaboration. Some suggested that WHO should embed functioning and rehabilitation in all its programs and argued that the World Rehabilitation Alliance should consider supporting the concept of functioning, not only address deficits and impairments. Leonardi stated that the United Nations Convention on the Rights of People with Disability, which she described as a “Trojan horse,” has been endorsed by 192 countries, and its Article 26 could be used to support the introduction of rehabilitation.

Somnath Chatterji suggested that advocacy might best be accomplished by communicating the instrumental value of functioning insofar as it enables people to do what they want to do and thereby enhances wellbeing, rather than discussing intrinsic value alone. Leonardi agreed but also mentioned that different countries value the aging population and people with disabilities in different ways.