Describing the Value of Physical Therapy in a Complex System Using the Socio-Ecological Model : Journal of Acute Care Physical Therapy

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Describing the Value of Physical Therapy in a Complex System Using the Socio-Ecological Model

Crick, James P. Jr; Alain, Gabriel; Quatman, Carmen; Juckett, Lisa; Quatman-Yates, Catherine C.

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Journal of Acute Care Physical Therapy 14(1):p 1-9, January 2023. | DOI: 10.1097/JAT.0000000000000209
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The US health care system is expensive relative to other developed nations and is often characterized by waste.1–3 Assessing outcomes of care is necessary for quality assurance and improvement, yet deciphering and quantifying how any 1 individual or intervention impacts even the simplest of outcomes is often difficult. This is because our health care system is extraordinarily complex and traditional methods are insufficient to describe its inner workings. In the acute hospital setting, this is particularly true where myriad professionals, procedures, medications, and other interventions are applied to patients who have their own unique medical and social history, preferences, and response to treatment.

Complexity science, a subcomponent of systems science, offers a chance to reconceptualize our understanding of health care from a disorganized set of independent actors with a patient at the center to an environment of connected parts operating together and adapting on the basis of inputs and outputs. Interacting parts and processes are influenced by upstream and downstream variables (see the Table); thus recognizing and assessing these interactions are essential to improving the value of health care. Jewell et al4 proposed a value proposition for physical therapy that required identification and adoption of best practices, measurement of clinician performance, and cost-effectiveness evaluations to enhance claims of value. However, the profession's value is heavily influenced by contextual factors that are often overlooked and underappreciated in physical therapy practice—particularly in the acute care setting. When compared with other care settings, the influence of acute physical therapy intervention may not be as directly deduced. The purpose of this conceptual article is to apply complexity science principles to acute care physical therapy in order to provide perspective on the value of the physical therapist in the hospital environment and on the contextual factors that influence the profession's value. Informed by complexity science principles, we present the Socio-Ecological Model for Acute Care. The original Socio-Ecologic Model is depicted in Figure 1. Our adapted model (see Figure 2) presents a set of constructs to help clinicians and researchers identify and describe the interacting factors that, in this case, influence physical therapy care and the overall patient experience. We also provide recommendations for how researchers and clinicians can empirically examine these socioecological factors and their association with the profession's value in the acute care setting.

TABLE. - Glossary of Complexity Science Terms
Complexity Science Term Definition
System Literally “organized whole,” a system is a set of parts that interact in particular ways to accomplish a common purpose.
Complex system A system of systems in which the component parts cannot fully explain the system. A full understanding can be identified only retrospectively.
Upstream The origin or source of an issue that is experienced in a different space or location.
Downstream The proximate problem that requires some form of action. Often, the seen or felt consequences of upstream problems.
Reductionism The concept that whole domains can be broken down and understood as the sum of the individual component parts.
Complex adaptive systems A dynamically interacting set of agents that are considered more than the sum of their parts and self-organize in response to changing conditions.
Self-organization The stable patterns that are demonstrated by autonomous agents, each acting according to the unique rules imposed upon them by the system, without the direct influence of hierarchical control.
Agent The individual components of a system that interact and self-organize. Oftentimes, they are individuals but can also be environments or artifacts.
Attractor The structural characteristic that draws the system together. In the case of a hospital, often a patient and his or her needs.
Coevolution Describes the process at the level of the individual agent to continually adapt to the changes within a system.
Emergence Characteristics of a system that are not evident when considering individual components of the system. In complex systems, results from the nonlinear and unpredictable interactions of self-organizing individual agents.
Broker Entity that links 2 or more agents to improve communication and connectivity within a system. Typically considered an individual.
Resilience A characteristic of a complex system in which the system dynamically adjusts processes and operations in response to changing conditions.

The Socio-Ecologic Model Describing Multiple System Levels.
The Socio-Ecological Model for Acute Care: a representation of a hospital as a complex adaptive system. Upward and downward influences describe the interrelatedness of the system levels. The system is dynamic and is constantly evolving and adapting. The effects of the system are most tangible for clinicians at the lower levels, yet these lower levels are influenced by and inextricably linked to the higher levels.


A system is a collection of entities (ie, widgets, molecules, people, businesses) that interact in such a way that their resulting collective behavior is not immediately apparent by viewing the collected items separately.5 Consider a bicycle as a system consisting of components such as wheels, a frame, handlebars, and a chain. Each component is connected to each other allowing propulsion down the road. If one component is removed, the purpose of the bicycle is lost.


A subsystem is a “smaller” system that is part of and contained by a larger system.6 When subsystems are organized to meaningfully interact with other subsystems, order is created where previously there was none. In such cases, the whole becomes more than the sum of its parts. This is called emergence. Emergence indicates that a system has qualities its subsystems or components on their own do not.7–9 Sometimes a system behaves in a way that contradicts the behavior of its subsystems or components. An example of this can readily be observed in water. Water is composed of hydrogen and oxygen. Separately, each is considered an extremely flammable gas, but when combined together, hydrogen and oxygen are used to extinguish fire. An acute physical therapy corollary is demonstrated in early mobilization in intensive care units. Mobility is clearly a physiologic stressor to a patient who is already physiologically impaired because of critical illness, yet patient outcomes consistently favor early mobilization. This is a primary argument for the necessity of systems science as a discipline and why understanding the organization of a system is valuable.


A complex system is a system of systems. Gallagher and Appeneller10 define a complex system as “ whose properties are not fully explained by an understanding of its component parts.” By their stochastic nature,11 complex systems are commonly unpredictable.7,12–15 Complex systems should not be confused with complicated systems.7 Complicated systems may involve many interacting parts, but they can be readily deconstructed and reconstructed from the component parts and are predictable. For example, a spacecraft sending astronauts to the international space station is a complicated system. Using advanced engineering and experience, missions are predictably successful in nearly all circumstances. If it were a complex system, it would likely crash or miss its target quite often because in a complex system, the interactions between components are so multifarious that predicting behavior becomes much more difficult or impossible.7,12–15


In simple linear systems, observed behavior can easily predict what will happen next (such as in the example of the bicycle mentioned previously). As a system becomes complicated, the number of involved components increases, but the results remain predictable (such as in the example of the spacecraft mentioned previously). Complex systems, by contrast, often exhibit the quality of nonlinearity in which even small causes can manifest large effects (and vice versa).7,8,16 A nonlinear system can quickly change from stable to unstable or vice versa. An example of this is thrombosis, where a clot that is a tiny cause relative to a large complex system can produce deadly effects. This is occurring in a complex system, however; thus, the same clot may produce completely insignificant effects depending upon other system factors (such as in what vessel it is lodged, or the path it takes as an embolus). In acute physical therapy, an example of this is seen in the symptoms of acute benign positional paroxysmal vertigo. Seemingly miniscule location changes of otoconia produce substantial experiences of vertigo, and simple maneuvers may reliably produce profound relief.


A complex adaptive system (CAS) comprises variable agents that mutually respond and influence the behavior of other agents within the system in ways that are not immediately predictable.7,17,18 Adaptive responses and influences among agents can include things such as regulating the strength of relationships within the system, changing the composition of relationships through self-organization, or optimizing the alignment of the system with its resources and environment.7,8 Hospitals have been described as a form of CAS.7 The hospital setting is a highly dynamic CAS where multidisciplinary care and care patterns are known to be influenced by systemic factors.19,20 We understand the factors that matter to hospitals such as outcomes, finances, and customer satisfaction. However, we do not fully understand how the factors interact with one another, making the system complex.


Our current health care system is known for “focusing and acting on the parts without adequately appreciating their relation to the evolving whole,” as Stange21 defined fragmentation. Examples abound of this fragmented view in hospital care, including for patients following hip fracture repair who are receiving postoperative care from multiple service lines. For example, mild to moderate postoperative anemia may limit participation in mobilization due to fatigue (influencing the physical therapist). A hospitalist may be motivated to transfuse, given the history of coronary artery disease, yet surgeons may be reluctant as complications, including infection, are known to increase in this population posttransfusion.22–24

Poignantly, the aforementioned definition of fragmentation is the antithesis of complexity, suggesting that our “fragmented” health care system is indeed deeply reductionist in practice. In physical therapy, this may be best characterized by the lack of continuity in care between settings. For a patient transitioning between levels of the health system (hospital, skilled nursing, inpatient rehabilitation, home health, outpatient), he or she may see different physical therapists in all settings, each of whom has established different plans of care and varying goals, without any communication with the preceding therapist.

Reductionist approaches characterized much of scientific progress over the last century but have proven insufficient for inquiries with nonlinear relationships.8,13 Reductionism breaks problems down into component parts, tests a solution, and attempts to apply the solution to the whole of the parts.7 This is clear in the methodology of randomized controlled trials, considered the preeminent study design to deduce causation, in which potential confounding variables are strictly controlled. Limitations reported in these studies rightly suggest that results may not be transferable to other groups or environments due to this control, acknowledging that the solutions generated are limited by the self-imposed restrictions of the study. For example, in early mobilization following stroke, robust evidence generated by the AVERT trial25 excluded patients with preexisting disability, unstable medical condition, and competing care needs. It could be argued that some of these patients may disproportionately benefit from early mobilization following a stroke, yet we cannot directly apply the AVERT evidence to these cases.


Physical therapists are routinely consulted by physicians in the hospital to evaluate and treat physical impairments and functional limitations. They provide recommendations for safe discharge locations, required equipment and precautions, and further rehabilitative needs.26–29 Empirical research for the value of physical therapy on discrete patient outcomes in the acute care setting is sparse.

“Complex” is not a novel descriptor in the acute care physical therapy literature. In a survey to describe nationwide knowledge, skills, and behavior, Gorman et al30 described “complex environmental influences” and intervening in “medically complex patients” as areas in which the acute care physical therapist distinguishes himself or herself from other specialties. Regarding patient care, the myriad patient-focused factors such as prior level of function, home environment, social and economic support, current illness status, and physical and cognitive ability to participate must be individually considered for each patient encounter. The confluence of these factors and the significance of contextual considerations have been previously described for cardiorespiratory physical therapy31 but not through the lens of complexity.


The confluence of unpredictable responses to simple interventions is exemplified by a case example (Box). This vignette demonstrates a vital principle of intervening in complex systems: downstream consequences must be mitigated by addressing the factors upstream, resulting in updates to the system, which may prevent avoidable harm.

BOX: Applied Case Example

After spending most of the previous day on a gurney in the emergency department, Mr S, an older adult man, finally settles into a room on the ward where his vitals are taken every 2 hours overnight and 2 laboratory draws are conducted; thus, his sleep is limited. Owing to his age68 and the fact that he was admitted overnight, a bed alarm is placed on his bed as a precaution and a request made that he use a hand-held urinal for current toileting needs. Upon arising in the morning, he sets off the bed alarm while trying to sit up to reach his phone to call his family resulting in a flurry of activity into his room and a stern reminder to not get up without assistance. Shortly thereafter, Mr S calls for the assistance of a patient care associate to ambulate to the bathroom, and upon standing (for the first time in nearly a day) he is slow to move and grabs onto the wall to steady himself. After toileting and returning to bed where the bed alarm is reactivated, the patient care associate informs the nurse that the patient seemed “off-balance.” There is a question as to whether the cardiologists will pursue invasive testing; thus, his diet was assigned “nothing-by-mouth” by the emergency department resident, and he does not receive breakfast. While awaiting laboratory results, he takes the medications offered by his nurse and awaits clinical visits from the medical team to determine his plan for the day. He finally receives a lunch tray and requests to sit in the chair to eat; however, upon standing at the edge of the bed, he becomes light-headed and requires significant physical assistance to safely return to sitting at the edge of the bed, narrowly avoiding a fall. His nurse arrives, checks his blood pressure in sitting, which is 98/60, and he is told to remain in bed for now while she informs the medical team. He receives no further updates that day and patiently remains in bed while awaiting a plan for the chest pain that brought him to the hospital but dissipated in the emergency department.

A physical therapy consultation is requested for Mr S, given his near-fall, and he is seen at 730 am after another night of disrupted sleep. His examination suggests no deficits in strength, sensation, integument, and cognition and communication ability. His orthostatic vital signs are normal. After spending nearly the entirety of the last 36 hours in bed, he requires 2 attempts and generation of forward momentum to come to standing, and his gait pattern is unsteady over the course of 100 ft. The therapist conducts a 30-s chair stand test (30 CST) for which he completes 12 repetitions. The therapist interprets this as at the low end of average, and given his apparent ease of fatigue, the fact that he lives alone, and the requirement for navigating stairs to enter his apartment, suggests consideration of a skilled nursing facility disposition.

In the case of Mr S, there are several instances in which a typical intervention shaped the environment for a subsequent action or intervention. For example, consider the downstream influences of the innocent application of an overnight bed alarm for a new admission. Mr S unknowingly set off the bed alarm in the morning, which resulted in a rush of staff entering his room to avoid a potential fall. His room was then marked as “fall risk” outside the door. His nothing-by-mouth status combined with his typical morning dose of metoprolol (an antihypertensive) resulted in an orthostatic event causing a near-fall. This resulted in further bed rest. The unfortunate convergence of interrupted sleep, reduced mobility, lack of nourishment, and a distressing environment resulted in allostatic overload,32 which was reflected in his physical therapy evaluation as “apparent ease of fatigue, difficulty with sit to stand transfer, and unsteady gait.” Considering the case of Mr S from a purely reductionist view may cause some to conclude that he is simply weak and unsteady, as deduced from his functional mobility evaluation. Suggesting daily physical therapy while in the hospital could ultimately assist him to return to his prior level of function and avoid a post–acute care facility stay, but that is a downstream solution to this complex problem.

Viewing the vignette from the lens of complex systems, physical therapists add value by quickly addressing as many harmful factors as possible. Physical therapists' value to the patient may be increased through education regarding fall risk mitigation strategies, individually tailored methods to optimize hospital mobility, the importance of normal circadian rhythms33,34 and sleep hygiene,35 and the influence of maintaining close to normal nourishment. Collaboration with or recommendation for referral to other colleagues, such as dieticians, occupational therapists, or speech-language pathologists, may also help close potential care gaps. In the case of Mr S, the therapist may conduct additional testing to justify recommendations to maximize functional independence. Were a Timed Up and Go test completed without a device in 9 seconds, it may be reasonable to suggest to the staff that Mr S be permitted to ambulate throughout his room and in the area near his room without staff assistance. Given his normal cognition, the therapist educates him on symptoms of concern and risks for falling, and any changes in status should be immediately reported to the nurse.

For researchers, the inherent value of physical therapy in the acute setting has been a difficult construct to measure on the individual patient level because acute care physical therapy is typically provided in concert with a variety of other interventions and environmental variables. For example, patients are often cared for by a multidisciplinary team who provide interventions in a setting unfamiliar to the patient. Oftentimes, these interventions are initiated at the height of acute illness. Simply said, physical therapy provided in the hospital is a component of a complex care plan, thus confounding factors abound. Furthermore, a key gap in the literature is regarding reliable prediction tools for determining which patients may maximally benefit from acute care physical therapy interventions. Difficulty identifying which patients will benefit the most from physical therapy obfuscates the value rendered to the system. A recent publication makes this point by suggesting that overutilization of physical therapists for general mobilization may be commonplace.36


In complexity science, self-organization refers to the stable patterns that are demonstrated by autonomous agents, each acting according to the unique rules imposed upon them, without the direct influence of hierarchical control.8,16,37 In a CAS such as a hospital, each clinician and staff member operate independently to accomplish their own purposes for the good of the patient. Self-organization is evident as each agent reacts to the other agents in ways that are unpredictable and nonlinear, resulting in near infinite permutations of care patterns. Consider, for example, how a given unit can sustain a certain patient caseload despite daily variation in skill mixes and staffing ratios for nurses, patient care associates, therapists, and support staff. All of these various agents coevolve37 perpetually, adapting to the changing environment as the other agents operate and the system emerges.

Interdisciplinary communication is paramount for maintaining the continuity of care for patients whose needs are unique and changing. Previous research has suggested that communication is hindered by power dynamics, existing culture, and the belief that performance rests at the level of the individual practitioner and not the team.38 Further barriers to effective teamwork in a hospital setting include the continuous turnover of staff (ie, shift changes) and the fact that patient needs are unique; thus, individual practitioners are all part of a multiplicity of teams.39,40 Managing the constant flux of individual patient needs with the resource availability on a given unit and in each hospital system requires system-level solutions.

The behavior of a system to dynamically adjust processes and operations in response to changing conditions is called resilience.7,41 The resilient physical therapist can not only expertly intervene for individuals in need of skilled rehabilitation but can also manage additional needs that benefit the unit. Value-added benefits by physical therapists may take various forms such as prioritizing patients to facilitate improved medical progression (such as in an intensive care unit assisting with ventilator weaning),42 mitigating hospital-acquired delirium and cognitive loss through contributions to multimodal care pathways,43–47 providing mobility recommendations for individuals at their baseline functional status for whom skilled rehabilitation may not be currently warranted (such as mobility promotion for a patient with a prior amputation who independently ambulates with a prosthesis), and providing educational in-services to other staff regarding body mechanics and safe patient handling.

Considering value not just at the level of the patient but to the unit as a whole may provide a challenging mental construct for the physical therapist. For a clinician practicing on a given unit, practice patterns will develop on the basis of prior experiences and training, the culture and expectations of the unit, and the influence of other clinicians and environmental factors on the ability to best intervene for a patient. Crucially, evidence-based practice uptake may be hindered by lack of teamwork or confusion of roles.48 Thus, an understanding of the therapist's unique role in each system and on a given unit is paramount.

In our case example, the physical therapist may optimally serve as a bridge7 for the independent individual who entered the emergency department to interact with the system in such a way as to promote independence and anticipate a discharge home. In a circumstance in which hospital mobility is not prioritized, and allostatic overload increases, the risk for a posthospital syndrome49 escalates and the odds of a home discharge are likely reduced. By serving as a broker7 between clinical disciplines, the physical therapist is positioned to navigate the hierarchical levels characteristic of hospitals in order to advocate for maintaining a person's normalcy while simultaneously reducing his or her risk for adverse events. Here, too, value is added by establishing clear communication pathways from patient to therapist and from therapist to the other members of the care team.

Manifold methods to determine staffing ratios, patient prioritization and triaging guidelines, and departmental productivity exist. For physical therapy researchers and managers, increased transparency in the form of reports and publications may benefit the acute care physical therapy community as a whole. Hull and Thut50,51 have provided a unique example applied to their system, the Therapy Value Quotient (TVQ). However, to our knowledge, the utility of the TVQ has not been reported in other markets, nor is there any published discussion regarding potential uncaptured value to the patient, unit, or system in the aforementioned quotient. Our purpose is not to dissuade systems from using the TVQ but rather to promote future published discussion to enhance consistent application of value standards to acute care physical therapy.


Physical therapists provide primary value to the health system by intervening to avoid the predilection toward hospital-acquired disability and by providing accurate discharge recommendations.26 In a qualitative study, Jette et al29 suggested that 4 constructs are used by therapists in making discharge recommendations—patients' current functioning, patients' desires and goals, patients' ability to participate in their own care, and patients' own life context. These constructs are considered in conjunction with regulations and other health care team members, with the resultant recommendation emerging on the basis of these factors. Although consideration of each individual patient is crucial to providing optimal care, so too are the influences of clinicians, support staff, family members, physical environments, and factors such as insurance coverage and social determinants of health on the whole system. Thus, it is important to note that the value the acute physical therapist provides not only exerts an influence on other care team members such as physicians and nurses but also has effects on patients after discharge.52

At the hospital system level, physical therapy publications hint at principles of complexity science such as nonlinearity and unpredictability. For example, the hospital environment influences clinical decision making and patient prioritization53 while patient transitions between units can significantly affect the amount of physical therapy resources offered.54,55 The divergent amount of therapy resources made available may also be partly explained at the level of the clinician as therapists conceptualize their patient prioritization along a spectrum of patient- or system-driven thinking.56

The complex systems concept of downward causation suggests that microlevel behavioral constraints are influenced by feedback from the emerging system9 (see Figure 2). Working within the expectations of a rehabilitation department while adjusting to the constantly emerging characteristics of the hospital system, it is important for therapists to recognize systemic influence and be innovators for change. As described in our case example, therapists may optimize value through patient advocacy (value to the patient) that changes the interaction between the patient and the unit (value to the unit), resulting in an earlier discharge to home as opposed to a delayed discharge to a skilled nursing facility (value to the system). We implore physical therapists to consider their practice through this lens of complexity. In doing so, therapists can begin to better understand how the system influences behavior for patients, other clinicians, and themselves.

An important opportunity for the research community is that physical therapy discharge recommendation research remains largely unexplored. Although data on the appropriateness of physical therapy discharge recommendations are available, the true precision of physical therapy discharge recommendations remains elusive. The primary outcome of interest in studying the effect of physical therapist discharge recommendations is typically readmission, yet it is unknown whether overly conservative discharge recommendations are able to explain the discrepancy in observed readmission rates (or what effect this has on ultimate patient outcomes).


Physical therapists' influence on the health care system at the level of policy is perhaps less obvious. For example, in state practice acts expanded to include direct unrestricted access, patients seen by physical therapists for low back pain in the outpatient setting had lower health care utilization and costs.57 Furthermore, as direct access became more ubiquitous across the country, research showed that primary care visits involving musculoskeletal injuries decreased.58 Thus, physical therapists may be acting as a valuable buffer between the patient and the primary care provider.

Deducing policy effects on acute care physical therapy is less clear than in the preceding example. Although physical therapists in the acute setting have had to adjust to system-level changes in practice acts, health policy, and regulatory frameworks, their resiliency may be in part due to being considered an ancillary hospital service and thus not directly mentioned in specific policy. The effects of policy on acute care physical therapy are highly complex and involve multiple actors including administration, accrediting bodies, and insurance. Accrediting bodies for comprehensive certification in total joint replacement59 and stroke60 have rehabilitation-specific requirements that must be met. It should be noted that these measures are not specific to physical therapy and simply require that ambulation and postoperative functional status are assessed on the day of surgery (in the case of total joint certification) and rehabilitation needs are assessed (in the case of stroke). This should serve as a clarion call to the acute care physical therapy community advocating for our role and empirically demonstrating value must be prioritized.

Most acute care physical therapists are compelled to focus on the specific responsibilities of their job duties (ie, patient care responsibilities) making it difficult for them to engage with ideas beyond their immediate area of responsibility. This is likely driven by productivity metrics, which commonly measure therapist-patient interactions with minimal incentive to participate in system-level conversations to develop upstream solutions. However, this does not mean that physical therapists cannot influence policy at a systems level. Local and progressive advances in areas such as quality improvement, value-based care, and evidence-based practice cause emergent changes to the CAS, sending waves to the macro and micro levels. This is crucial for the future of acute physical therapy as the systems thinking framework encourages a progressive accumulation of insights rather than being a system that reacts to another.61,62 Understanding the effect and consequences of these waves is an enormous undertaking but worthwhile if we are to fully understand our influence and value.


Several lines of future research would help provide further objective evidence for the empirical value of acute care physical therapy. Future study in this area should explore the influence of hospital contextual factors on the practice patterns of physical therapists (eg, the influence of variable productivity standards, standardized protocols, experience level, access to resources). Quality improvement initiatives to promote practice optimization, developed according to complexity principles and considering contextual characteristics, can then be tailored to physical therapy professionals to enhance self-efficacy, decrease variability in practice, and reduce practice frustrations.31 With surveys suggesting that as many as half of physical therapists are considering a professional change in the next 5 years63 and with burnout cited as a primary factor,63,64 it is important that therapists are empowered to be change agents at multiple system levels. This empowerment requires further study. Dissatisfaction with professional misconceptions of the role of the acute care physical therapist65 must be understood and addressed. This includes reported nursing perceptions that general mobility is primarily the responsibility of the rehabilitation therapists.66,67 To best advocate for our true value in hospital practice, we need to better distinguish between patients who need general mobilization (all of them) and those who need the specialized skill of a trained and licensed physical therapist. This is nontrivial as we have described that physical therapy is often considered as part of the system, and patients tend to improve in the system, obscuring exactly to what extent the physical therapy provided contributed to positive patient outcomes. At the system level, it is incumbent upon researchers to identify novel strategies for understanding the accuracy of our discharge recommendations.


Acute care physical therapy provides value at multiple system levels, but this value is not always easily attributable. As frontline providers practicing in a CAS, we encourage clinicians and researchers to collaborate and thoroughly evaluate how the factors and relationships depicted in Figure 2 influence physical therapist's value in the acute care setting. Understanding the complexity of these factors and articulating them to diverse stakeholders is a foundational step in creating meaningful change in acute care systems. It is only through appreciating the complexity of the system that we can fully describe our value and advocate for whom physical therapy is necessary for in this environment.


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