Applying the ICF in Rehabilitation Medicine
Gerold Stucki
Nenad Kostanjsek
Bedirhan Üstün
Thomas Ewert
Alarcos Cieza
INTRODUCTION
Functioning is the lived experience of people (1). It is a universal human experience (1, 2) in which body, person, and society are intertwined (3, 4). Over the life span, people may experience a variation in the level of functioning associated with congenital disorders, injuries, acute and chronic health conditions, and ageing. The experience of a limitation of functioning or disability thus is part of the human condition (1). The WHO estimates that as many as 500 million healthy life years are lost each year due to disability associated with health conditions. These are more than half the years that are lost annually due to premature death (5). This figure is increasing not only due to population growth, medical advances, and the ageing process but also due to malnutrition, war, violence, road-traffic, domestic, and occupational injuries, and other causes often related to poverty (6).
With the International Classification of Functioning, Disability and Health (ICF) approved by the 54th World Health Assembly in 2001 (4), the WHO provides a universal and internationally accepted framework and classification (7). The ICF is a promising starting point for the integrative understanding of functioning, disability and health, and the overcoming of Cartesian dualism of body and mind as well as both sociological and biomedical reductionism (8). It is also a promising starting point for the development of rehabilitation practice and research (7, 9).
The objective of this chapter is to introduce the reader to the ICF and how it relates to rehabilitation.
In the first section, we review the history and development of the ICF and describe its structure and validity. In the second section, we illustrate how to use the ICF for the classification and measurement of functioning. Finally, we discuss the current state of the implementation and application of the ICF with a focus on rehabilitation.
THE ICF
The ICF in the Historical Perspective
Clinicians have relied on classifications for the diagnosis of health conditions for over 100 years (10, 11). The International Classification of Diseases (ICD) was first published as a classification of causes of death in 1898 (12). In the meantime, the ICD is undergoing its 11th revision. The ICD was initially used for actuarial reasons to document death. It was later adopted for epidemiology and by public health to monitor health and interventions. Lately, it was used for clinical purposes, mainly driven by the need to classify diagnoses in the context of reimbursement systems including diagnostic-related groups.
By contrast, the first classification of disability, the International Classification of Impairment, Disabilities and Handicaps (ICIDH) (13) was published and released in 1980 for trial purposes only. The ICIDH and other models like the Institute of Medicine model (14, 15), Nagi’s model (16, 17), and the Quebec model (18) have influenced the definitions of rehabilitation (9), the development of rehabilitation practice and research (9), and legislation and policy-making (7, 15). The ICIDH model of disablement represented a real breakthrough in that disability was disentangled from disease by removing the disability section from ICD-8 and creating a separate classification.
Particularly in Europe, there was considerable interest in the application of the ICIDH as a unifying framework for classifying the consequences of disease during the last 20 years of the 20th century. For example, the Council of Europe launched its Recommendation No. R (92) 6 on “a coherent policy for people with disabilities” based on the ICIDH (19). Other publications by the Council of Europe, for example, about the use and usefulness of the ICIDH for health professions (20) document this interest.
However, the ICIDH, which was never approved by the World Health Assembly as an official WHO classification, did not find worldwide acceptance (1, 15). It was criticized by the disability community over time for the use of negative terminology, such as handicap, and for not explicitly recognizing the role of the environment in its model. In the reprint of the ICIDH in 1993, WHO thus expressed its intention to embark in the development of a successor classification.
The ICF in the WHO and the UN Perspective
The endorsement of the ICF by the 54th World Health Assembly in May 2001 mirrors an important shift in the understanding of health and disability by the WHO. The ICF acknowledges that every human being can experience a decrement in health and thereby experience some disability. With the ICF, WHO responds to the need for a unified, international, and standardized language for describing and classifying health
and health-related domains. The ICF is WHO’s framework for health and disability. It is the conceptual basis for the definition, measurement, and policy formulations for health and disability. The ICF thus complements the ICD that is used to classify deaths and diseases (11). To complement mortality or diagnostic data on morbidity and diseases is important since they alone do not adequately capture health outcomes of individuals and populations (e.g., diagnosis alone does not explain what patients can do, what their prognosis is, what they need, and at what treatment costs) (21, 22).
and health-related domains. The ICF is WHO’s framework for health and disability. It is the conceptual basis for the definition, measurement, and policy formulations for health and disability. The ICF thus complements the ICD that is used to classify deaths and diseases (11). To complement mortality or diagnostic data on morbidity and diseases is important since they alone do not adequately capture health outcomes of individuals and populations (e.g., diagnosis alone does not explain what patients can do, what their prognosis is, what they need, and at what treatment costs) (21, 22).
As an international standard ICF contributes to various WHO’s efforts related to the measurement of health and disability. For example, the ICF served as a framework for WHO’s World Health Survey conducted in 70 countries (23, 24). The WHA resolution 58.23 on “Disability, including prevention, management and rehabilitation” approved in May 2005 by the 58th World Health Assembly recalls the ICF framework (8). For the upcoming WHO World Report on Disability and Rehabilitation, the ICF provides the basis for the conceptualization of disability and reference framework for the disability statistics presented in the report. The International Society of Physical and Rehabilitation Medicine (ISPRM) which is the International Physical and Rehabilitation Medicine (PRM) organization in official relation with WHO, is represented on the advisory board of the report and is supporting the DAR team in this development.
While the ICF has been developed by WHO, the specialized agency responsible for health within the United Nations (UN) system, the ICF has been accepted as one of the UN social classifications (4). Therefore, the ICF has influenced the characterization of disability in the UN Convention on the Rights of Persons with Disabilities (25) approved on 13 December 2006 at the UN Headquarters in New York. While the convention does not establish new human rights, it does define the obligations on states to promote, protect, and ensure the rights of persons with disabilities. Most importantly, it sets out the many steps that states must take to create an enabling environment so that persons with disabilities can enjoy inclusion and equal participation in society. However, the ICF provides a more comprehensive approach defining disability than it is used in the UN Convention. Hence, there is the need for a common agreement on the meaning of disability (26).
Development of the ICF
The ICF was developed by the WHO in a worldwide collaborative process involving the active participation of some 65 countries and a network of WHO Collaboration Centers for the Family of International Classifications (WHO-FIC). After three preliminary drafts and extensive international field testing, including linguistic and cultural applicability research, the successor classification which was first tentatively named ICIDH-2, the ICF was finalized in 2000 (4). So far, the ICF has been translated into 37 languages.
The ICF not only was derived from Western concepts but has worldwide cultural applicability. The ICF follows the principle of a universal as opposed to a minority model. Accordingly, it covers the entire lifespan. It is integrative and not merely medical or social. Similarly, it addresses human functioning and not merely disability. It is multidimensional and interactive, and rejects the linear linkage between health condition and functioning. It is also etiologically neutral which means functioning is understood descriptively and not caused by diagnosis. It adopts the parity approach which does not recognize an inherent distinction or asymmetry between mental and physical functioning.
These principles address many of the criticisms of previous conceptual frameworks and integrate concepts established during the development of the Nagi model (16, 17) and the Institute of Medicine model of 1991 (14, 15). Most importantly, the inclusion of environmental and personal factors, together with the health condition, reflect the integration of the two main conceptual paradigms that had been used previously to understand and explain functioning and disability, that is, the medical model and the social model.
The medical model views disability as a problem of the person caused directly by the disease, trauma, or other health conditions and calls for individual medical care provided by health professionals. The treatment and management of disability aim at cure and target aspects intrinsic to the person, that is, the body and its capacities, in order to achieve individual adjustment and behavior change (27, 28).
By contrast, the social model views disability as the result of social, cultural, and environmental barriers that permeate society. Thus, the management of disability requires social action, since it is the collective responsibility of society at large to make the environmental modifications necessary for the full participation of people with disabilities in all areas of social life (29, 30, 31, 32). The ICF and its framework achieve a synthesis, thereby providing a coherent view of different perspectives of health (1).
ICF Update and Future Developments
The ICF published in 2001 will—similar to the ICD—undergo updates and ultimately a revision process. The WHO coordinates the update process, in collaboration with the Network of the Collaboration Centers for the Family of International Classifications (WHO FIC CC Network). Recognizing the importance of personal factors, which are included in the ICF conceptual model, the WHO is also exploring the possibility of developing a taxonomy of personal factors.
To meet the requirements of health and disability information systems in the 21st century, the digitalization of analogue information standards as used with the ICF is essential. This is why the work on an ICF Ontology (defining classification entities with their attributes and value sets) is regarded as a priority for future ICF development.
The Structure of the ICF
As shown in Figure 11-1, the ICF is organized into two parts. Part 1 classifies functioning and disability formulated in two
components: (a) body functions and structures and (b) activities and participation. Part 2 comprises the contextual factors which include the following two components: (a) Environmental factors and (b) Personal factors (currently not classified).
components: (a) body functions and structures and (b) activities and participation. Part 2 comprises the contextual factors which include the following two components: (a) Environmental factors and (b) Personal factors (currently not classified).
 FIGURE 11-1. The model of functioning and disability on which the ICF is based. |
Definitions of some of the key terms used in ICF are given below.
Health condition is an umbrella term for disease (acute or chronic), disorder, injury, or trauma. A health condition may also include other circumstances such as pregnancy, ageing, stress, congenital anomaly, or genetic predisposition. Health conditions are coded using ICD-10.
Functioning is an umbrella term for body functions, body structures, activities, and participation. It denotes the positive aspects of the interaction between an individual (with a health condition) and that of an individual’s contextual factors (environmental and personal factors).
Disability is an umbrella term for impairments, activity limitations, and participation restrictions. It denotes the negative aspects of the ICF that provides a detailed classification with definitions: body functions are the physiological functions of body systems (including psychological functions); body structures are anatomical parts of the body such as organs, limbs, and their components; activity is the execution of a task or action by an individual; participation is involvement in a life situation; environmental factors make up the physical, social, and attitudinal environment in which people live and conduct their lives.
 FIGURE 11-2. The structure of the ICF and the distribution of the ICF’s 1,424 categories across its four components and four levels of hierarchy. |
The component of body functions and structures refers to physiological functions and anatomic parts of the body system, respectively; loss or deviations from normal body functions and structures are referred to as impairments. The second component of activities and participation refers to a single list of life domains (from basic learning or walking to composite areas like interpersonal relationships or employment). The component can be used to denote activities or participation or both. “Activity limitations” are thus difficulties the individual may have in executing activities (7). “Participation restrictions” are thus problems the individual may experience with such involvement (7). The components of body functions and structures and activity and participation are related to and may interact with the health condition (e.g., disorder or disease) and contextual factors.
Contextual factors include the components of environmental factors and personal factors. Since in the current ICF, an individual’s functioning and disability occurs in a context, ICF also includes a classification of environmental factors. The components of body functions and structures, activities and participation, and environmental factors are classified based on ICF categories. It is conceivable that a list of personal factors will be developed over the next years. The ICF contains a total of 1,495 meaningful and discrete or mutually exclusive categories. Taken together, the ICF categories are cumulative exhaustive and hence cover the whole spectrum of the human functioning. The categories are organized within a hierarchically nested structure with up to four different levels as shown in Figure 11-2. The ICF categories are denoted by unique alphanumeric codes with which it is possible to classify functioning and disability, both on the individual and population level.
TABLE 11.1 Examples of ICF Categories with their Corresponding Code, Title, and Definition | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
An example of the hierarchically nested structure is as follows: “b1 Mental functions” (first/chapter level); “b130 Energy and drive functions” (second level); and “b1301 Motivation” (third level). Based on the hierarchically nested structure of the ICF categories, a higher-level category shares the attributes of the lower-level categories to which it belongs. In our example, the use of a higher-level category (b1301 Motivation) automatically implies that the lower-level category is applicable (b130 Energy and drive functions).
Because the ICF categories are always accompanied by a short definition and inclusions and exclusions, the information on aspects of functioning can be reported unambiguously. Examples of ICF categories, with their definitions, inclusions, and exclusions are shown in Table 11-1.
ICF-BASED CLASSIFICATION AND MEASUREMENT OF FUNCTIONING
ICF Categories: Building Blocks and Reference Units
ICF categories with their definitions are the discrete, meaningful, and universally shared and understood entities, which allow users to comprehensively classify functioning of individuals and populations.
Qualifiers allow us to indicate the functioning level in a particular category. In the case of the component of environmental factors, they show the degree of positive or negative impact of environmental factors on the individual’s functioning. A most simple rule is binary coding. It assigns a “0” if a functioning problem is not present and “1” if it is present. A slightly more complex coding rule would be to assign a “0” if a functioning problem is not present, a “1” if it is somewhat present and “2” if a functioning problem is fully present. All three components classified in the ICF (body functions and structures, activities and participation, and environmental factors) are quantified using the same generic five-point scale. (“0” = no problem, “1” = mild problem, “2” = moderate problem, “3” = severe problem, “4”= complete problem). The qualifiers for the categories for the activities and participation component are capacity and performance. The qualifiers for the environmental factor categories are facilitators and barriers.
In general, coding based on specified rules is a form of measurement. According to Nunnally (33), measurement is the assignment of numbers to attributes, which represent particular features of an entity. In the specific case of the ICF, coding of the ICF qualifier, therefore, is a form of measurement since
it involves the assignment of numbers to attributes of ICF categories.
it involves the assignment of numbers to attributes of ICF categories.
Beyond coding, it is possible to measure attributes based on a scaling model using a scale. An example is the use of a visual analogue scale (scale) based on a metric model (scaling model) for the measurement of intensity of pain (attribute) in relation to pain (ICF category b280). Another example is the use of a self-administered questionnaire (scale) based on a RASCH model (scaling model) for the measurement of a capacity limitation (attribute) in walking (ICF category d450). The advantage of using a scale over coding is the possibility to place a person or a so-called stimulus on a continuum as defined by a suitable scaling model. A RASCH-based scale allows us to place a person on a continuum in relation to the experience of other persons (the population). It also allows us to place, for example, a questionnaire item (a stimulus) on the continuum in relation to any other item (e.g., items included in item banks) representing this attribute of an ICF category.
Based on this understanding, it becomes clear that ICF categories serve as building blocks for both the classification and measurement of human functioning. It also becomes clear how ICF categories are distinct from measurement items. ICF categories represent meaningful and universally shared entities. Conversely, items are stimuli, which allow the quantification of attributes in relation to these entities. Different from the limited number of ICF categories constituting cumulative exhaustive entities of the human experience represented in the ICF, there are a virtually infinite number of measurement items conceivable.
Therefore, ICF categories are the building blocks for the construction of ICF-based tools such as the ICF checklist (34) and the ICF Core Sets (35, 36, 37, 38) as well as clinical measurement instruments such as the ICF Core Set Index currently under development for Ankylosing Spondylitis (39) and generic health status measurement instruments such as the WHO Disability Assessment Schedule 2.0 (WHODAS 2.0) (40, 41, 42, 43).
ICF-Based Practical Tools: ICF Checklist, ICF Core Sets, and WHODAS 2.0
The ICF classification system contains 1,495 categories. “A clinician cannot easily take the main volume of the ICF and consistently apply it to his or her patients. In daily practice, clinicians will only need a fraction of the categories found in the ICF” (42). Therefore, “to be useful, ICF-based tools need to be tailored to the need of the prospective users without forgoing the information needed for health statistics and health reporting” (42). In response to this need, WHO and a wide range of partners including ISPRM have been collaborating in the development and promotion of ICF-based tools.
ICF Checklist
The ICF checklist provides a user-friendly display of the most relevant ICF categories and allows the user to identify and qualify the individual’s functioning profile in a simple but comprehensive and time efficient manner. The inclusion of diagnostic information in the checklist enables the user to study the relationship between a health condition and the associated functioning problems. The listing of environmental codes and the possibility to record information on personal factors permits the user to document and understand the impact of contextual factors on the person’s functioning.
The ICF checklist has been applied in a wide range of surveys and in studies in the process of developing ICF Core Sets (Table 11-2). As a generic tool for recording and documenting an ICF-based functioning profile, the checklist has a proved utility and feasibility (44, 45, 46). In situations where more detailed functional status information is needed, the ICF checklist was found to be too generic and the need for more condition- or setting-specific ICF tools (e.g., ICF Core Sets) was noted (47, 48).
ICF Core Sets
The ICF Core Set Project
The goal of the ICF Core Set project is to systematically develop parsimonious and hence practical sets of ICF categories for clinical practice, service provision, and research and to link the ICF to health conditions as coded with the ICD (35, 38, 42). The ICF Core Sets serve first as tools for the documentation of functioning and second as international reference standards for the reporting of functioning (7), irrespective of which measurement instruments were used. They are also the starting point for the development of clinical and self-reported measurement instruments (39, 49, 50).
The ICF Core Set Project is a joint project of the ICF Research Branch of the WHO FIC CC Germany (DIMDI) at the Institute of Health and Rehabilitation Sciences at the Ludwig-Maximilian-University in Munich, Germany (http://www.ICF-research-branch.org), together with WHO, ISPRM and a large number of partner organizations and associated institutions as well as committed clinicians and scientists (35, 38, 42).
Conceptual Approach
The conceptual approach for the development of the ICF Core Sets was derived from two perspectives: (a) the perspective of people who share the experience of the same condition (e.g., multiple sclerosis) or condition group (e.g., neurological conditions) and (b) the perspective of the health service context along the continuum of care and the life span.
ICF Core Sets for the Acute Hospital and (Early) Post-acute Rehabilitation Facilities
The ICF Core Sets for the Acute Hospital including the ICF Core Sets for neurological, cardiopulmonary, and musculoskeletal conditions are intended for use by physicians, nurses, therapists, and other health professionals not specialized in rehabilitation care provision (37, 38). By contrast, the ICF Core Sets for (early) post-acute rehabilitation facilities including the ICF Core Sets for neurological, cardiopulmonary, and musculoskeletal conditions as well as the ICF Core Set for geriatric patients are intended for use by physicians, nurses, therapists, and other health professionals specialized in rehabilitation or geriatric care provision (37, 38). The use of the term early indicates the early part of rehabilitation where patients have both medical needs requiring hospital care and rehabilitation needs.
TABLE 11.2 ICF Core Set Development | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
