Author(s): Nitin B. Jain, MD, MSPH, Kindred Harris, MD
Originally published: September 20, 2014 Last updated: June 19, 2024
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Overview and Description

Introduction

The term “disability” has different connotations depending on the individual, context, and setting. The US Department of Justice takes a legal approach to define disability under the Americans with Disabilities Act,1 as does the Social Security Administration.2 The rehabilitation approach to disability integrates many concepts using the World Health Organization International Classification of Functioning, Disability and Health (ICF) model.3 Some of these perspectives are presented in Table 1. To understand the diverse definitions of disability, it is useful to examine the conceptual models formulated over time by stakeholder perspectives. Stakeholders include but are not limited to individuals with a disability, advocates, family members, healthcare providers, researchers, educators, employers, legal advocates, government organizations, non-governmental agencies, the labor industry, architects and engineers, individual consultants, religious leaders, cultural leaders, and community members.

Conceptual-Models-of-Disability-Table-1

Disabilities can be “visible” (e.g., a limb amputee) and/or “invisible” (e.g., a chronic illness such as diabetes). Further, symptoms and impairments can be episodic or continuous, static or progressive, acute or chronic, congenital, or occur at any time point during a person’s lifespan. Disabilities can be attributed to genetics, biology, injury, and/or environmental factors.4 Finally, only recently have mental illnesses been included under the umbrella of disability and have been given more justice about rights and accommodations.4

Conceptual Models of Disability

Conceptual models of disabilities can be used to further define disability and understand the impact of the disability on function. While there are many models of disability, two categories stand at the ends of the spectrum – the “individual” or “medical” model where disability is seen as an attribute of an individual health condition, and the “social” model, where disability is a product of one’s environment.5 There are many additional models of disabilities, such as the biopsychosocial model or intersectional models, that focus on combining elements from previous or other models (Table 2). Further, many models of disability have been applied practically in the context of specific conditions such as neurodiversity.

Conceptual-Models-of-Disability-Table-2

Medical Models of Disability

Healthcare, medical education, and research on disabilities are dominated by a medical model. Medical models of disability equate pathology with inherent disability. For example, both a person with paraplegia and deafness are considered disabled. By definition of the medical model, a person is disabled only by being compared to a more normal functioning organ or body system that is usually venerated, readily acceptable, and easily integrated into current society.6 Thus, the bodies of individuals with disabilities are the cause of their dissolution from societal participation, including experiencing inequitable housing, healthcare, education, employment, and human rights.6 Disability is viewed as a defect that medicine and healthcare professionals must fix. This contributes to stigmatization, impoverishment, and institutionalization of individuals with disabilities.7

Further, ableism—discrimination and social prejudice against people with disabilities, was born out of the medical model of disability. Brinkman et al notes that previous euphemisms such as handicap, challenged, special needs, or differently able can lead to shame, as this naturally distances an individual with a disability from an able individual.4 Thus, many advocates are proponents of person-first language, such as a man with diabetes versus a diabetic man. In the previous sentence, the man, an individual is presented first. However, many individuals with disabilities find advocacy and power in utilizing an identify first language, where the identifier is their disability. For instance, many individuals with diabetes still refer to themselves as a “diabetic,” as this allows others such as healthcare providers to immediately become aware of associated factors, such as the need to check and aggressively treat lower extremity wounds to reduce the risk of lower extremity amputations. Further, euphemisms, identity, and belonging can also be regional and cultural. In the southern United States, diabetes is colloquially called “sugar” by all. An individual may say “I have sugar,” versus “no thank you” to an offer of a sweet dessert. This case may be an example of a novel term—identity-focused language. Overall, identity first or identity-focused language allows individuals with identities to more easily identify each other, seek out support, and join specific disability communities.4

Social Models of Disability

Social models of disability frame disability in an environmental context. Mike Oliver, a pioneer of the social model in the 1980s, based the social model on his belief that individual limitations are not the cause of the problem. Rather, it is society’s failure to provide appropriate services and adequately ensure that the needs of disabled people are considered in societal organization.8 For example, a person with hearing loss is not disabled by the hearing loss itself, but by the environment not providing the appropriate resources for that person, such as a visual or written communication format or an interpreter. This type of model was pioneered mostly by individuals previously labeled as disabled by the medical model of disability who desired increased opportunities for self-advocacy and autonomy.

Biopsychosocial Models of Disability

Over time, it became clear that disability was neither a strictly medical nor social concept. The movement toward combining the concepts into biopsychosocial models started, developed initially by George Engel in the 1970s.9 In 1980, utilizing these concepts, the World Health Organization (WHO) released the International Classification of Impairments, Disabilities, and Handicaps (ICIDH) which classifies disability into three domains: impairment, disability, and handicap. Impairments were defined as abnormalities of body structure, appearance, or organ system dysfunction. Disabilities were defined as the consequences of impairments in terms of functional performance and activity of the individual. Handicaps were defined as the disadvantages experienced by the individual due to impairments and disabilities.10

The ICIDH was revised several times. Since 2002, it has been known as the International Classification of Functioning, Disability, and Health (ICF). Interim updates occur, most recently 2018.3 A companion classification for children and youth (ICF-CY) was published in 2007.11 The ICF examines the interaction of health conditions and contextual factors to define the spectrum of functioning and disability at the organ system, individual, and social levels. In this model, “functioning” is aimed at body structure and functions at the organ system level, activities at the individual level, and participation at the social level. Disability corresponds to impairment, activity limitation, and participation restriction. Contextual factors include internal personal factors and external environmental factors. The ICF emphasizes health and functioning rather than disability. The ICF is formulated to complement the medical coding system of the International Classification of Diseases 10th revision (ICD-10).12

Other Lenses and Viewpoints of Disability

Intersectionality

Originating from Black feminist literature, intersectionality describes ways systems of oppression lead to an individual’s unique life experience. Non-intersectional models of disabilities, such as the medical model, fail to consider that individuals with a disability hold other identifiers like race and gender that may put them into other differently advantaged categories and that overall are truly a combination of many different identifiers4 Individuals with disabilities may prefer to use their non-disability identifiers first, primarily, solely, or not at all; this varies with circumstances. Other identifiers can also compound challenges individuals with disabilities may face while receiving care or seeking resources, such as health inequity.4 For example, older Black Americans with disabilities in the United States were found to have higher odds ratios for cognitive dysfunction such as difficulty concentrating, functional limitations such as mobility, and difficulty with performing activities of daily living (ADLs) such as dressing compared to their white disabled counterparts. The disparity remained, though lower, even after adjustments for education and income.13 Thus, black individuals with disabilities may need earlier intervention, additional services, or more equitable access to services to reduce the disparity gap. Intersectional framework which more holistically assesses individuals can help identify and reduce health inequities.6 Despite the positive aspects of intersectional models of disabilities, they have not been universally adopted.4 Most individuals with and without disabilities hope to have freedom and flexibility in defining themselves in a way that is helpful, meaningful, and prideful to them.6

Minority Stress Model

The minority stress model postulates that chronic, extreme, addictive societal-driven stress, such as failure to provide necessary accommodations for housing or employment, placed on minority populations may lead to negative consequences, such as health disparities.14 Lund uses the minority stress model to account for the increased risk of suicidality, independent of co-morbid depression and other sociodemographic factors, for individuals with disabilities. Though this demographic is one of the largest minority groups and encompasses over one-quarter of the United States population, the disability minority group is unique given its heterogeneity, which can lead to additional challenges, including some related to the disability itself, ranging from inability to communicate to disagreements regarding disability nomenclature.14

Neurodivergence

There are also new categories specific to certain disabilities, such as the concept of neurodivergence. Neurodiversity suggests that variations in the human brain and behavior are natural and valid ways of being. It suggests attitudes and barriers imposed by society cause impairment rather than differences in brain development or behavior. Definition-wise, the neurodiversity concept stating individuals are simply different but remain within a normative range prompts ongoing acceptance versus cure debates”.6 For example, Wright Stein et al question if autism spectrum disorder (ASD) is “a pathology to be cured, a form of social exclusion, a natural variation in abilities, or something else” entirely.15 Proclaiming autism as a normal variation may lead to less stigma and more social acceptance for individuals with autism. However, this may come with a heavy cost—the possible loss of already scarce and tenuous government funding for rehabilitation and other resources allocated for individuals with a medical diagnosis of autism.15 Further, this may disproportionately affect individuals who are non-high functioning (more dependent for needs with more severe functional impairments in society) with significant impairments.15

Overall, it is important to note that all models and concepts of disabilities have applications for quantitative and qualitative assessment of disability and functioning, informing individual and communal needs and resources, monitoring costs, directing social policy, and maximizing awareness and acceptance globally.

Current Concepts

Applications of ICF

The common language of rehabilitation

The ICF offers a common language at multiple levels, including the individual, institutional, and social levels. The ICF focuses on three components, each with hierarchal domains and qualifiers, which together display what areas, what contributing factors, and to what extent is functioning limited due to disability.11 For example, capacity and performance are used in portions of the assessment to assess environmental influences on function. Capacity looks at an individual in a standard or clinical environment, such as a rehabilitation hospital whereas performance looks at an individual in their usual or a natural environment, such as their group home.11 Last, the ICF is strictly limited to health, not social justice factors such as gender or racial prejudice.11

The ICF is not without limitations. Some recommendations for improvement include the evaluation of categorical mutual exclusivity, further distinguishment between elements of activity and participation, addition of quality-of-life concepts, and expansion of contextual and personal factors.16,17

Defining rehabilitation strategy

The ICF has been used to define rehabilitation as a “health strategy that “applies and integrates approaches” rooted in concepts of functioning, contextual factors, capacity, performance, person-provider partnership, and self-perception. It maps a health condition course through the continuums of care and across sectors to optimize functioning.18

Developing clinical tools

The World Health Organization Disability Assessment Schedule 2.0 (WHODAS-2) was created in 1998 as WHODAS II in line with the ICF conceptual model and to be used in assessing disability based on this model.19

There are 36 items (self-administered and covering the past 30 days) on functioning and disability covering seven domains under WHODAS-2, which are the following (and explicit):

  • Understanding and Communicating (6 items)
  • Getting around (5 items)
  • Self-care (4 items)
  • Getting along with others (5 items)
  • Life activities: Household (4 items)
  • Life activities: Work/School (4 items)
  • Participation in society (8 items)

For each item, the response is scored as 1 (no difficulty), 2 (mild difficulty), 3 (moderate difficulty), 4 (severe difficulty), or 5 (extreme difficulty or cannot do), with scores for each domain based on item responses, with room for missing items up to 30% for each domain. A final score is then computed that fits into a range from 0 to 100, with higher scores indicating greater disability. Health conditions are disabilities within each domain. Having difficulty with an activity means increased effort, discomfort or pain, slowness, or changes in the ways activities are performed.

Finally, a “Rehabilitation Problem-Solving Form,” was developed as a visual representation of aspects of pathology and relationships among disabilities and underlying factors for interdisciplinary team meetings to discuss interventions and their goals.20

From a global perspective, “the prevalence of health conditions associated with severe limitations in functioning increased by nearly 183 million between 2005 and 2017… Strengthening rehabilitation—the health strategy to optimize functioning—is therefore essential. Current estimates show that 2.4 billion persons have a health condition that benefits from rehabilitation; the unmet need for rehabilitation is profound… Currently, there is no health system assessment (HSA) tool for rehabilitation. The World Health Organization (WHO) thus initiated the development of the Systematic Assessment of Rehabilitation Situation (STARS) within the Rehabilitation 2030 initiative.”21

Conclusion

Conceptual models of disability lie on a spectrum between social and medical perspectives. The biopsychosocial models combine features of both and form the basis of the WHO ICF, which serves as the common language of rehabilitation and has further been used to define rehabilitation strategy. Each conceptual model of disability has advantages and disadvantages that vary based on the individual, context, and setting. The development of newer distinct intersectional conceptual models of disabilities is ongoing. Most people with disabilities have blended viewpoints and require an integrated approach for optimal function.15 It is vital for all stakeholders in rehabilitation to have a working knowledge of these models to appreciate the varying viewpoints and coordinate optimal rehabilitation care and resources for addressing disability.

References

  1. U.S. Department of Justice Civil Rights Division. Guide to Disability Rights Laws. ADA.gov. Published November 19, 2022. https://www.ada.gov/resources/disability-rights-guide/
  2. Part I – General Information. Ssa.gov. Published 2020. https://www.ssa.gov/disability/professionals/bluebook/general-info.htm
  3. World Health Organization. “International Classification of Functioning, Disability and Health (ICF).” World Health Organisation, 2001, www.who.int/standards/classifications/international-classification-of-functioning-disability-and-health.
  4. Brinkman AH, Rea-Sandin G, Lund EM, et al. Shifting the discourse on disability: Moving to an inclusive, intersectional focus. Am J Orthopsychiatry. 2023;93(1):50-62. doi:10.1037/ort0000653
  5. Marks D. Models of disability. Disabil Rehabil. 1997;19(3):85-91. doi:10.3109/09638289709166831
  6. Kover ST, Abbeduto L. Toward Equity in Research on Intellectual and Developmental Disabilities. Am J Intellect Dev Disabil. 2023;128(5):350-370. doi:10.1352/1944-7558-128.5.350
  7. Masala C, Petretto DR. Models of disability. In: JH Stone, M Blouin, eds. International Encyclopedia of Rehabilitation. 2010.
  8. Oliver, Mike. The Individual and Social Models of Disability. disability-studies.leeds.ac.uk/wp-content/uploads/sites/40/library/Oliver-in-soc-dis.pdf. Accessed 12 Apr. 2024.
  9. Engel GL. The need for a new medical model: a challenge for biomedicine. Science. 1977;196(4286):129-136. doi:10.1126/science.847460
  10. International Classification of Impairments, Disabilities, and Handicaps: A Manual of Classification Relating to the Consequences of Disease. Geneva: World Health Organization;1980. Published in Accordance with Resolution WHA 29.35 of the 29th World Health Assembly, May 1976.
  11. National Center for Health Statistics. “The ICF: An Overview.” Centers for Disease Control and Prevention, 2012.
  12. World Health Organisation. Towards a Common Language for Functioning, Disability and Health ICF towards a Common Language for Functioning, Disability and Health: ICF the International Classification of Functioning, Disability and Health. 2002.
  13. Shipeolu BA, Marie Ahlin K, Fuller-Thomson E. Black-White Racial Disparities in Disabilities Among Older Americans Between 2008 and 2017: Improvements in Cognitive Disabilities but no Progress in Activities of Daily Living or Functional Limitations. Int J Aging Hum Dev. 2024;98(1):84-102. doi:10.1177/00914150231196092
  14. Lund EM. Examining the potential applicability of the minority stress model for explaining suicidality in individuals with disabilities. Rehabil Psychol. 2021;66(2):183-191. doi:10.1037/rep0000378
  15. Wright Stein S, Alexander R, Mann J, et al. Understanding disability in healthcare: exploring the perceptions of parents of young people with autism spectrum disorder. Disabil Rehabil. 2022;44(19):5623-5630. doi:10.1080/09638288.2021.1948114
  16. Field, Marilyn J., et al. Workshop on Disability in America: A New Look – Summary and Background Papers. National Academies Press, Washington, D.C., National Academies Press, 27 Feb. 2006, nap.nationalacademies.org/catalog/11579/workshop-on-disability-in-america-a-new-look-summary-and. Accessed 13 Apr. 2024
  17. Cozzi S, Martinuzzi A, Della Mea V. Ontological modeling of the International Classification of Functioning, Disabilities and Health (ICF): Activities & Participation and Environmental Factors components. BMC Med Inform Decis Mak. 2021;21(1):367. Published 2021 Dec 29. doi:10.1186/s12911-021-01729-x
  18. Meyer T, Gutenbrunner C, Bickenbach J, Cieza A, Melvin J, Stucki G. Towards a conceptual description of rehabilitation as a health strategy. J Rehabil Med. 2011;43(9):765-769. doi:10.2340/16501977-0865
  19. “Measuring Health and Disability: Manual for WHO Disability Assessment Schedule (‎WHODAS 2.0)‎.” Www.who.int, 2010, www.who.int/publications/i/item/measuring-health-and-disability-manual-for-who-disability-assessment-schedule-(-whodas-2.0)
  20. Steiner WA, Ryser L, Huber E, Uebelhart D, Aeschlimann A, Stucki G. Use of the ICF model as a clinical problem-solving tool in physical therapy and rehabilitation medicine. Phys Ther. 2002;82(11):1098-1107.
  21. Kleinitz P, Sabariego C, Cieza A. Development of the WHO STARS: A Tool for the Systematic Assessment of Rehabilitation Situation. Arch Phys Med Rehabil. 2022;103(1):29-43. doi:10.1016/j.apmr.2021.04.025

Original Version of the Topic

Alycia Reppel, MD, Segun Dawodu, MD. Conceptual Models of Disability. 9/20/2014

Previous Revision(s) of the Topic

Prateek Grover MD PhD MHA. Conceptual Models of Disability. 3/11/2021

Author Disclosure

Nitin B. Jain, MD, MSPH
Nothing to Disclose

Kindred Harris, MD
Nothing to Disclose