Disability is an umbrella term for impairments, limitations in performing activities, and restrictions in participation in everyday life. It arises through interactions between a person’s health condition and environmental and personal factors, rather than being determined by a medical condition alone. Disability can affect movement, vision, hearing, cognition, communication, or mental functioning. Its extent and consequences vary between individuals, including those with the same condition, and some disabilities are not readily visible. (who.int)
Definition and classification
The World Health Organization (WHO) organizes the description of functioning and disability through the International Classification of Functioning, Disability and Health (ICF). Endorsed on May 22, 2001, the ICF provides a common framework for describing body functions and structures, activities, participation, and environmental influences at individual and population levels. Its framework places functioning within the circumstances in which a person lives. (who.int)
Three interconnected dimensions are commonly distinguished:
- Impairment: a significant difference or loss in body structure, bodily function, or mental functioning, such as loss of a limb or reduced vision.
- Activity limitation: difficulty executing a task, such as walking, reading, remembering information, or solving a problem.
- Participation restriction: difficulty taking part in a life situation, such as employment, education, relationships, or community activities.
These dimensions describe different aspects of functioning. The distinction between activity and participation is not always sharp, and the ICF combines them within one component. Environmental factors—including technology, social support, services, policies, and attitudes—can facilitate functioning or create barriers. (cdc.gov)
Diversity and development across life
Disability is not a single condition or a uniform experience. Functional difficulties may involve physical, sensory, cognitive, learning, communication, or mental health domains. Individuals may experience difficulties in several domains simultaneously. A condition’s name does not, by itself, describe the full range of a person’s abilities, activities, or support needs. (cdc.gov)
Disability may be associated with conditions present at birth, developmental conditions, injuries, or conditions acquired later in life. Some health conditions progressively affect functioning, while others produce difficulties that may change over time. Examples of conditions associated with disability include spinal cord injury, blindness, and dementia. WHO attributes growth in the global number of people experiencing disability partly to longer lives and increasing noncommunicable diseases. (cdc.gov)
Population measurement
In its March 7, 2023 fact sheet, WHO estimated that approximately 1.3 billion people, or 16% of the world’s population, experienced significant disability. This estimate describes a diverse population whose experiences differ with age, economic circumstances, and other personal and social factors. (who.int)
Measuring disability requires specifying which aspects of functioning are being assessed. The Washington Group on Disability Statistics develops survey instruments intended to support international comparison. Its Short Set covers six domains: seeing, hearing, walking or climbing steps, remembering or concentrating, self-care, and communication. Estimates can change when questions or domains are omitted; consequently, a reported prevalence figure must be interpreted in relation to its measurement method. (washingtongroup-disability.com)
The Washington Group’s Enhanced Short Set adds questions concerning upper-body functioning and anxiety and depression. Different instruments therefore capture different ranges of functional difficulty, rather than providing interchangeable descriptions of disability. (washingtongroup-disability.com)
Environmental barriers and accessibility
Accessibility concerns whether environments, information, and services can be used by people with differing functional requirements. Barriers include stairs and curbs, inaccessible transportation, information presented only in formats that some people cannot use, and policies or attitudes that restrict participation. Websites incompatible with screen readers illustrate how a communication barrier can limit access without any change in an individual’s impairment. (cdc.gov)
Universal design seeks to make environments and products usable by a broad range of people. Individual accommodations modify an existing environment or process to enable participation. Accessible communication can involve sign language, Braille, captions, or other formats suited to particular requirements. These approaches address different barriers and may be used together. (cdc.gov)
Health services and support
Disability is relevant to public health because people with disabilities can encounter unequal access to health information, transportation, facilities, and services. WHO identifies poverty, discrimination, exclusion from education and employment, and barriers within the health system as contributors to health inequities. These factors form part of the social determinants of health, rather than being consequences of impairment alone. (who.int)
Rehabilitation comprises interventions intended to optimize functioning in the interaction between a person and their environment. It can include support for mobility, communication, cognition, and everyday activities. Assistive technology includes products and related services that maintain or improve functioning: examples include wheelchairs, hearing aids, prostheses, and digital communication tools. Rehabilitation and assistive technology are relevant to universal health coverage, although access remains uneven between and within countries. (who.int)
International rights framework
The United Nations adopted the Convention on the Rights of Persons with Disabilities on December 13, 2006; it entered into force on May 3, 2008. The treaty provides an international human rights framework centered on persons with disabilities as rights-holders and participants in society, rather than solely as recipients of charity, treatment, or social protection. The UN’s account emphasizes decision-making, active participation, and free and informed consent as elements of this approach. (un.org)