Disability is part of the human condition. Almost everybody will be temporarily or permanently impaired at some point in life, and those who survive to old age will experience increasing difficulties in functioning. Most extended families have a disabled member, and many non-disabled people take responsibility for supporting and caring for their relatives and friends with disabilities. People with disabilities may require a range of services – from relatively minor and inexpensive interventions to complex and costly ones. Unmet needs for support may relate to everyday activities. The economic and social costs of disability are significant, but difficult to quantify. They include direct and indirect costs, some borne by people with disabilities and their families and friends and employers, and some by society.  Many of these costs arise because of inaccessible environments and could be reduced in a more inclusive setting. Knowing the cost of disability is important not only for making a case for investment, but also for the design of public programs. Comprehensive estimates of the cost of disability are scarce and fragmented, even in developed countries. Nearly all countries have some type of public programs targeted at persons with disabilities, but in poorer countries these are often restricted to those with the most significant difficulties in functioning. [1]

Many people with disabilities do not have equal access to health care, education, and employment opportunities, do not receive the disability-related services that they require, experience exclusion from everyday life activities, and experience worse socioeconomic outcomes and poverty than persons without disabilities. Despite the magnitude of the issue, both awareness of and scientific information on disability issues are lacking. There is no agreement on definitions and little internationally comparable information on the incidence, distribution and trends of disability. The disability experience resulting from the interaction of health conditions, personal factors, and environmental factors varies greatly. Disability encompasses the child born with a congenital condition such as cerebral palsy or the young soldier who loses his leg to a land-mine, or the middle-aged woman with severe arthritis, or the older person with dementia, among many others. Health conditions can be visible or invisible; temporary or long term; static, episodic, or degenerating; painful or inconsequential. Many people with disabilities do not consider themselves to be unhealthy. [1]

One billion people, or 15% of the world’s population, experience some form of disability, and disability prevalence is higher for developing countries. One-fifth of the estimated global total, or between 110 million and 190 million people, experience significant disabilities. The prevalence estimates presented here should be taken not as definitive but as reflecting current knowledge and available data. Approaches to measuring disability vary across countries and influence the results. Disability can be conceptualized on a continuum from minor difficulties in functioning to major impacts on a person’s life in relation to what is considered normal functioning, which can vary based on the context, age group, or even income group, and is not a blank yes or no answer. There have been attempts in recent years to standardize disability surveys, But the definitions and methodologies used vary so greatly between countries that international comparisons still remain difficult. [1]

National survey and census data cannot be compared directly with the World Health Survey or Global Burden of Disease estimates, because there is no consistent approach across countries to disability definitions and survey questions. The overall prevalence rates from both the World Health Survey and Global Burden of Disease analyses are determined by the thresholds chosen for disability. Different choices of thresholds result in different overall prevalence rates, even if fairly similar approaches are used in setting the threshold. This methodological point needs to be borne in mind when considering these new estimates of global prevalence. While the prevalence data in this Report draw on the best available global data sets, they are not definitive estimates. There is an urgent need for more robust, comparable, and complete data collection. [1]

The relationship between health conditions and disabilities is complicated. Whether a health condition, interacting with contextual factors, will result in disability is determined by interrelated factors. It is not possible to produce definitive global statistics on the relationship between disability and health conditions. Studies that try to correlate health conditions and disability without taking into account environmental effects are likely to be deficient. [1]

Road traffic injury, occupational injury, violence, and humanitarian crises have long been recognized as contributors to disability. However, data on the magnitude of their contribution are very limited. Prevalence estimates of post-crash disability varied from 2% to 87%, largely a result of the methodological difficulties in measuring the non-fatal outcomes following injuries. [1]

A person’s environment has a huge impact on the types of obstacles they have to overcome: judgment without being spoken to, unable to exist and do daily tasks comfortably, limited physical access of schools, parks, shops, and homes, a deaf individual without a sign language interpreter, a blind person using a website that cannot be used with a screen reading software, unsafe water and sanitary conditions. Environmental factors include a wider set of issues than simply physical and information access. Policies and service delivery systems, including the rules underlying service provision, can also be obstacles. Children bullying other children with disabilities in schools, bus drivers failing to support access needs of passengers with disabilities, employers discriminating against people with disabilities, and strangers mocking people with disabilities. [1]

Medical equipment is often not accessible for people with disabilities, particularly those with mobility impairments. Many women with mobility impairments are unable to access breast and cervical cancer screening because examination tables are not height-adjustable and mammography equipment only accommodates women who are able to stand. [1]

Service providers may feel uncomfortable communicating with people with disabilities, such as health-care workers often turning their heads down when talking, preventing deaf people from lip-reading. Many health-care providers have not been trained to interact with people with serious mental illness, and feel uncomfortable or ineffective in communicating with them. [1]

There is a higher risk of disability at older ages, and national populations are aging at unprecedented rates. Disability is associated with a diverse range of primary health conditions: some may result in high health care needs; others keep people with disabilities from achieving good health. [1]

All groups in society should have access to comprehensive, inclusive health care: [1]

Accessibility – Stop discrimination against people with disabilities when accessing health care, health services, food or fluid, health insurance, and life insurance. This includes making the environment accessible.
Affordability – Ensure that people with disabilities get the same variety, quality, and standard of free and affordable health care as other people.
Availability – Put early intervention and treatment services as close as possible to where people live in their communities.
Quality – Ensure that health workers give the same quality care to people with disabilities as to others.

How environments can be changed: [1]
1. Accessible design of the built environment and transport;
2. Signage to benefit people with sensory impairments;
3. More accessible health, rehabilitation, education, and support services;
4. More opportunities for work and employment for persons with disabilities.

Laws about disability have been around for centuries, with the 1st U.S. pension law given to injured soldiers in 1776. The Americans with Disabilities Act of 1990 (ada) is a federal American civil rights law that prohibits discrimination based on disability. This was the 1st major piece of national legislation in the world to systematically address the discrimination, barriers, and challenges faced by people with disabilities. Other countries followed suit by adopting similar ADA principles. [2]

ADA disabilities include both mental and physical medical conditions. A condition does not need to be severe or permanent to be a disability. [3] United States Equal Employment Opportunity Commission regulations provide a list of conditions that should easily be concluded to be disabilities: 

Deafness, 
Blindness, 
An intellectual disability,
Amputations,
Mobility impairments requiring the use of a wheelchair or other assistive devices,
Autism,
Cancer,
Cerebral Palsy,
Diabetes,
Down Syndrome
Epilepsy,
Attention Deficit Hyperactivity Disorder (ADHD),
Human Immunodeficiency Virus (HIV) Infection,
Multiple Sclerosis,
Muscular Dystrophy,
Major Depressive Disorder,
Bipolar Disorder,
Post-Traumatic Stress Disorder,
Obsessive Compulsive Disorder (OCD),
and Schizophrenia. 

Other mental or physical health conditions also may be disabilities, depending on what the individual's symptoms would be in the absence of "mitigating measures'' (medication, therapy, assistive devices, or other means of restoring function), during an "active episode" of the condition (if the condition is episodic). [4]

In 1986, the National Council on Disability (NCD), an independent U.S. federal agency, issued a report that identified the large remaining gaps in the U.S civil rights coverage for people with disabilities which recommended the adoption of comprehensive civil rights legislation, which became the ADA. [5]

Shortly before the act was passed, disability rights activists went in front of the U.S. Capitol Building, shed their crutches, wheelchairs, powerchairs and other assistive devices, and immediately proceeded to crawl and pull their bodies up all 100 of the Capitol's front steps, without warning. [6] As the activists did so, many of them chanted "ADA now", and "Vote, now". Jennifer Keelan, a second grader with cerebral palsy, was videotaped as she pulled herself up the steps, using mostly her hands and arms, saying "I'll take all night if I have to." This direct action is reported to have "inconvenienced" several senators and to have pushed them to approve the act. While there are those who do not attribute much overall importance to this action, the "Capitol Crawl" of 1990 is seen by some present-day disability activists in the United States as a central act for encouraging the ADA into law. [7]

1. Afghanistan
2. Albania
3. Algeria
4. Andorra
5. Angola
6. Antigua and Barbuda
7. Argentina
8. Armenia
9. Australia
10. Austria
11. Azerbaijan
12. Bahamas
13. Bahrain
14. Bangladesh
15. Belarus
16. Belgium
17. Bolivia
18. Bosnia and Herzegovina
19. Brazil
20. Brunei Darussalam
21. Bulgaria
22. Burkina Faso
23. Cambodia
24. Cameroon
25. Canada

26. Chad
27. Chile
28. China
29. Colombia
30. Cook Islands
31. Costa Rica
32. Croatia
33. Dominican Republic
34. Ecuador
35. El Salvador
36. Ethiopia
37. Fiji
38. Finland
39. France
40. Gabon
41. Georgia
42. Germany
43. Ghana
44. Guatemala
45. Haiti
46. Honduras
47. Hong Kong
48. Hungary
49. India
50. Indonesia

51. Iran
52. Iraq
53. Israel
54. Italy
55. Jamaica
56. Japan
57. Jordan
58. Kazakhstan
59. Kenya
60. Korea (North)
61. Korea (South)
62. Latvia
63. Lithuania
64. Luxemburg
65. Macau
66.Malaysia
67. Malawi
68. Maldives
69. Malta
70. Marshall Islands
71. Mauritius
72. Mexico
73. Monaco
74. Mongolia
75. Montenegro

76. Myanmar
77. Nepal
78. Netherlands
79. New Zealand
80. Nicaragua
81. Niger
82. Nigeria
83. Norway
84. Oman
85. Palau
86. Panama
87. Paraguay
88. Peru
89. Philippines
90. Poland
91. Portugal
92. Qatar
93. Republic of Moldova
94. Republic of North Macedonia
95. Romania
96. Russian Federation
97. Rwanda
98. Saudi Arabia
99. Senegal
100. Serbia

101. Sierra Leone
102. Slovenia
103. South Africa
104. Spain
105. Sri Lanka
106. Sudan
107. Sweden
108. Switzerland
109. Tanzania
110. Thailand
111. Togo
112. Trinidad and Tobago
113. Tunisia
114. Turkey
115. Uganda
116. Ukraine
117. United Arab Emirates
118. United Kingdom
119. United States
120. Uruguay
121. Venezuela
122. Viet Nam

A lack of data and research evidence can create a significant barrier for policy-makers and decision-makers, which in turn can influence the ability of people with disabilities to access mainstream health services. Improving disability data may be a long-term enterprise, but it will provide essential underpinning for enhanced functioning of individuals, communities and nations. [1]

[6] J. Eaton, W. “Disabled Persons Rally, Crawl Up Capitol Steps.” Los Angeles Times. Link

[8] “Disability Laws and Acts by Country/Area Enable.” United Nations. Link

[4] "Regulations to Implement the Equal Employment Provisions." Equal Employment Opportunity Commission. Link

[7] Mickiewicz, D. "The Capitol Crawl." Boundary Stones. Link

[2] "The ADA Legacy Project: Moments in Disability History 24: ADA's International Impact." The Minnesota Governor's Council on Developmental Disabilities. Link

[5] “The Presidential Timeline.” Presidential Timeline. Link

[3] U.S. Equal Employment Opportunity Commission. “Fact Sheet on the EEOC's Final Regulations Implementing the ADAAA.” U.S. Equal Employment Opportunity Commission. Link

[1] World Report on Disability - World Health Organization. Link