Skip to 0 minutes and 12 secondsISLAY MACTAGGART: In the last step we started to discuss impairments and disability from the perspective of health care professionals. We started thinking about how impairment is only one component of disability-- but that it is an important part of the overall disability experience. This step will try to answer the question-- what are the most common impairments related to disability around the world? In particular, we will consider what is known about visual, hearing, and physical impairment, as well as mental health conditions and intellectual impairment. The first thing to flag is that unfortunately, there is not really enough global data to answer this question in full.

Skip to 0 minutes and 53 secondsSo now we're going to take a look at what we do know about the different impairments that I mentioned above.

Skip to 1 minute and 0 secondsWe do know quite a lot about visual impairment, which is generally measured with vision charts, with people classified based on how well they can see. This picture shows a woman undergoing a vision test outside her home in Mexico, using a simple vision chart called a Tumbling E. Looking across the global data, the International Agency for the Prevention of Blindness estimates that around the world 253 million people are visually impaired, of whom 36 million are blind.

Skip to 1 minute and 32 secondsCommon causes of visual impairment and blindness include cataract and uncorrected refractive error. Although the rise in diabetes is also increasing the risk of blindness from diabetic retinopathy in many parts of the world. There are also some estimates on the magnitude of hearing impairment, which is measured in terms of how well people can hear noises at different frequencies. This picture shows a participant in India wearing noise cancelling headphones, whilst having her hearing tested using a field audiometer. The World Health Organisation estimates that 5.3% of the world's population-- 360 million people-- experience disabling hearing loss. Hearing loss is often related to ageing, with one in three people over 65 expected to experience disabling hearing loss.

Skip to 2 minutes and 22 secondsIt can also be congenital, for example, related to low birth weight or maternal infections during pregnancy. Or acquired through infections or noise exposure.

Skip to 2 minutes and 36 secondsThe difficulty in working out how common physical impairments are, is that they include lots of different conditions that manifest in different ways. For example, everything from missing digits to quadriplegia. It is therefore difficult to have common measures of these conditions, and to produce global estimates. However, we do know that physical impairment is common, particularly in low and middle income countries. For example, the International Centre for Evidence in Disability recently developed a rapid assessment tool for physical impairment. We completed three surveys in Rwanda, Cameroon, and India using this tool. We found that 5.2% of the population in Rwanda, 3.4% of the population in Cameroon, and 3.5% of the population in India had a moderate or worse physical impairment.

Skip to 3 minutes and 28 secondsMost of the physical impairment was related to ageing, often as a result of joint pain or deterioration, followed by trauma and neurological conditions such as paraplegia.

Skip to 3 minutes and 41 secondsThe problem is similar for estimating the magnitude of impairment related to mental health conditions. These can include depression, schizophrenia, or intellectual impairments, and so are impossible to measure on a single scale. We do know, however, that these conditions are not rare. Analysis from 17 World Health Organisation's World Mental Health surveys of adults found that between 1 and 3, or 1 in 4 people worldwide experience mental disorder over the course of their lifetime. And the most recent 2015 estimates from the global burden of diseases shows us that around 153 million people worldwide have an intellectual impairment. So as we can see, we don't have a lot of global-level data on the most common impairments related to disability.

Skip to 4 minutes and 30 secondsBut we can see that vision, hearing, physical impairment, intellectual impairment, and mental health conditions all affect lots of people around the world. It's important that we have and build on this information to help us plan how best health and rehabilitation services can support people with disabilities, both in terms of their impairments, and their broader needs.

What are the common impairments related to disability?

Activity 3 provided us with an introduction into how disability is conceptualised in global health, including the importance of differentiating between the individual’s impairment, or health condition, and their broader function and participation in society - or disability.

Our last activity this week will focus on what we know about the common impairments related to disability, so that we can continue thinking about how to support health and wellbeing for people with disabilities in different ways.

In this step, Dr. Islay Mactaggart (LSHTM) presents the common impairments related to disability according to the best available data that we have.

Let us know in the comments whether you were surprised by any of the findings, and how they compare to your own experiences in your own context. Please remember not to reveal any confidential information when posting your comments.

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This video is from the free online course:

Global Health and Disability

London School of Hygiene & Tropical Medicine