Measuring impairments and disability (cont.)
Measuring impairments and health conditions
Measuring impairments and health conditions indicates a greater focus on a medical definition of disability. The measurement is often done by asking individuals to self-report on impairments (e.g. asking if they have an impairment and if so what), to report on earlier clinical diagnoses, or having a team of medical personnel conducting assessments as part of the study. Studies of this kind, in which a cause of impairment may be identified, are important for planning primary prevention strategies, and rehabilitation and treatment programmes.
This is problematic in low resource settings. People may not be able to access health care to obtain diagnoses due to a lack of resources or specialist doctors, and the cost of studies which involve medical personnel going door-to-door may be prohibitive. However costs may be reduced by using a screening questionnaire to identify those at greatest risk of disability, and then following those identified with visits from medical personnel.
The table below shows details of some commonly used measurement tools for impairments. This list is not comprehensive, but should give an idea of the range of tools which are available.
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| Tool |
Target Group |
Details |
| Range of simple self-reported questions |
All ages. Proxy respondents are often responsible for children. |
- There are a range of simple questions which can be used to identify individuals with impairments.
- These were often used on censuses and non-disability focused surveys, especially in earlier decades.
- They may ask for previous clinical diagnoses, or simply ask if the individual has an impairment and if so to classify the type of impairment.
- These questions may be used as a screening tool, to identify individuals to be followed up, or may be used as a standalone measure of prevalence and type of impairment.
|
| Clinical assessment |
All ages. May focus on particular types of impairment. |
- This involves each individual undergoing a full clinical examination by either a single clinician or a team of specialists.
- The type and number of specialists involved will depend on the focus of the study. For example, if looking at physical disability a physiotherapist may be required, whereas a study of visual impairment would require an ophthalmologist.
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| Tool |
Target Group |
Details |
| Rapid Assessment of Avoidable Blindness (RAAB) |
Population aged 50 and over |
- Aims to estimate the prevalence and causes of avoidable blindness.
- Involves visual acuity screening and examination of lenses.
- If visual acuity is lower than 6/18, an ophthalmologist will determine the cause.
|
| WHO Prevention of blindness (PBL) Eye Examination Record for Children with Blindness and Low Vision |
Population aged 15 and under |
- Not a tool, but a standardised form for recording visual impairment in children and etiological factors.
- Standardised format allows international comparability, as well as showing what data should be collected.
|
| WHO Ear and Hearing Survey Tool |
All ages |
- Standardised form for the recording of levels of hearing impairment and etiological factors.
- Standardised format allows international comparability, as well as showing what data should be collected.
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| Tool |
Target Group |
Details |
| Stanford-Binet Scale |
Population aged over 2 years |
- Designed to assess intelligence and cognitive ability
- Covers the domains of knowledge, quantitative reasoning, visual-spatial processing, working memory, and fluid reasoning.
|
| British Abilities Scale II (BAS II) |
Two separate scales for ages 2.6 – 7.0 years, and ages 7.0 to 17.2 years. |
- Consists of a series of individually administered tasks which assess skills such as reasoning, memory and visual recognition and is used to assess childhood development.
|
| Denver Developmental Screening Tool |
Children aged 0 – 6 years old |
- Widely used screening tool for identifying developmental delay in young children.
- The test consists of items in the domains of social/personal, fine motor function, language and gross motor function.
- Compares individual scores with age norms, and so local norms should always be assessed when using the tool in different contexts.
|
| Weschler Adult Intelligence Scale / Weschler Intelligence Scale for Children / Wechsler Preschool and Primary Scale of Intelligence |
Adults and older adolescents / Children aged 6-16 years / Children aged 3 – 7 years |
- Designed to assess cognitive ability.
- Can be used for assessing intellectual disabilities and cognitive function.
|
| Tool |
Target Group |
Details |
| Development and Well-Being Assessment (DAWBA) |
Children and adolescents aged 5-17 years |
- Interviews and questionnaires designed to generate psychiatric diagnoses
- Can be administered by humans or computer, with a significant reduction in costs when computer versions are used.
- Questions may be asked directly of the child, or of the parent, carer or teacher.
|
| WHO Composite International Diagnostic Interview (CIDI) |
Adults aged 18 and over |
- Fully structured interview for the assessment of mental disorders for epidemiological studies
- Designed to be used by lay interviewers
- Designed to be cross-cultural
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