### Disability among children: a statistical perspective

**How are children defined?**

In carrying out national surveys of children, three characteristics need
to be clearly defined in terms of who to include in and who to exclude
from the study -- age range, kinship, and usual place of residence.

Making meaningful comparisons among surveys or censuses that produce
disability data about children are made more difficult by the different
age ranges covered and how single ages are aggregated into aged bands.
The key question is what should be the minimum and maximum age of the
target population. In some cases data are collected from birth; in other
instances data are only available from children aged five and above. The
maximum age is normally fifteen or sixteen.

The relationship between the child and the adults in the household is
another important factor for data comparability. Biological children,
step children and foster children are often treated in different ways in
different surveys.

For survey purposes, it is also important that children are not double
counted. Some children will live with one parent for a part of the week
and the other parent for the remainder of the time. Therefore, it is
necessary to establish the child's main residence. In some countries,
children may board at schools during term time and only return home
during vacations.

**How is disability defined in relation to children.**

It is generally assumed that the same question on disability is
applicable to adults of all ages (though there is some evidence that
they work less well with the elderly population). This is certainly not
the case with children. Bone and Meltzer (1989) in their discussion of
the national survey of disability among children in Great Britain,
stated that for children, the notion of what is normal for a particular
age is an inescapable basis for assessment of disability; very young
children in particular can not do what adults can, and consequently
questions designed to identify the presence and severity of disability
among adults are inappropriate for them. Questions on disability
addressed to adults may be inappropriate in a different way to older
children. Some older children may be able to perform some of the tasks
asked of adults such as washing or cooking but in some cultures they are
not expected to do so, and their ability in those respects may be
unknown. There are also activities like running which children but not
adults need to perform to lead a normal daily life among their peer
group. Finally, behavioural problems among children are predominantly of
a different kind from those of adults as a whole.

However, there are different ways of measuring developmental delay and
these affect prevalence estimates. In order to measure the prevalence of
developmental delay among US infants and children Simps, Colpe and
Greenspan (2003) asked two types of questions of parents in the 1994-95
National Health Interview Survey on Disability. To measure functional
delay, questions from the Functional Developmental Growth Chart, which
measures specific age-appropriate tasks, were used. General delay was
defined using the general type of questions about developmental delay
that had been used in previous surveys. Using a nationally
representative sample of 15 291 infants and children aged 4-59 months
from the NHIS-D, they found that approximately 3.3% had functional delay
and 3.4% of the children had general delay. However, only one-third of
the children were identified by both sets of questions. Thus, two-thirds
of the children identified as having a functional delay were not
recognised by their parents as having a delay. Conversely, many parents
responded to the general delay questions indicating that their child had
a delay, but failed to indicate that their child had a functional
problem. They concluded that the general types of developmental delay
questions used in national surveys may not identify children with
functional delays.

Westbrook, Silver and Stein (1998) also compared different ways of
measuring disability among children. They looked at the extent to which
prevalence estimates and characteristics of children varied by the way
that disability is defined. Specifically, they calculated the
proportions of children identified as disabled by one particular
operationalization of disability based on parental reports of three
types of consequences: functional limitations, dependence on
compensatory mechanisms, and service use or need beyond routine. They
also determined whether children identified as disabled by these three
types of consequences differ by type of disorder or condition, age,
socioeconomic status, or race. They analysed a national dataset
representing a random sample of 712 households with 1388 children. The
Questionnaire for Identifying Children with Chronic Conditions (QuICCC)
was used to identify children with disabling conditions. The QuICCC
items were divided into three discrete sets, reflecting the three
definitional components of disability, and compared the proportions and
characteristics of children fitting these components separately and in
combination.

Using the QuICCC definition of disability, the use of specialised
services identified the largest proportion of children (72%), followed
by dependence on compensatory mechanisms (55%) and functional limitation
(49%). Forty-four percent of children were identified by only one
component, 36% by two components in any combination, and 20% by all
three components. The type of disorder or condition generally did not
vary by the three definitional components, although the functional
limitation component appeared be more effective at identifying children
with sensory impairments. Children identified by two or more components
were more likely to have multiple conditions and had more pervasive
disorders than those identified by only one component. The youngest
children (0 to 3 years old) may be less likely to be identified as
disabled than children of other ages, especially by functional
limitations.

They concluded that although the specific findings pertain to a single
definitional approach (the QuICCC), the data highlight that who will be
classified as disabled (and who will not) may be dependent on how
disability is defined. The implications of using different definitions
and definitional components on both the prevalence and the
characteristics of children with disabilities need to be considered
before data can be applied responsibly and appropriately.\
\
Another key difference between surveys of the prevalence of disability
among adults and children is that in some countries there is a more of a
focus on impairments than functional difficulties in the children'
surveys (Cans, Baillie and Jouk, 1994; Li, 1991) probably as a result of
the complexity in operationalising developmental delay.

McDougall and Miller (2003) reviewed the coverage of chronic health
conditions and the domains of disability and related environmental
factors as they are laid out in the ICD-10 and ICF, respectively, in
national surveys of school-aged children conducted in Canada since 1980.
Coverage of chronic health conditions, the domains of disability, and
environmental factors in survey questions was identified by mapping
question content onto ICD-10 and ICF codes. They found that surveys
under review varied in the range and depth of coverage of the ICD-10 and
ICF chapters. Disability surveys and health surveys for persons aged 12
and over contained the most comprehensive lists of chronic conditions.
Coverage of impairments was limited. Coverage of activity limitations
and participation restrictions was most limited in the domains of
personal care and domestic life.

Wells and Hogan (2003) have commented that although several national
health surveys have implemented data collection efforts to identify and
characterise disability among children, the large number of items these
surveys have required to measure childhood disability prohibit their use
in general population surveys.

# What is the purpose of collecting disability data for children? Is it the same as for adults?

In the discussion of the rationale behind collecting disability data on
adults, three main purposes have been considered: equalisation of
opportunity, monitoring service utilisation and measuring the health of
the population.

Equalisation of opportunity is just as important for disabled children
as for disabled adults. However, education takes the place of employment
as the main focus for policies on equalisation of opportunity. There has
been an on-going debate on whether disabled children should receive
their education via mainstream schooling or within separate, specialised
settings.

In many counties services for children are not so well developed as
those for adults therefore, surveys which examine unmet need are of
particular relevance for children.

It is also important to monitor the health of young people aged 15 or
16. It is at this time of transition from secondary to tertiary
education or into employment that particular problems may arise for
disabled children. There is often a lack of co-ordination of service
provision for children during the transition to adulthood.

# How are children dealt with in censuses and health interview surveys?

There seem to be different procedures in how children are dealt with in
censuses and surveys. Various practices include:

-   Censuses which include all children (from birth)

-   Censuses which include children from a certain age.

-   Surveys which ask questions about all household members including
    children

-   Surveys which ask questions about all household members including
    children from a certain age.

-   Separate surveys of children.

Undoubtedly, the decision on which procedure is used depends on the
country's statistical infrastructure, the resources available for data
collection and the political will to make data collection on children a
priority.

# How are children sampled for general population surveys?

One of the main challenges in carrying our surveys of children,
regardless of topic, is obtaining a representative sample of the child
population. Various methods have been tried, each have their advantages
and disadvantages.

Sampling through school records is certainly one of the cheaper options
but the hurdles that need to be overcome are: getting a representative
sample of schools to co-operate, getting schools to allow access to data
which may be covered by data protection acts or confidentiality
agreements, getting to the parent to give consent via the child.
Children with severe physical health problems may not be at school and
those with behavioural problems may be excluded from school.

Another way of obtaining a sample of children is to carry out a postal
sift of the population trying to identify households with children. This
method is very expensive as one may need to send out ten times the
number of letters in relation to the number of children who eventually
become subjects of the survey.

Another method commonly used is to try and sample from centralised,
computerised, administrative records. These may relate to health or
universal benefits. Similar to the situation of sampling children via
schools, confidentiality and data protection issues need to be
addressed.

A fourth method is to "piggy-back" on another survey. This can entail
obtaining disability data on children in households which have been
selected for the adult health interview survey or using households which
contain children sampled for various other purposes. In this case, the
biggest problem is respondent burden.

What are the ethical issues in surveying children?

*Participation of children*

Wherever possible, children should be invited to participate in the
survey process. Especially when dealing with mental health or sensitive
issues, parents or carers may not be aware of all the child's problems.
Some studies have involved children as young as eight while others wait
until the child is eleven. However, it should be recognised that not all
11 year olds have the same intellectual capacity and simple language is
essential if the child is answering questions posed by an interviewer,
or filling in a self-completion questionnaire on paper or via a lap-top
computer.

## Parent/carer interview

Whether or not the child is old enough or capable of answering
questions, questions about the child's health or disability will be put
to the child's parent or carer first. Wherever possible the parent
should answer the questions out of earshot of the child in the study.
Most survey organisations have rules of confidentiality ensuring that
what is said by the parent (or the child) is not passed on to anyone
else including teachers.

## Child is severely disabled

## 

## There is a possibility that some of children sampled in the survey may be so physically or mental disabled (e.g., no movement, no speech, no sight and hearing) that the questions may seem inappropriate or indelicate. Therefore, introductions to sections of questions need to be carefully crafted to avoid parental distress or discomfort. 

## 

## Cases of abuse

In a child health survey, there is a possibility, however unlikely that
a child may report on-going abuse. There is a greater likelihood that
the child might talk about abuse in the past. Another scenario may be a
child reporting suicidal thoughts. Procedures need to be put in place to
deal with these issues.

# Any empirical evidence, lessons learnt

Despite all the methodological, ethical and logistical problems in
conducting surveys among children quite a body of material has bee
published reflecting the importance all over the world of the need to
obtain data on disabled children.

#  

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