3.6.3.90 Guidelines to Table 9 - Intellectual Function

Summary

Table 9 is used to assess the functional impact from a condition resulting in low intellectual function (a meaningful intelligence quotient (IQ) score of 70 to 85). A meaningful IQ is one which best represents the person's general intellectual function. To use Table 9, this impairment in intellectual function must have originated before the person turned 18 years of age.

Conditions causing impairment commonly assessed using Table 9

There are a range of conditions a person may have which cause impairment affecting intellectual function that can be appropriately assessed using Table 9. These include intellectual impairment resulting from, but not limited to:

• Down syndrome
• congenital/perinatal or early childhood infections (for example, rubella, cytomegalovirus (CMV), bacterial meningitis, encephalitis)
• extreme prematurity or birth trauma
• a person with either autism spectrum disorder (ASD), fragile X syndrome or fetal alcohol spectrum disorder (FASD) who also has a meaningful IQ between 70 and 85 resulting in functional impairment
• childhood developmental or congenital disorders.

Diagnosis & evidence

The assessment of a person's condition must be made by an appropriately qualified psychologist who is able to administer an assessment of intellectual function and an assessment of adaptive behaviour.

An assessment of intellectual functioning and adaptive behaviour is to be undertaken in the form of an individually administered and psychometrically valid, comprehensive, culturally appropriate and psychometrically sound standardised assessment.

Examples of tools used to assess intellectual functioning include:

• the Wechsler Adult Intelligence Scale (WAIS-IV) or equivalent (which should be conducted after the person turns 16 years of age)
• the Wechsler Intelligence Scale for Children (WISC-V) (which should be completed between the ages of 12 and 16 years, but is also acceptable for people aged 18 years or under at the time of assessment).

Examples of tools used to assess adaptive functioning include:

• the Adaptive Behaviour Assessment System (ABAS-3)
• the Scales for Independent Behaviour – Revised (SIB-R)
• the Vineland Adaptive Behaviour Scales (Vineland 3).

As these measures are based on responses from carers, teachers or self-report, consideration should be given to the capacity of the person reporting on the adaptive behaviour, for example, insight, observations in various settings, social and cultural expectations.

Consideration should be given to the validity of the assessments of adaptive function and whether the results are consistent with other corroborating evidence such as developmental history, formal assessment, school or work records and/or direct observation. If the measure of adaptive function is inconsistent with this, clinical judgement should be used to determine the level of adaptive behaviour that is consistent with the scores of adaptive behaviour found in the Table 9 descriptors.

Consideration of the adaptation of recognised assessments of intellectual function for use with Aboriginal and Torres Strait Islander peoples is required.

Other assessments that could be considered, depending on the circumstances of the person being assessed include:

• Test of Nonverbal Intelligence (TONI-4)
• Ravens Progressive Matrices (RPM)
• Universal Nonverbal Intelligence Test (UNIT-2)
• Wechsler Nonverbal Scale of Ability (WNV)

For culturally and linguistically diverse (CALD) people, the TONI-4, or other equivalent tests of intelligence validated for CALD populations, may also be considered.

People with ASD or FASD who also have a meaningful IQ between 70 and 85 resulting in functional impairment must be assessed under Table 9.

However, in cases where the person with ASD does not have a meaningful IQ between 70 and 85 resulting in functional impairment, Table 7 – Brain Function should be considered. When another table is being considered in addition to Table 9, see below – ‘Avoiding double counting’.

For people with a meaningful IQ score of less than 70, the manifest eligibility criteria must be applied (3.6.2.20 and 3.6.2.50). The manifest eligibility criteria must also be applied for people whose intellectual impairment is so severe they are unable to undertake an IQ test.

The assessment of IQ can be complex, for example, if there are significant discrepancies in indices. In some instances, a variable cognitive profile may not make a full scale IQ score the most meaningful summary of a person's intellectual function. In some instances, the General Ability Index (GAI) or other suitable index score may be used, if appropriate. However, if these scores are not meaningful, it may be more appropriate to assess the person’s functional impairment under Table 7 – Brain Function.

Assistance may be required in interpreting test results that are reported in psychological, neuropsychological, or educational reports. In such instances, consultation with a Services Australia psychologist or a referral to the HPAU should be undertaken.

A PERSON'S SELF-REPORTED SYMPTOMS MUST NOT BE SOLELY RELIED UPON in determining the functional impacts of the person's condition (impairment). There must be corroborating evidence of the person's impairment.

Examples of corroborating evidence for the purposes of Table 9 include, but are not limited to:

• a report from the person’s treating doctor
• supporting letters, reports or assessments relating to the person’s development, intellectual function, adaptive behaviour or participation in programs (such as a paediatrician)
• interviews with the person and those providing care, support or treatment to the person.

Interpretation & application of relevant terms

Under Table 9, both an assessment of intellectual function and an assessment of adaptive behaviour must be undertaken.

An assessment of intellectual function is to be undertaken using an appropriate assessment tool that was current and valid at the time of testing intellectual function, such as the WAIS IV or equivalent contemporary assessment tool. This assessment should be conducted after a person turns 16 years of age. A Wechsler Intelligence Scale for Children assessment completed when the person was between the age of 12 years and the age of 16 years and 11 months is also acceptable for people aged 18 years or under at the time of assessment. If the assessment tool used is not appropriate or there are any concerns that existing scores do not reflect the person's current circumstances, re-testing should be considered following consultation with a Services Australia psychologist.

Depending on the cause of the intellectual impairment, the impaired functioning measured before a child turns 12 years of age may or may not remain constant into adulthood. Therefore, any additional evidence should be reviewed to determine if further assessment is required after the age of 12 years.

If a valid and current assessment of adaptive behaviour is not available, referral for specialist assessment may be necessary (3.6.2.15).

Other contemporary standardised assessments of adaptive behaviour may be undertaken as long as they:

• provide robust standardised scores across the 3 domains of adaptive behaviour (conceptual, social and practical adaptive skills)
• have current norms developed on a representative sample of the general population
• demonstrate test validity and reliability
• provide a percentile ranking
• are a measure of stable adaptive deficit, rather than a temporary reduction in adaptive behaviour, and
• are indicative of the person's adaptive behaviour due to their intellectual function at the time of DSP assessment.

Determining the level of functional impact - rules

When establishing whether a person’s impairment causes no or minimal (0 points), mild (5 points), moderate (10 points), severe (20 points) or extreme (30 points) functional impact, each descriptor and all its paragraphs for an impairment rating level in the Table must be read as a whole.

The structure of the Tables requires that, in assessing the level of functional impact, a comparison must be made of all the descriptors for each level of impairment. This does not necessarily mean all descriptors must be met, but all must be considered to determine which descriptors apply to the person’s impairment.

Table 9 is scaled against a person’s adaptive behaviour score or a standardised assessment of adaptive behaviour rank.

The descriptors in Table 9 outline how a score of adaptive behaviour aligns with an impairment rating. For example, to meet the 20-point descriptor, a person must have either a score of adaptive behaviour between 51 and 70 or be assessed within the percentile rank of 0.1 to 2.

The assessment is solely based on the person’s score of adaptive behaviour or percentile ranking.

Determination of the descriptor that best fits a person's impairment level must be based on the available medical evidence, of their score of adaptive behaviour or percentile ranking. A person's self-reported adaptive functioning must not solely be relied on. An impairment rating must not be applied unless the person's self-reported functional impacts are consistent with and supported by the medical evidence available.

Professional judgement is required regarding the best source of intellectual function and adaptive functioning information as in some instances it will be appropriate to obtain input from a parent, caregiver or teacher. A person's IQ and adaptive functioning test results must not be considered in isolation as they may also have insufficient insight into their condition.

The following table describes how adaptive behaviour tools align with impairment ratings under Table 9.

Impairment Ratings for Table 9

0-point impairment rating level

The 0-point descriptor requires that the person have NO OR MINIMAL impact on adaptive functioning.

For this rating to be assigned, at least one of the descriptors (1)(a), or (1)(b) must apply.

5-point impairment rating level

The 5-point descriptor requires that there is MILD functional impact on adaptive functioning.

For this rating to be assigned, at least one of the descriptors (1)(a), or (1)(b) must apply.

10-point impairment rating level

The 10-point descriptor requires that the person have MODERATE impact on adaptive functioning.

For this rating to be assigned, at least one of the descriptors (1)(a), or (1)(b) must apply.

20-point impairment rating level

The 20-point descriptor requires that the person have SEVERE impact on adaptive functioning.

For this rating to be assigned, at least one of the descriptors (1)(a), or (1)(b) must apply.

30-point impairment rating level

The 30-point descriptor requires that the person have EXTREME impact on adaptive functioning.

For this rating to be assigned, at least one of the descriptors (1)(a), or (1)(b) must apply.

Avoiding double counting

Double counting of impairments must be avoided (see 3.6.3.06 ‘Rating multiple conditions with common impairments & double counting’).

In cases where the person with ASD does not have a meaningful IQ between 70 and 85 resulting in functional impairment, Table 7 – Brain Function or Table 5 – Mental Health Function should be considered.

Where a person’s impairment affecting communication function is due to impairment in intellectual function, only Table 9 must be used. An additional rating on Table 8 – Communication Function should not be applied

Examples of Table 9 assessment

Impairments that should not be assessed using Table 9

Behavioural problems unrelated to intellectual impairment may be assessed using Table 5 - Mental Health Function, if there is a permanent mental health condition.

For people with ASD or FASD who do not have a meaningful IQ between 70 and 85 resulting in function impairment, Table 7 – Brain Function may be applied.