APPENDIX B

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SUMMARY OF EVIDENCE
Summary Conclusions and Advantages and Limitations of Assessment Methods

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Clinical Clues for Possible Autism

Checklist for Autism in Toddlers (CHAT)

Autism Behavior Checklist (ABC)

Autism Diagnostic Interview - Revised (ADI-R)

Childhood Autism Rating Scale (CARS)

Pre-Linguistic Autism Diagnostic Observation Schedule (PL-ADOS)

Reviews of Other Evidence About Behavior Rating Scales for Autism

Reviews of Other Evidence about Structured Parent Interviews

 

ASSESSMENT METHODS

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Clinical Clues for Possible Autism in Young Children

Summary Conclusions

Several scientific studies have identified a number of specific behavioral deficiencies or abnormalities that can serve clinical clues for identifying children with possible autism. These clinical clues are behaviors (which parents, professionals or others dealing with a young child might identify) that heighten the concern for possible autism. The finding of a clinical clue for autism suggests that further appropriate assessment of the child is needed to determine if autism or some other condition is present.

The behavioral items listed in Table III-4 and summarized in Table III-5 are considered by the panel to be evidence-based clinical clues of possible autism in young children. The items on these tables that refer to limited social interaction and communication are clinical clues for a problem only if a typically developing child of the same age would be expected to display those behaviors (as shown Table III-3 : Normal Developmental Milestones for Communication and Social Skills).

The age ranges for subjects varied in the studies cited in Table III-5 , but all of these studies included some children under 6 years old. While the two studies evaluating only young children were given greater weight, the panel also considered the other three studies that evaluated broader age groups to provide useful information. This was considered reasonable in part because panel acknowledged that for most older children with autism, the specific behaviors associated with autism first appeared when they were young children (usually under 3 years old).

None of the behavioral items listed as clinical clues for autism (in Tables III-4 and III-5 ) was found to have both perfect sensitivity and specificity for identifying autism. This is not surprising since autism is defined as a spectrum of disorders that involve deficits in multiple developmental domains. For this reason not all the behaviors listed will be seen in every child who has autism and specific behavioral manifestations vary for different children with autism (implying less than perfect sensitivity). In addition, none of the clinical clues listed was found to be unique to children with autism, and each of the behaviors was seen in some children with other disorders who did not have autism (implying less than perfect specificity).

However, this less than perfect sensitivity and specificity does not diminish the value of these behavioral items as clinical clues, since the goal of clinical clues is to identify children with possible autism. In this sense, behaviors with a moderately high sensitivity would be useful to heighten the level of concern that a child may have autism (or some other developmental problem). While this information by itself would not be enough to establish if the child had autism, it would ideally lead professionals to carry out screening and possibly more in-depth assessment which would determine if the child had autism or some other developmental problem.

Summary Advantages and Limitations

Advantages

• Having parents and professionals look for clinical clues of possible autism in young children may be an important first step in identifying children with autism at an early age.
• Identifying clinical clues of possible autism may be an important first step that then triggers further screening and assessment.
• In determining if a deficiency in a specific behavior is a clinical clue for autism, it is necessary to know when these specific behaviors are first seen in typically developing children.
• Individual clinical clues for autism when viewed separately may provide an indication that further assessment is needed. However, when evaluated as a group (as part of a screening test, autism assessment instrument or set of diagnostic criteria), these behaviors provide much greater accuracy in identifying persons with autism.

Limitations

• No single clinical clue will perfectly identify children with autism.
• Relying on any particular abnormal or deficient behavior (or clinical clue) to identify persons with autism will result in both false positive and false negative results.

Checklist for Autism in Toddlers (CHAT)

Summary Conclusions

The Checklist for Autism in Toddlers is a brief screening instrument intended to detect possible autism in toddlers.

• Articles screened for this topic: 2
• Articles meeting criteria for evidence: 2

The CHAT was the only screening test designed to identify younger children with autism that has been evaluated in scientific studies that met criteria for adequate evidence about efficacy. The evidence reviewed suggests the CHAT is effective as a screening test to identify children with possible autism from 18 to 36 months.

Autism is relatively rare (approximately one to two per 1,000 children), so using the CHAT to screen all children in the general population for possible autism is not a practical approach. A more useful approach might be for professionals to use the CHAT with children in whom there is an identified parental concern or clinical clues suggesting possible autism. In these situations, the panel considered the potential benefits of using the CHAT outweighed any potential harms and costs of screening. There was no indication of any harms in using the CHAT.

If the CHAT suggests possible autism in a child, it is important to do a more in-depth assessment of possible autism, perhaps utilizing specific autism assessment instruments and/or referral to other professionals. Alternatively, if the CHAT suggests autism is unlikely, it is important that the child receive appropriate further developmental or health evaluation to address the originally identified concern.

The CHAT is primarily useful in helping to direct the further assessment of the child, rather than establishing a specific diagnosis. If there is a significant parent concern about autism, or a clinical clue suggesting possible autism, parents or healthcare professionals may decide that they have enough information and may not use the CHAT, but proceed to an in-depth developmental and/or health evaluation of the child.

Summary Advantages and Limitations

Advantages

• has been shown to be useful for children as young as 18 months.
• is easy and brief to administer and score.
• does not require special training and can be administered by a variety of professionals in various settings.
• has adequate sensitivity and specificity for detecting young children at risk for being diagnosed with autism.

Limitations

• is intended as a screening instrument and not a tool to make a formal diagnosis.
• there may be false positive and false negative results.
• may incorrectly identify autism in children with severe developmental delays who do not have autism.
• may miss some children whose early symptoms of autism are mild and/or non-specific, or whose symptoms have not yet emerged.

Autism Behavior Checklist (ABC)

Summary Conclusions

The Autism Behavior Checklist is a list of questions about a child's behaviors and is designed to be completed independently by a parent or a teacher familiar with the child.

• Articles screened for this topic: 13
• Articles meeting criteria for evidence: 3

Although the ABC does have the advantage of being an objective standardized method for assessing children with autism, its demonstrated sensitivity and specificity for identifying children with autism was relatively low (especially when compared to other autism assessment instruments). In addition, the content of the test items appears more appropriate for children over three years old. For these reasons, the panel considered the ABC to be of limited usefulness in identifying young children with autism, especially when compared with other autism assessment instruments.

Summary Advantages and Limitations

Advantages

• brings some degree of objectivity, standardization, and consistency to the clinical decision-making process.
• provides a structured format for gathering and recording information.
• is easy to use.
• can complete by a variety of individuals familiar with the child, including a parent or a teacher.
• can be mailed to parents to complete at home.

Limitations

• more than 15 years old, it does not fully reflect current information about cognitive and social development in young children with autism.
• questions are primarily directed to children over 3 years old.
• might fail to detect as many as 40% to 60% of children with autism.
• there may be a problem in using it as a measure of severity in the young child.
• provides no curriculum guidance; does not provide specific information about the child's strengths or weaknesses.

Autism Diagnostic Interview - Revised (ADI-R)

Summary Conclusions

The Autism Diagnostic Interview - Revised is a semi-structured interview for a clinician to use with the child's parent or principle caregiver.

• Articles screened for this topic: 12
• Articles meeting criteria for evidence: 2

The ADI and ADI-R are semi-structured parent interviews that touch on all the domains of autism as specified in the DSM-IV. The ADI-R is a relatively new and shorter version of the ADI. The ADI and the ADI-R are designed to be administered by professionals and require extensive training.

For younger children, the ADI-R is considered more appropriate than the ADI. Therefore, the guideline recommendations only address use of the ADI-R. Evidence on the efficacy of the ADI is considered important as supporting material regarding the usefulness of both of these tests.

A major advantage of the ADI-R is its tie to the most current diagnostic criteria (the DSM-IV). The ADI-R has demonstrated good sensitivity and specificity in validity testing in independent samples. Because the ADI-R requires extensive time and training to administer, it may be most useful as part of a more in-depth assessment of children for whom screening tests, clinical clues, or other factors suggest a fairly high level of concern for possible autism.

Summary Advantages and Limitations

Advantages

• brings some degree of objectivity, standardization, and consistency to the clinical decision-making process.
• provides a structured format to help ensure that all the important types of historical information are gathered, organized, and interpreted.
• interview helps some parents have a better understanding of the factors that are being evaluated in order to reach a diagnosis.
• is tied to DSM-IV diagnostic criteria and current knowledge about autism in young children.
• has a standardized scoring algorithm.
• is focused on children in the 3-5 year range and can be used with children as young as age two. It is designed for use with children with mental age down to 18 months.
• has adequate sensitivity and specificity when administered by highly trained individuals.

Limitations

• may be false positive and false negative test results.
• has not been studied in diagnosing autism in children under the age of three years.
• that professionals who wish to use the ADI-R receive extensive and expensive formal training administering and interpreting this test training is expensive.
• test administration requires a great deal of time for both professionals and parents. The interview itself may take one to two hours and the scoring will require additional time.

Childhood Autism Rating Scale (CARS)

Summary Conclusions

The Childhood Autism Rating Scale is the most widely used standardized instrument specifically designed to aid in the diagnosis of autism.

• Articles screened for this topic: 19
• Articles meeting criteria for evidence: 3

Among the autism assessment instruments reviewed, the CARS appears to possess an acceptable combination of practicality and research support, despite the limited research on its use in children under three years of age. The CARS may be useful as part of the assessment of children with possible autism in a variety of settings, such as early intervention programs, preschool developmental programs, and developmental diagnostic centers. Because it gives a symptom severity rating, the CARS may be useful for periodic monitoring of children with autism and for assessing long-term outcomes. It is very important that professionals using the CARS have experience in assessing children with autism and undergo adequate training in administering and interpreting the CARS.

The use of an autism assessment instrument that is practical, has some research support, and allows a severity rating (such as the CARS), would allow collection of consistent information on a statewide basis.

Information from the CARS could be useful for estimating the prevalence of children with autism and assessing functional outcomes (especially if tied to other information about interventions and service delivery).

Summary Advantages and Limitations

Advantages

• brings some degree of objectivity, standardization, and consistency to the clinical decision-making process.
• provides a structured format for gathering and recording information.
• useful for children as young as age two (although there are limited data validating its usefulness in this younger age group).
• has adequate sensitivity and specificity provides a measure of severity of the symptoms of autism when administered by highly trained individuals.
• training materials for administering and interpretation are readily available.

Limitations

• there may be false positive and false negative test results.
• may not identify some children with milder presentations of autism, such as those with PDD-NOS.
• may incorrectly identify autism in children with more severe mental retardation who do not have autism.
• the sensitivity and specificity have not been demonstrated when is not given by highly trained raters.
• may not fully reflect current information about cognitive and social development in young children.

Pre-Linguistic Autism Diagnostic Observation Schedule (PL-ADOS)

Summary Conclusions

The Pre-Linguistic Autism Diagnostic Observation Schedule version is a version of the Autism Diagnostic Observation Schedule (ADOS) modified to diagnose young children (under the age of six years) who are not yet using phrase speech. It is a semi-structured assessment of play, interaction, and social communication.

• Articles screened for this topic: 5
• Articles meeting criteria for evidence: 1

The PL-ADOS is an in-depth standardized assessment instrument that brings some degree of objectivity and consistency to the clinical decision-making process. An advantage of the PL-ADOS is that the algorithm for scoring this test is based on the most current diagnostic criteria (the DSM-IV). In research settings, the PL-ADOS has been demonstrated to have adequate sensitivity and specificity for identifying children with autism. Since extensive training is needed to learn how to administer the PL-ADOS, this may not be a practical assessment method in certain clinical situations. However, the PL-ADOS may be useful as part of a multidisciplinary intake assessment in diagnosing young children with possible autism.

Summary Advantages and Limitations

Advantages

• brings some degree of objectivity, standardization, and consistency to the clinical decision-making process.
• provides a structured format for gathering and recording information.
• is based on direct observation.
• has a standardized scoring algorithm based on the DSM-IV.
• useful for young pre-verbal children.
• has adequate sensitivity and specificity when administered by highly trained individuals.

Limitations

• there may be false positive and false negative test results.
• sensitivity and specificity have not been validated in an independent sample.
• has not been shown to be effective in diagnosing autism in either in children under age three or in verbal children.
• standardized set of toys is expensive.

Reviews of Other Evidence about Behavior Rating Scales for Autism

Summary Conclusions

The Behavioral Summarized Evaluation (BSE) is an assessment instrument that uses direct observations of the child to provide a score rating the severity of the autistic symptoms.

• Articles screened for this topic: 6
• Articles meeting criteria for evidence: 3

An autism assessment instrument that provides a symptom severity rating, such as the BSE, may be useful for periodic monitoring of children with autism and for assessing outcomes.

A behavior rating scale completed by someone familiar with the child (such as a parent, childcare professional or teacher) may provide information that is useful in helping to identify and diagnose children with autism. It is important that such tests be interpreted by a professional with expertise in assessing children with autism.

Summary Advantages and Limitations

Advantages:

• The IBSE and BSE provide a structured format for gathering and recording information.
• The IBSE is designed for use with younger children; it has been used with children under three years of age.
• The IBSE and BSE provide a measure of severity of the symptoms of autism.
• The IBSE and BSE can be used by a variety of individuals.
• When administered by trained individuals, the IBSE and BSE have adequate sensitivity and specificity (using DSM-III-R and expert clinical diagnosis as reference standards).

Limitations:

• As with all diagnostic tests, there may be false positive and false negative test results.
• Since the BSE was developed and studied in France, it is unclear what the sensitivity and specificity of the BSE would be in the United States.
• The BSE may not identify some children with mild symptoms of autism.

Reviews of Other Evidence about Structured Parent Interviews

Summary Conclusions

• Articles screened for this topic: 1
• Articles meeting criteria for evidence: 1

A structured parent interview (such as the Parent Interview for Autism (PIA) may be useful as part of the assessment of children with possible autism, especially if there is research evidence that the particular assessment instrument has adequate sensitivity and specificity for identifying children with autism. It is important to supplement the structured parent interview with direct observation of the child.

Summary Advantages and Limitations

Advantages:

• brings some degree of objectivity, standardization, and consistency to the clinical decision-making process.
• provides a structured format for gathering and recording information.
• can have an acceptable sensitivity for identifying children with autism .

Limitations:

• there may be false positive and false negative test results.
• sensitivity and specificity were not validated in an independent sample.
• is not designed as a substitute for direct observation of the child.

Send questions or comments to: bei@health.state.ny.us
Revised: November 1999