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Assessment & diagnosis

ADOS-2, ADI-R and screening: diagnostic tools explained

Who is it for? For parents, people on the autism spectrum and interested readers who want to understand which instruments are used in assessment and what they do.

In brief

An autism assessment does not rest on a single test. There are no specific biomarkers; assessment is based on observable behaviour, on information from caregivers (among other things on early development) and on the interpretation of test results. [1] The internationally recognised standard is the combination of the Autism Diagnostic Interview (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS-2). [1] These methods too are not unreservedly specific: people with other mental disorders can have conspicuous scores. [1] The guideline on diagnosis (text version 2016) has expired and is being revised. [2; 3]

This English translation was produced with AI assistance and has not yet been independently reviewed.

Building blocks of assessment

According to the expert overview, an assessment includes, among other things [1]:

  • reports from nursery, school or earlier treatment (third-party history),
  • screening instruments as an indication for further assessment,
  • clinical observation of play, communication and interaction in different situations,
  • a physical and neurological examination that can rule out or identify possible organic causes or co-occurring conditions (for example genetic syndromes, epilepsy, hearing loss or visual impairment),
  • the standardised autism-specific examinations (ADI-R and ADOS-2),
  • clarification of co-occurring conditions and differential diagnoses.

What the process looks like overall: How an autism assessment works.

ADI-R: the interview with caregivers

The ADI-R is a structured parent interview with 93 items. It collects case-history information on early childhood development, language acquisition, current social-communicative abilities and special interests and activities. The caregivers give many concrete examples of behaviour from everyday life so that the interviewer can judge whether the examples indicate features in the sense of autism. [1]

ADOS-2: the behavioural observation

The ADOS-2 is a structured observation schedule that records communication, interaction and play behaviour in a standardised situation. It consists of five modules, chosen according to age and language level. The modules contain activities that deliberately create situations in which autism-specific features can occur. Depending on the module, the observation comprises 29 to 42 items, which are coded directly after the examination using a template. Administering it requires specific training, agreement between different raters (inter-rater) and broad experience with autism and with differential diagnoses. [1]

According to the expert overview, both methods are based on the diagnostic criteria of ICD-10 and DSM-4-TR/DSM-5. Scoring is done via a diagnostic algorithm that combines a selection of items. [1]

Screening questionnaires

Screening instruments serve the quick and simple detection of people at increased risk of autism. They are not suitable for making a diagnosis but an indication for further assessment. Their specificity in the clinical context is low, and their benefit is therefore limited. [1] An example in German-speaking countries is the Social Communication Questionnaire (FSK): it was developed for children and adolescents aged 4 to 18 years, comprises 40 yes/no questions (about 10 minutes) and is completed by parents or caregivers. [1] What this means for online tests: the result of a questionnaire does not replace an assessment.

Limits of the methods

  • No biomarkers. Assessment is based on behaviour, reports and the interpretation of test results. [1]
  • Limited specificity. People with other mental disorders that are associated with “autism like traits” can also have conspicuous scores on the ADI-R and ADOS-2. [1]
  • Diversity. Autism shows considerable heterogeneity (severity, language and cognitive abilities, co-occurring conditions) and overlaps with many other conditions. [1] Assessment therefore requires high professional competence and experience.

What else you should know

  • The methods are tools, not verdicts. What matters is the overall judgement by experienced professionals.
  • Preparation: Note down concrete examples from everyday life and collect reports from nursery, school or earlier treatment. This is a practical tip from the editorial team; the expert overview names third-party reports as a building block. [1]
  • Co-occurring conditions are also clarified: Common co-occurring conditions.
  • Adults: Autism assessment in adults.

Status of the guideline: The approach described follows the account in an expert overview from 2024, which according to its own statement is based on the S3 guideline on diagnosis. [1] The guideline (text version 23.02.2016) has expired: the overview of the lead professional society DGKJP gives its validity as “until 04.04.2021” [3], and the document itself carries a note that it has not been updated for more than five years and is currently being revised. [2] We will update this article as soon as a new version is available.

Note: This article offers general information. It does not replace a personal assessment, advice or treatment by professionals.

Sources and literature

  1. Höhne E, Kamp-Becker I. Diagnostik der Autismus-Spektrum-Störung. Pädiatrie (Rosenfluh) 2024;(4+5):27–32. https://rosenfluh.ch/media/paediatrie/2024/04-05/Diagnostik-der-Autismus-Spektrum-Stoerung.pdf – Expert overview (in German)
  2. DGKJP/DGPPN et al. Autismus-Spektrum-Störungen im Kindes-, Jugend- und Erwachsenenalter, Teil 1: Diagnostik. S3-Leitlinie, AWMF-Reg.-Nr. 028-018, Stand Text 23.02.2016. – Guideline (in German); expired, under revision
  3. DGKJP. Aktuelle Leitlinien (Eintrag 028-018: „Gültig bis 04.04.2021“). https://www.dgkjp.de/wissen/aktuelle-leitlinien/ – Professional society (website in German)

Terms from this article

ADOS-2
Autism Diagnostic Observation Schedule: a standardised observation procedure which, together with the ADI-R, is regarded as the international standard of autism assessment. Not a single 'test' for the diagnosis.
ADI-R
Autism Diagnostic Interview: a standardised interview with caregivers which, together with the ADOS-2, is regarded as the international standard of autism assessment.
Screening
A quick, simple procedure that points to an increased risk of autism. A screening is not suitable for a diagnosis, but is an indication for further clarification.
CARS
A behaviour observation scale used to assess features of autism. According to the 2016 guideline it is the oldest instrument of its kind and can be used from about the age of two.

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