Autism Diagnostic Observation Schedule

Method

The ADOS consists of a series of structured and semi-structured tasks that generally takes 30-60 minutes to administer. During this time, the examiner provides a series of opportunities for the subject to show social and communication behaviors relevant to the diagnosis of autism. Each subject is administered activities from the module that corresponds to their developmental and language level. The ADOS should not be used for formal diagnosis with individuals who are blind, deaf, or otherwise seriously impaired by sensory or motor disorders, such as cerebral palsy or muscular dystrophy.

Following task administration and observation coding, a scoring algorithm classifies the individual with autism, autism spectrum disorder, or non-spectrum. The toddler module algorithm yields a "range of concern" rather than a definite classification.

Modules

Toddler module

The toddler module is appropriate for children 12–30 months who use little to no phrase speech and are able to walk independently. This module consists of eleven primary activities:

1. Free play
2. Blocking toy play
3. Response to name
4. Bubble play
5. Anticipation of a routine with objects
6. Response to joint attention
7. Responsive social smile
8. Anticipation of social routine
9. Functional and symbolic imitation
10. Bath time
11. Snack

Module 1

Module 1 is appropriate for children 31 months and older who use little or no phrase speech. This module consists of ten activities:

1. Free play
2. Response to name
3. Response to joint attention
4. Bubble play
5. Anticipation of a routine with objects
6. Responsive social smile
7. Anticipation of a social routine
8. Functional and symbolic imitation
9. Birthday party
10. Snack

Module 2

Module 2 is appropriate for children six years old or younger who speak in phrases but have not yet developed fluent verbal language. This module consists of fourteen activities:

1. Construction task
2. Response to name
3. Make-believe play
4. Joint interactive play
5. Conversation
6. Response to joint attention
7. Demonstration task
8. Description of a picture
9. Telling a story from a book
10. Free play
11. Birthday party
12. Snack
13. Anticipation of a routine with objects
14. Bubble play

Module 3

Module 3 is appropriate for children or young adolescents who are verbally fluent. This module consists of fourteen activities:

1. Construction task
2. Make-believe play
3. Joint interactive play
4. Demonstration task
5. Description of a picture
6. Telling a story from a book
7. Cartoons
8. Conversation and reporting
9. Emotions
10. Social difficulties and annoyance
11. Break
12. Friends, relationships, and marriage
13. Loneliness
14. Creating a story

Module 4

Module 4 is appropriate for older adolescents and adults. While similar to module 3, module 4 relies more heavily on questions and verbal responses rather than non-verbal actions observed during play. This module consists of ten to fifteen activities. Activities marked by an asterisk are optional:

1. Construction task*
2. Telling a story from a book
3. Description of picture*
4. Conversation and reporting
5. Current work or school*
6. Social difficulties and annoyance
7. Emotions
8. Demonstration task
9. Cartoons*
10. Break
11. Daily living*
12. Friends, relationships, and marriage
13. Loneliness
14. Plans and hopes
15. Creating a story

Diagnostic accuracy

The social communication difficulties that the ADOS and ADOS-2 seek to measure are not unique to ASD; there is a heightened risk of false positives in individuals with other psychological disorders. In particular, an increased false positive rate has been observed in adults with psychosis; while case reports indicate that such false positives may also occur in cases of childhood-onset schizophrenia, which is an exceptionally rare entity with a frequency of 1 in 40000. There is evidence that adults with schizophrenia demonstrate an increased incidence of autistic features compared to the general population, resulting in higher ADOS scores, though schizophrenia patients also experience positive symptoms of psychosis (e.g. hallucinations, delusions, formal thought disorders).

A 2016 study found that 21% of children with a diagnosis of ADHD (and without a concurrent diagnosis of ASD) scored in the autism spectrum range on the ADOS total score.

The combined data indicate that the lifetime prevalence of ADHD among individuals with ASD is approximately 40%.

False positives have also been found in school-age subjects who have high anxiety or trauma-related disorders; in these cases, the ADOS-2 scores related to repetitive and restrictive behaviors (RRB) are usually lower than typical for ASD.

A 2018 Cochrane systematic review included 12 studies of ADOS diagnostic accuracy in pre-school children (Modules 1 and 2). The summary sensitivity was 0.94 (95% CI 0.89 to 0.97), with sensitivity in individual studies ranging from 0.76 to 0.98. The summary specificity was 0.80 (95% CI 0.68 to 0.88), with specificity in individual studies ranging from 0.20 to 1.00. The studies were evaluated for bias using the QUADAS-2 framework; of the 12 included studies, 8 were evaluated as having a high risk of bias, while for the remaining four there was insufficient information available for the risk of bias to be properly evaluated. The authors could not identify any studies for the ADOS-2; the scope of the review was limited to preschool age children (mean age under 6 years), which excluded studies of Modules 3 and 4 from the meta-analysis. One included study examined the additive sensitivity and specificity of the ADOS used in combination with the ADI-R; that study found an 11% improvement in specificity (compared to ADOS alone) at the cost of a 14% reduction in sensitivity; however, due to overlapping confidence intervals, that result could not be considered statistically significant.