The Swedish Versions of ADOS and ADI-R: Psychometric Validation

Objectives:

The present study seeks to determine for the first time the reliability and validity of the Swedish versions of the Autism Diagnostic Interview-Revised (ADI-R)and Autism Diagnostic Observation Schedule (ADOS). The combination of these two assessments is deemed the "gold standard" of diagnosing ASD in international practice and research. ADI-R and ADOS are widely used (translated into 15 languages) and have been rigorously and convincingly evaluated in other countries. The Swedish translations of the ADI-R (interview schedule, algorithms) and ADOS (observation schedules, algorithms) have not yet been tested for scientific properties and feasibility, hampering best clinical practice, evidence-based diagnostics and research premises for ASD in Sweden. Therefore, this study aims at standardizing the Swedish forms of the ADI-R and ADOS to and ensure their cross-cultural validity and clinical utility. A particular objective of the study is to establish the agreement of ADI-R and ADOS with register-based diagnoses. The latter is of paramount importance for judging the significance and generalizability of findings from large scale register research, which is a specific strength of Swedish science.

Instruments:

The ADI-R is a clinical diagnostic instrument for assessing ASDs in children, adolescents and adults. The ADI-R provides a diagnostic algorithm for autism as described in both the ICD-10 and DSM-IV-TR and necessary information for making a diagnosis of other ASD in accord with the classification manuals. The ADI-R is appropriate for children and adults with mental ages from about 18 months and above. It is a standardized, semi-structured clinical review for caregivers of children, adolescents and adults. The interview contains 93 items on three content areas: quality of social interaction, communication and language, and repetitive, restricted and stereotyped interests and behavior. The measure also includes other items relevant for treatment planning, such as self-injury and over-activity. Responses are scored by the clinician based on the caregiver's description of the child's behavior. All questions ask about current behavior, with the exception of a few behaviors that only occur during specific age periods. In addition to asking about current behavior, each question focuses on the time period when the behaviors were likely to be most pronounced - generally, between the ages of 4 and 5 years. The interview starts with an introductory question followed by questions about the subject's early development. The next 41 questions cover verbal and nonverbal communication. Questions 50 through 66 ask about social development and play. The next 13 questions deal with interests and behaviors. The final 14 questions ask about "general behavior," including questions about memory skills, motor skills, over-activity and fainting.

The ADI-R interview generates scores in each of the three content areas. Elevated scores indicate problematic behavior in a particular area. Scores are based on the clinician's judgment following the caregiver's report of the child's behavior and development. For each item, the clinician gives a score ranging from 0 (not autistic) to 3 (severely autistic). A classification of autism is given when scores in all three content areas of communication, social interaction, and patterns of behavior meet or exceed the specified cutoffs, and onset of the disorder is evident by 36 months of age. For other ASD information from the ADI-R is used informally: e.g. a diagnosis of Asperger syndrome is indicated, if the criteria for autism are fulfilled in face of normal language development, or a diagnosis of PDD-NOS, if social interaction deficits and another behavior domain exceed the cut-offs. This interviewer-based instrument requires substantial training in administration and scoring. A trained clinician can administer the ADI-R to the parent of a child suspected of autism in approximately 2 ½ hours.