Psychometric Properties of the Dimensional, Diagnostic and Dimensional Interview Version for Adults (3DIVA)

Background:  

A substantial number of cases of autism spectrum conditions (ASC) (also know as 'autism spectrum disorder', or 'autism') go undetected in childhood, and people do not grow out of ASC as they become adults. Therefore a number of individuals with autism progress to adulthood without receiving a diagnosis, in particular those with subtle symptoms, occurring in the context of a normal-range IQ and fluent language. As a result there is increasing acknowledgement amongst policy makers and healthcare professionals of the need to develop valid means of assessing autism in adults, to inform targeted support and intervention.

A cornerstone of autism assessment is informant report, preferably from someone (such as a parent) who knew the assesse in childhood. A valid assessment requires that such informant reports be integrated with self-report and direct observational information. Currently there are no validated, standardised informant-report measures designed for assessing adult autism, as defined in DSM-5.

The Dimensional, Diagnostic and Dimensional Interview version for adults (3DIVA) comprises 71 questions, 24 of which are historical, covering the assessee’s life between birth and adolescence. Its algorithm outputs scores for the two DSM-5 domains of ‘social communication and social interaction’ and ‘restricted repetitive patterns of behaviour, interests or activities’. The 3DIVA is intended for use with adults who have an IQ above 70, reflecting the increased risk of such individuals being missed in childhood and so presenting to adult services for assessment.  It is a highly structured interview, and so is suitable for administration both in person and by telephone, as in the assessment of adults, parental report can sometimes be attained over the telephone but not face-to-face. 

Objectives: To measure the reliability and validity of the 3DIVA, including its ability to discriminate autism from mental disorders such as anxiety, psychosis and depression.

Methods: Participants (N=86) were: (1) adults with autism (n=39); (2) adults without autism who were receiving clinical intervention for a mental health problem (‘clinical comparison group’) (n=20); and (3) adults without autism from the general population (‘non-clinical comparison group’) (n=27). The groups did not differ on IQ, number of years in education, or age. In the majority (85%) of cases the informant completing the 3DIVA was the index participant’s mother.

Results: The 3DIVA showed excellent reliability (Cronbach’s alpha’s >.93, inter-rater reliabilities >.98). Criterion validity was shown by the strong sensitivity and specificity of the instrument, which correctly identified 93% of those with autism (sensitivity), and 92% of the non-autism participants (specificity). Evidence for construct validity was shown by the lack of association between 3DIVA DSM-5 algorithm scores and age or IQ.

Conclusions: The 3DIVA shows promise as a quick (< 40 minutes), reliable and valid informant-report tool for assessing whether an adult has high-functioning autism. It was able to discriminate between autism and conditions such as anxiety, psychosis and depression, and so could be used in general adult mental health settings, as well as in specialist neurodevelopmental services.