Development and Initial Utility of the Autism Clinical Interview for Adults: A New Adult Autism Diagnostic Measure.

Background: Clinicians use diagnostic interviews to help them gather and organize information collected in the assessment of autism. Most instruments are developed for children and few measures have been developed that are reliable, valid, and appropriate for use in adulthood. This is a significant barrier to providing a high-quality, timely service for adults. The aim of this development study was to assess the initial utility of the recently developed Autism Clinical Interview for Adults (ACIA) for use in autism diagnostic clinical services before further large-scale testing and evaluation.

Methods: We invited adults who had received an autism spectrum diagnosis through a U.K. National Health Service (NHS) multidisciplinary adult autism assessment to participate. Seventeen autistic adults (8 women and 9 men, mean age of 37 years) and four relatives agreed to an interview. The semistructured ACIA interview comprises subject and informant versions, and a self-report preinterview questionnaire. In combination, the ACIA components cover topics relevant to autism and co-occurring condition assessment. We evaluated clinical utility and content validity via comparison with the Diagnostic and Statistical Manual Fifth Edition (DSM-5) and NHS diagnostic reports.

Results: Each interview took between 60 and 90 minutes to complete. Comparison with DSM-5 and the NHS autism diagnostic report demonstrated that the ACIA accurately identified information on core autism characteristics needed for a diagnosis, and identified co-occurring conditions. In response to participant suggestions we revised the interview.

Conclusions: These initial findings support the potential utility and validity of the ACIA for adult autism diagnostic clinical services. Further investigations of the acceptability, utility, and validity of this interview are planned.

Lay Summary: Clinicians use diagnostic interviews during assessments to help gather and record information both from a person suspected to be on the autism spectrum and from an informant (someone who knows them well). However, most autism diagnostic interviews were originally developed for assessing autism in childhood, and few have been developed for use with adults. The lack of diagnostic interviews developed specifically for use with adults makes it difficult to provide a good-quality, consistent assessment. The study tested a new semistructured diagnostic interview called the Autism Clinical Interview for Adults (ACIA). The ACIA includes a questionnaire for people to complete before their interview. This is followed by an interview that can be conducted with the person themselves and a separate version to be used with someone who knows them well (if permitted). The interview covers autism traits, strengths and difficulties, and co-occurring physical and mental health conditions. We wanted to find out if the interview is useful for autism diagnostic services by comparing information collected using the ACIA with clinical diagnostic reports. We invited people who had received a diagnosis of autism from a U.K. National Health Service (NHS) assessment to take part in an interview. We asked them if we could also interview someone who knew them well, and if we could compare their NHS autism diagnostic report with information gathered using the ACIA. Seventeen autistic adults (average age 37 years; 8 women and 9 men) and 4 relatives/supporters (2 parents, a spouse, and a cohabiting partner) agreed to be interviewed. Each interview took 60 to 90 minutes to complete. A comparison with clinical reports showed the ACIA identified autism traits relevant for a diagnosis, as well as co-occurring conditions (e.g., depression). Participants suggested some ways to improve the interview, and revisions were made. There are few diagnostic interviews designed specifically for use with adults seeking a diagnosis of autism. The findings from this study show that the ACIA is a promising new interview. The study is small. However, it is important to run an initial test study before involving more people and resources in larger studies. Building on these results, we aim to undertake further studies on the acceptability and usefulness of the new interview with a larger number of people, including people from a range of backgrounds. The ACIA has potential for use in adult autism clinical assessment services and as a resource for research and training. The semistructured format helps gather important and relevant information, and the interview length supports feasibility in clinical and research settings. The ACIA has the potential to streamline autism assessments and speed up the process for adults who currently wait a long time for their diagnosis.