"The single most important thing that has happened to me in my life" : development of the Impact of Diagnosis Scale-Preliminary Revision

Background: Awareness and diagnosis of autism in adulthood is on the rise. Studies have considered the impact of receiving an autism diagnosis for parents of children on the spectrum, although only few primarily qualitative studies have considered the self-reported impact of autism diagnosis. The Impact of Diagnosis Scale (IODS) was initially developed with a focus on borderline personality disorder. Our aim was to develop a version suitable for autistic individuals. Methods: The research team and a group of autistic advisors revised the IODS items for suitability and accessibility to autistic participants. We gathered participant data for 92 autistic adolescents and adults from the Cooperative Research Centre for Living with Autism (Autism CRC) Study of Australian School Leavers with Autism (SASLA) and the Australian Longitudinal Study of Autism in Adulthood (ALSAA). We used iterated principal factors analysis to explore potential factors, and thematic analysis to explore responses to two open-ended items. Results: Factor analysis suggested three factors of ''Service Access (SA),'' ''Being Understood (BU),'' and ''Self-Acceptance and Understanding (SU)'' for the 12 items of the IODS-Preliminary Revision (IODS-PR). Cronbach's alpha was good overall and acceptable for subdomains. Item mean scores suggest that although impact of autism diagnosis was generally perceived as positive for SU, scores were neutral in other domains. Qualitative analysis identified themes of Self-Understanding, Identity, and Acceptance, Supports and Services, Valence of Response, Relationships, and Camouflaging. Conclusions: The IODS-PR is the first scale to measure the self-reported experience of receiving an autism diagnosis. It showed good psychometrics and provides new insight into the experience of autism diagnosis. Qualitative analysis identified domains that remain unexplored and the potential for an expanded item set. A further revision of the tool will soon be available. It will provide critical information for clinicians and has potential applications for research and service evaluation.