Development and validation of the suicidal behaviours questionnaire - autism spectrum conditions in a community sample of autistic, possibly autistic and non-autistic adults

BACKGROUND: Autistic people and those with high autistic traits are at high risk of experiencing suicidality. Yet, there are no suicidality assessment tools developed or validated for these groups. METHODS: A widely used and validated suicidality assessment tool developed for the general population (SBQ-R), was adapted using feedback from autistic adults, to create the Suicidal Behaviours Questionnaire—Autism Spectrum Conditions (SBQ-ASC). The adapted tool was refined through nine interviews, and an online survey with 251 autistic adults, to establish clarity and relevance of the items. Subsequently, 308 autistic, 113 possibly autistic, and 268 non-autistic adults completed the adapted tool online, alongside self-report measures of autistic traits (AQ), camouflaging autistic traits (CAT-Q), depression (PHQ-9), anxiety (ASA-A), thwarted belongingness and perceived burdensomeness (INQ-15), lifetime non-suicidal self-injury, and the original version of the suicidality assessment tool (SBQ-R). Analyses explored the appropriateness and measurement properties of the adapted tool between the groups. RESULTS: There was evidence in support of content validity, structural validity, internal consistency, convergent and divergent validity, test–retest validity, sensitivity and specificity (for distinguishing those with or without lifetime experience of suicide attempt), and hypothesis testing of the adapted tool (SBQ-ASC) in each group. The structure of the SBQ-ASC was equivalent between autistic and possibly autistic adults, regardless of gender, or use of visual aids to help quantify abstract rating scales. LIMITATIONS: The samples involved in the development and validation of the adapted tool were largely female, and largely diagnosed as autistic in adulthood, which limits the generalisability of results to the wider autistic population. The SBQ-ASC has been developed for use in research and is not recommended to assess risk of future suicide attempts and/or self-harm. The SBQ-ASC has been designed with and for autistic and possibly autistic adults, and is not appropriate to compare to non-autistic adults given measurement differences between these groups. CONCLUSIONS: The SBQ-ASC is a brief self-report suicidality assessment tool, developed and validated with and for autistic adults, without co-occurring intellectual disability. The SBQ-ASC is appropriate for use in research to identify suicidal thoughts and behaviours in autistic and possibly autistic people, and model associations with risk and protective factors. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13229-021-00449-3.