Measurement Properties of the Suicide Behaviours Questionnaire - Revised in Autistic Adults.

Background: The Mental Health in Autism project (MHAutism) aims to develop a new suicidality assessment tool for autistic adults – a group at high risk for dying by suicide. Our systematic review found no studies exploring suicidality in autistic adults had yet used a tool with evidence of validity, and no suicidality assessment tool had yet been developed for this group. However, we identified the Suicidal Behaviours Questionnaire – Revised (SBQ-R) as a promising candidate tool to adapt for autistic adults. The current study explores the appropriateness and psychometric properties of the SBQ-R in autistic compared to general population adults, to inform future adaptations.

Objectives: First, to explore whether the SBQ-R similarly captures the same latent construct (suicidality) in autistic compared to general population adults. Second, to explore how autistic adults interpret and respond to the items of SBQ-R.

Methods: First, 188 autistic adults (76 male) and 183 general population adults (62 male) completed the SBQ-R online. Multi-group factorial invariance (MFI) analysis compared the structural equivalence of the SBQ-R between the groups. Cognitive interviews subsequently explored how a sub-group (n = 15) of autistic adults interpreted and responded to the items of the SBQ-R.

Results: MFI analysis of the online survey data found evidence for configural but not metric invariance of the SBQ-R, with significantly different factor loadings between groups for items three (communication of suicide threat to others) and four (future suicidal intent) of the questionnaire. Consistent with these findings, cognitive interviews revealed different interpretation of questions requiring abstract future thinking, social and communication skills, and absence of items which captured the unique presentation of suicidality in autism.

Conclusions: Findings suggest that autistic adults attribute a different meaning to some items on the SBQ-R compared to general population adults, and absence of items which capture the unique presentation of suicidality in autism. These results will be used to adapt the SBQ-R to better capture suicidality in autistic adults.