The Suicidal Ideation Attributes Scale-Modified (SIDAS-M): Development and preliminary validation of a new scale for the measurement of suicidal ideation in autistic adults
Authors: Hedley Darren , Batterham Philip J , Bury Simon M , Clapperton Angela , Denney Kathleen , Dissanayake Cheryl , Fox Phoenix , Frazier Thomas W , Gallagher Emma , Hayward Susan M , Robinson Jo , Sahin Ensu , Trollor Julian , Uljarević Mirko , Stokes Mark A 
Published: October 2022

The study describes the development and preliminary psychometric validation of the Suicidal Ideation Attributes Scale-Modified (SIDAS-M), a five-item assessment of suicidal ideation for use with autistic adults. Participants ( n  = 102 autistic adults; 58% women, 34% men, 8% nonbinary; Mage  = 41.75, SD  = 12.89) completed an online survey including the SIDAS-M at Time 1 and participated in follow-up interviews at Time 2 (~111 days later). A single factor solution provided good to excellent fit to the data (comparative fit index = 0.961, Tucker–Lewis index = 0.921; standardized root mean square residual = 0.027), with all items showing good to excellent loadings (0.74–0.91). SIDAS-M total score (ω=.930, bias-corrected and accelerated 95% confidence interval (BCa 95% CI) [.90, .95]) demonstrated good convergent validity, correlating significantly with existing suicide specific (ρ=.442–.698, p<.001) and well-being measures (ρ=.325.–.505, p≤.001), and good divergent validity. Logistic regression controlling for age, gender, and relationship status indicated that SIDAS-M scores at Time 1 significantly predicted suicidal behavior at Time 2, β  = 0.462, p < 0.001, [0.032, 0.068]. Receiver operating characteristic curve analysis indicated SIDAS-M has utility discriminating between participants classified at low or above low risk, area under the curve = 0.866, [0.767, 0.966], p  < 0.001, with a cutoff score ⩾1 providing a potentially useful indicator of increased suicidal risk. Overall, SIDAS-M demonstrated good psychometric properties when used with autistic adults without intellectual disability. Lay Abstract Autistic people may be at higher risk of suicidal behavior than people in the general population. Suicidal behavior may include thinking about suicide or attempting to end one’s own life by suicide. It is important to identify autistic people who may be thinking about suicide. People who are at risk of suicidal behavior can be identified by asking questions about whether they have been thinking about suicide. A specially designed questionnaire, or screening instrument, can help someone ask the best questions to find out if someone has been thinking about suicide. This information can help to identify supports to be put in place to prevent suicidal behavior, such as a suicide attempt. However, autistic people may interpret questions differently than non-autistic people. It is important to use screening tools that have been designed with, and for autistic people. In this study, we examined the Suicidal Ideation Attributes Scale (SIDAS). The SIDAS is an existing tool that was developed to screen for suicidal thinking in the general population. We modified SIDAS for use with autistic adults. We involved autistic people in the process of modifying SIDAS. We called the modified instrument the SIDAS-M. The results of our study showed SIDAS-M may be useful for screening for suicidal thinking in autistic adults who do not have an intellectual disability.