Suicidal Ideation Attributes Scale, Modified (SIDAS-M)
Usage: No permission required – please cite reference.
The SIDAS-M is based on the SIDAS (Van Spijker et al., 2014) and is designed to screen autistic adults in the community for presence of suicidal thoughts and assess the severity of these thoughts. The SIDAS-M was developed through a process of consultation with autistic people, researchers, and suicide prevention experts. Modifications to the original SIDAS includes revision of questions to use concrete language to avoid ambiguity in responding and addition of visual analogue scales and response exemplars. SIDAS-M would also be suitable for use by other adults who might benefit from these revisions. Consistent with the original scale, SIDAS-M consists of five items, each targeting an attribute of suicidal thoughts: frequency, controllability, closeness to attempt, level of distress associated with the thoughts and impact on daily functioning. Responses are measured on a 10-point scale. Items are coded so that a higher total score reflects more severe suicidal thoughts.
Suicidal ideation attributes scale-modified
Total SIDAS-M scores are calculated as the sum of the five items (no reverse scoring). Total scores range from 0 to 50.
Norms & psychometric properties
Sensitivity and specificity: The SIDAS-M has been validated in a sample of 102 (59% women) Australian autistic adults (18+) who did not have any co-occurring intellectual disability. In this sample (n = 98), a cut-off of 1 had sensitivity of 100% (with 52.8% specificity) for individuals identified as being above low risk of suicidal behaviour (vs. low risk) based on best estimate clinical judgement. To increase specificity, a higher score indicated in the original SIDAS was reviewed. Scores ≥21 had 89.9% specificity (with 55.6% sensitivity) for clinician identified suicide risk. Sensitivity (77.8%) and Specificity (75.3%) were maximized for scores ≥9. Based on these results, any ideation would be indicative of risk for suicidal behaviour, while a higher cut-off may be more appropriate for research purposes.
Internal consistency: The SIDAS-M had high internal consistency, McDonald’s omega = 0.93, 95% CI [.90, .95].
Factor structure: In the full sample (n=102), a single factor solution on the SIDAS-M provided good to excellent fit to the data (CFI = .961, TLI = .921; SRMR = .027). All items showed good to excellent loadings ranging from .74 to .91, indicating that the attributes of suicidal ideation measured appear to contribute to a unidimensional construct of suicidal ideation consistent with the original SIDAS.
Convergent validity: The SIDAS-M total score had good convergent validity with the Columbia-Suicide Severity Rating Scale severity (ρ = 0.442, p < .002) and intensity (ρ = 0.464, p < .002) subscales. Similarly, the SIDAS-M had good convergent validity with the Patient Health Questionnaire 9 (ρ = 0.505, p < .002), Suicide Behaviors Questionnaire-Revised (ρ = 0.698, p < .002), and Depression, Anxiety and Stress Scale-21 (ρ = 0.325–0.419, p < .002).
Hedley, D., Batterham, P. J., Bury, S. M., Clapperton, A., Denney, K., Dissanayake, C., Fox, P., Frazier, T. W., Gallagher, E., Hayward, S. M., Robinson, J., Sahin, E., Trollor, J., Uljarević, M., & Stokes, M. A. (2022).The Suicide Ideation Attributes Scale-Modified (SIDAS-M): Development and preliminary validation of a new scale for the measurement of suicidal ideation in autistic people. Autism. Advance online publication. https://doi.org/10.1177/13623613221131234
Van Spijker, B.A.J., Batterham, P.J., Calear, A.L., Farrer, L., Christensen, H., Reynolds, J. & Kerkhof, A.J.F.M. (2014). The Suicidal Ideation Attributes Scale (SIDAS): Community-based validation study of a new scale for the measurement of suicidal ideation. Suicide and Life-Threatening Behavior, 44 (4), 408-419. https://doi.org/10.1111/sltb.12084
Centre for Mental Health Research (ANU)
Olga Tennison Autism Research Centre (La Trobe University)
Darren Hedley (Principal developer)
Philip Batterham (Co-developer)