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The SIDAS is designed to screen individuals in the community for presence of suicidal thoughts and assess the severity of these thoughts. It 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

In the past month, how often have you had thoughts about suicide? (0 = Never, 10 = Always)

In the past month, how much control have you had over these thoughts? (0 = No control, 10 = Full control)

In the past month, how close have you come to making a suicide attempt? (0 = Not close at all, 10 = Made an attempt)

In the past month, to what extent have you felt tormented by thoughts about suicide? (0 = Not at all, 10 = Extremely)

In the past month, how much have thoughts about suicide interfered with your ability to carry out daily activities, such as work, household tasks or social activities? (0 = Not at all, 10 = Extremely)

Note: Respondents who respond “0 – Never” to the first item skip all remaining items and score a total of zero.

Scoring

Total SIDAS scores are calculated as the sum of the five items, with controllability reverse scored (10=0, 9=1, …, 0=10). Total scores range from 0 to 50.

Norms & psychometric properties

Sensitivity and specificity: The SIDAS has been validated in an online survey of community-based Australian adults (18+). In this sample (n=1,352), a cut-off of 1 had sensitivity of 85.5% for suicide plans and 84.0% for suicide attempts (with 67.1% and 63.6% specificity, respectively). However, high specificity is needed to identify individuals most likely to engage in suicidal behaviour. Scores ≥21 had 95.8% specificity for presence of a suicide plan in the past year and 94.9% specificity for presence of preparation/attempt in the past year (with 39.6% and 50.0% sensitivity, respectively). Based on these results, any ideation would be indicative of risk for suicidal behaviour, while a cut-off of 21 on the SIDAS may be used to indicate high risk of suicidal behaviour.

Internal consistency: The SIDAS had high internal consistency (Cronbach alpha = 0.91).

Factor structure: In the full sample (n=1,352), all five items loaded on a single factor with an eigenvalue of 3.8 and accounting for 75.5% of total variance. In the sample with suicidal thoughts (n=560), the single factor had an eigenvalue of 3.3 and accounted for 65.5% of total variance. All items had absolute factor loadings greater than 0.6, indicating that the attributes of suicidal ideation measured appear to contribute to a unidimensional construct of suicidal ideation.

Convergent validity: The SIDAS total score had good convergent validity with the Columbia-Suicide Severity Rating Scale frequency item (r=0.61), duration item (r=0.50), and controllability item (r=0.44). Similarly, the SIDAS had good convergent validity with the Patient Health Questionnaire 9 (r=0.65), General Anxiety Disorder 7 (r=0.58), and Insomnia Severity Index (r=0.40).

Key references

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.