Short term risk of non-fatal and fatal suicidal behaviours: the predictive validity of the Columbia-Suicide Severity Rating Scale in a Swedish adult psychiatric population with a recent episode of self-harm

Background: The Columbia-Suicide Severity Rating Scale (C-SSRS) is a relatively new instrument for the assessment of suicidal ideation and behaviour that is widely used in clinical and research settings. The predictive properties of the C-SSRS have mainly been evaluated in young US populations. We wanted to examine the instrument's predictive validity in a Swedish cohort of adults seeking psychiatric emergency services after an episode of self-harm. Methods: Prospective cohort study of patients (n = 804) presenting for psychiatric emergency assessment after an episode of self-harm with or without suicidal intent. Suicidal ideation and behaviours at baseline were rated with the C-SSRS and subsequent non-fatal and fatal suicide attempts within 6 months were identified by record review. Logistic regression was used to evaluate separate ideation items and total scores as predictors of non-fatal and fatal suicide attempts. Receiver operating characteristics (ROC) curves were constructed for the suicidal ideation (SI) intensity score and the C-SSRS total score. Results: In this cohort, the median age at baseline was 33 years, 67% were women and 68% had made at least one suicide attempt prior to the index attempt. At least one non-fatal or fatal suicide attempt was recorded during follow-up for 165 persons (20.5%). The single C-SSRS items frequency, duration and deterrents were associated with this composite outcome; controllability and reasons were not. In a logistic regression model adjusted for previous history of suicide attempt, SI intensity score was a significant predictor of a non-fatal or fatal suicide attempt (OR 1.08; 95% CI 1.03-1.12). ROC analysis showed that the SI intensity score was somewhat better than chance in correctly classifying the outcome (AUC 0.62, 95% CI 0.57-0.66). The corresponding figures for the C-SSRS total score were 0.65, 95% CI 0.60-0.69. Conclusions: The C-SSRS items frequency, duration and deterrents were associated with elevated short term risk in this adult psychiatric cohort, as were both the SI intensity score and the C-SSRS total score. However, the ability to correctly predict future suicidal behaviour was limited for both scores.