Predicting suicide attempt and suicide : the role of standardised instruments in a psychiatric cohort

Abstract

Aim: The aim of this thesis was to assess the role of standardised instruments in prediction of suicide attempt and suicide in patients known to have an increased risk of these outcomes, namely patients with self-harm.

Method: The predictive abilities of four instruments focusing on different factors related to suicide risk were estimated using a sample of patients with a recent episode of self-harm with or without suicidal intent (N=804) who took part in a prospective, observational multi-centre study. Patients were identified at psychiatric or medical emergency departments and interviewed by research staff not engaged in the regular clinical management. The outcomes of interest were suicide attempt and suicide within one year of the index episode. Follow-up data was collected from medical records and the National Cause of Death Register. Correlations between total scores of the instruments (or dichotomised total scores) and the outcomes were evaluated using the χ2-test, logistic regression and receiver operating characteristic curves. The Karolinska Interpersonal Violence Scale (KIVS) was used to assess experience of interpersonal violence, and the total score was examined as a predictor of repeat non-fatal or fatal attempt within six months in 355 participants included after a suicide attempt from 2012 to 2014 (Study I). The Columbia-Suicide Severity Rating Scale (C-SSRS) was used to assess suicidal ideation and behaviour and examined as a predictor of repeat non-fatal or fatal attempt within six months in the full sample (N=804) included between 2012 and 2016 (Study II). The KIVS, the C-SSRS, the Suicide Intent Scale (SIS) and the Suicide Assessment Scale (SUAS) were compared regarding predictive accuracy measures for suicide attempt and suicide as separate outcomes within three months and one year (Study III). The predictive accuracy of the clinical suicide risk assessment was compared to that of SIS in a subset of the sample (n=479) for the outcome suicide within one year (Study IV).

Results: The non-fatal one-year repetition rate was 27% and the fatal repetition rate was 2.4%. Statistically significant correlations were found between the total scores of the KIVS, the C-SSRS and the SUAS and non-fatal suicide attempts within six months and one year follow-up (Study I, II and III). Predictive accuracy was limited for all instruments. The same applied to the SIS total score predicting suicide within three months and one year (Study III). The predictive abilities were very similar for the SIS and the clinical risk assessment regarding suicide during one-year follow-up, again with limited accuracy measures (Study IV).

Conclusions: Due to limited accuracy measures and the low base rates of suicide attempt and suicide, these instruments cannot be of clinically practical use in the prediction of suicide attempt and suicide on an individual level. Other potential areas of usage for the instruments, such as structuring clinical data, exploring specific experiences or monitoring symptoms, remain to be examined.