Longitudinal risk profiling for suicidal thoughts and behaviours in a community cohort using decision trees

Background: While associations between specific risk factors and subsequent suicidal thoughts or behaviours have been widely examined, there is limited understanding of the interplay between risk factors in the development of suicide risk. This study used a decision tree approach to develop individual models of suicide risk and identify the risk factors for suicidality that are important for different subpopulations. Methods: In a population cohort of 6656 Australian adults, the study examined whether measures of mental health, physical health, personality, substance use, social support, social stressors and background characteristics were associated with suicidal ideation and suicidal behaviours after four-year follow-up. Results: Previous suicidality, anxiety symptoms, depression symptoms, neuroticism and rumination were the strongest predictors of suicidal ideation and behaviour after four years. However, divergent factors were predictive of suicidal thoughts and behaviours across the spectrum of mental health. In particular, substance use was only associated with suicidal thoughts and behaviours in those with moderate levels of anxiety or depression. Limitations: Most of the measurements were based on self-report. Further research is required to assess whether changes in risk factors lead to changes in suicidality. Conclusions: Examining suicide risk factors using decision trees is a promising approach for developing individualised assessments of suicide risk and tailored intervention programs.