Globally, 34.6 million years of life are lost from suicide annually. Protective factors are thought to lower suicide risk or help a person defend against suicidal thoughts. However, it is currently unclear how protective factors for suicide interact with established risk factors to disrupt the developmental pathways from suicidal thoughts to behaviours. 

This study used Decision Tree (DT) analysis to identify the most relevant protective and risk factors in predicting suicidality in the general population. 

Online quota sampling was used to recruit 1,187 Australian adults (54.3% women; M age = 46.76 years, SD = 18.44) from market research panels to participate in an anonymous online survey. Sociodemographic information and a range of empirically and theoretically supported protective and risk factors for suicide were measured in relation to past month suicide ideation and attempt. A DT model with 41 protective and risk factors was built using the Chi-Square Automatic Interaction Detector algorithm. 

Two thirds (65.5%) of participants reported no suicidality, 16% ideation only (SI), and 18% both ideation and attempts (SI and SA). The DT model identified 18 different protective and risk profiles. Perceived burden (PB) was the strongest predictor of past month suicidality. 

Out of 41 protective and risk factors measured, low PB – comprising low feelings of self-hatred and liability to others – was found to be most protective against suicidality. Significance: The 18 different subgroups identified in the study highlight the complexity of interrelationships between suicide protective and risk factors and aid in the identification of risk profiles for suicidal behaviour.