Testing the Four Main Predictions of the Interpersonal-Psychological Theory of Suicidal Behavior in an Inpatient Sample Admitted Due to Severe Suicidality

This study aimed to evaluate four main predictions of the Interpersonal Psychological Theory of Suicide (IPTS): the importance of perceived burdensomeness (PB), thwarted belongingness (TB), hopelessness (H), and capability for suicide (CS) for (passive/active) suicide ideation, suicide intent and suicide attempts. N = 308 psychiatric inpatients admitted due to severe suicidality (53.6% female: n = 165; age: M = 36.82, SD = 14.30, range: 18-81) completed self-report measures of TB, PB, H, CS and suicide ideation as well as interviews on suicide intent and suicide attempts. TB and PB were associated with (passive/active) suicidal ideation, whereas the three-way interaction PB, TB, and H was not associated with active suicide ideation. Fearlessness about death in conjunction with active suicidal ideation was not associated with suicide intent and the interaction of PB, TB, and CS was neither predictive of recent suicide attempt status nor lifetime number of suicide attempts. Given the cross-sectional nature of the data, conclusions on causality should be handled carefully. The results challenge the theoretical validity of the IPTS and its clinical utility-at least within the methodological limitations of the current study. Yet, findings underscore the importance of PB in understanding suicidality.