The Interpersonal Psychological Theory of Suicide in Italian University Students: Validation of the INQ-15 and the ACSS-FAD

In the frame of the interpersonal psychological theory of suicide (IPTS), Interpersonal Needs Questionnaire (INQ-15) assesses thwarted belongingness (TB) and perceived burdensomeness (PB), related to suicidal ideation (SI); Acquired Capability for Suicide Scale–Fearlessness About Death (ACSS-FAD) measures this component which contributes to lethal self-harm. The objective was to evaluate the psychometric properties of INQ-15 and ACSS-FAD in a population of Italian university students. Since the Italian INQ-15 was already validated, we translated ACSS-FAD through a multistage procedure and administered both to 1,665 Italian university students. Factor analysis confirmed a two-factor-related model of INQ-15, one factor of ACSS-FAD, and good reliability for both. We proved the association between INQ-15 and current SI and between ACSS-FAD and lifetime suicidal planning and/or suicide attempt. The convergent and discriminant validities were in line with those of previous studies. Both tools are valid and reliable to assess the constructs associated with suicide outcomes according to IPTS.