Clinically Significant Scores for Thwarted Belonging and Perceived Burden from the Interpersonal Needs Questionnaire (INQ-15).

Background: Social disconnection is associated with all-cause mortality and suicide. Measures of social disconnection with reliable cut-off scores are needed to aid in the assessment of clinically significant change. Aims: The current study sought to identify reliable clinical cut-off scores for the 15-item Interpersonal Needs Questionnaire (INQ-15), which assesses two indices of social disconnection associated with suicide ideation - thwarted belonging (TB) and perceived burden (PB) on others. Methods: The INQ-15 and measures of suicide ideation were administered to psychiatric outpatients (N_sample1 = 493; N_sample2 = 213) and psychiatric inpatients (N_sample3 = 79; N_sample4 = 87). Results: Reliable cut-off scores discriminating between the presence and absence of suicide ideation were identified across samples (TB ≥ 36 for psychiatric outpatients and ≥ 32 for inpatients; PB ≥ 12 for both psychiatric outpatients and inpatients). Limitations: Data are cross-sectional; thus, conclusions cannot be made about the predictive utility of INQ scores for future suicide ideation, attempts, or death. Conclusions: The INQ-15 yields scores with reliable cut-off scores for both TB and PB that represent clinically significant levels of social disconnection. These cut-off scores can be used in treatment trials and clinical practice to assess clinical improvement (or decline) in belonging and perceived burden.