Relevance of the interpersonal theory of suicide in an adolescent psychiatric inpatient population

•The interpersonal psychological theory of suicide is understudied in adolescents.•This study tested if IPTS variables relate to suicidality on hospital admission.•It also tested if they predict rehospitalization or suicide attempt within 90 days.•We found that IPTS constructs associated with suicidality on admission.•IPTS constructs did not predict rehospitalization or suicide attempt. The interpersonal theory of suicide (IPTS) has been widely studied in adults, but not adolescent populations at acute risk for suicide. Accordingly, this study aimed to evaluate IPTS clinical utility in a high-risk sample of suicidal adolescent inpatients. We assessed whether constructs of the IPTS (1) are associated with suicidal thoughts and behaviors (STBs) on admission to a psychiatric hospitalization, and (2) prospectively predict suicide attempt (SA) or psychiatric rehospitalization 90 days after discharge. On admission, adolescent patients self-reported recent STBs, perceived burdensomeness (PB), thwarted belongingness (TB), and depression. Parents reported their child's rehospitalization and suicide attempts 90 days after discharge. Generalized linear regression modelling was used to determine how key constructs of the IPTS are associated with STBs prior to admission and whether they prospectively predict SA or rehospitalization 90 days after discharge. IPTS constructs did not predict rehospitalization or SA within 90 days of discharge. Although PB and TB interacted to associate with prehospitalization SI frequency, and PB, TB and NSSI interacted to associate with prehospitalization SA, the nature of these interactions were not as the IPTS predicts. IPTS constructs are relevant proximal predictors of prehospitalization STB in adolescents, but may operate differently than in adults.