LAUSR

Multiple informant assessment is the norm when evaluating borderline personality pathology (BPP) in adolescence, especially by including reports from both parents and adolescents. However, these reports tend to be discrepant, and it is unclear how to integrate. The current study used a trifactor model to isolate sources of variance in parents' and adolescents' reports of BPP due to their shared and unique perspectives in a sample of 652 inpatient adolescents (63% female; Mage = 15.31, SD = 1.45) and their parents (81% mothers). Consensus/agreement was characterized by the externalizing features of BPP whereas idiosyncratic views of adolescent BPP covered the full latent BPP construct, suggesting that simple aggregation of parent and adolescent reports is inappropriate. Measurement invariance suggested that unique perspectives were characterized by slightly different operationalizations of BPP and response biases for specific features of BPP. Attachment security and parents' interpersonal problems predicted shared and unique perspectives differently for female and male adolescents. Lastly, we found that shared and unique perspectives differentially predicted interview based BPP, length of stay, and adolescent mentalizing. In sum, findings replicate previous evidence of parent-child informant discrepancy in youth psychopathology, broadly, and provide insights specific to BPP. Discussion includes practical recommendations for assessment and interpretation of BPP assessment.