An 11-item measure to assess borderline traits in adolescents: refinement of the BPFSC using IRT.

Despite historical concerns about the validity of the construct of borderline personality disorder (BPD) in adolescence, there is now general consensus that BPD in adolescence constitutes a valid and reliable diagnosis. Yet the development and refinement of measures to assess borderline traits in adolescents is in its infancy. Moreover, brief and easy-to-administer measures of borderline traits for use in large-scale studies do not exist. The aim of the current study was to evaluate the Borderline Personality Features Scale for Children (BPFSC; Crick, Murray-Close, & Woods, 2005) and develop a short version of the BPFSC through the use of item response theory (IRT) methods. BPFSC data from a community sample of 964 adolescents (mean age = 15.1 years, SD = .79; 55.9% female) were used to examine the factor structure of the BPFSC. The hypothesized 4-factor structure was not supported. The unidimensional IRT analysis showed instances of local dependence among item pairs and item responses that were not strongly related to the underlying construct. As a consequence, items were eliminated, creating a unidimensional 11-item brief BPFSC (the BPFSC-11). Next, evidence of construct validity of scores based on the shortened version was evaluated using a different sample of 371 inpatient adolescents. We demonstrated similar indices of construct validity as observed for the BPFSC total score with the BPFSC-11 scores and found evidence for good criterion validity. Use of the BPFSC-11 in clinical settings will reduce the burden on respondents without loss of information.