An item response theory analysis of the DSM-IV borderline personality disorder criteria in a population-based sample of 11- to 12-year-old children.

Although a growing body of empirical literature provides some support for the diagnosis of borderline personality disorder (BPD) in youth, little is known about the internal structure of BPD and the performance of the individual diagnostic criteria, especially in younger samples. We used item response theory (IRT) methods to investigate the psychometric properties of the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) BPD criteria in a large, population-based sample (n = 6,339) of young adolescents from the United Kingdom (ages 11 to 12). BPD was assessed using the Childhood Interview for DSM-IV Borderline Personality Disorder (CI-BPD; Zanarini, Horwood, Waylen, & Wolke, 2004). A single underlying dimension adequately accounted for covariation among the BPD criteria. Each criterion was found to be discriminating to a degree comparable to what has been reported in adult studies. BPD criteria were most informative within a range of severity of BPD pathology between +1 and +3 standard units. Five criteria were found to exhibit differential item functioning (DIF) between boys and girls. However, DIF balanced out for the total interview score. Despite the controversy associated with applying the borderline construct to youth, the current findings provide psychometric evidence in favor of doing so.