Investigating differential item functioning among borderline personality disorder diagnostic criteria and internalizing/externalizing domains based on sexual orientation.

Borderline personality disorder (BPD) is more frequently diagnosed among sexual minority (SM) populations. SM populations also report higher levels of internalizing and externalizing psychopathology, two core domains of clinical problems that are highly comorbid with BPD. Contextual factors (e.g., group-specific norms) might affect endorsement of BPD items for reasons other than an underlying liability to experience BPD or internalizing and externalizing psychopathology. Therefore, BPD items may be "easier" to endorse (i.e., be associated with lower indicator thresholds) for SM populations relative to non-SM populations. We tested this hypothesis in a large, nationally representative sample of the U.S. population (