Psychometric Properties of the Greek Version of the BPDSI-IV: Insights into Borderline Personality Disorder Severity.

Background: Borderline Personality Disorder (BPD) is a growing health concern, characterized by emotional dysregulation, impulsivity, and unstable interpersonal relationships. One of the core features of BPD is self-harm, which has significant implications for clinical management, risk assessment, and treatment planning. Accurate assessment tools are essential in evaluating symptom severity and identifying individuals at high risk of self-injurious behaviors, thereby guiding clinical interventions effectively. This study aimed to assess the psychometric properties, factor structure, and diagnostic utility of the Greek version of the Borderline Personality Disorder Severity Index-IV (BPDSI-IV), providing preliminary evidence for its reliability and validity. Methods: A total of 128 individuals with BPD and 32 healthy controls were assessed using the BPDSI-IV together with the Brief Symptom Inventory-53 (BSI-53), the BPD Checklist, the Rosenberg Self-Esteem Scale, the WHOQOL-BREF, and the Defense Style Questionnaire-40 (DSQ-40). BPD diagnoses were confirmed using the Structured Clinical Interview for DSM-5 Personality Disorders (SCID-5-PD). Internal consistency, confirmatory factor analysis (CFA) of previously suggested models, exploratory and confirmatory bifactor modeling, and validity assessments were conducted. Results: The BPDSI-IV showed strong internal consistency (α = 0.92, ωt = 0.96), with most subscales demonstrating adequate reliability. Exploratory bifactor analysis using the Schmid-Leiman transformation supported a model with a dominant severity factor (ωh = 0.69), reinforcing the dimensional nature of BPD. CFA supported this bifactorial approach. BPDSI-IV scores significantly discriminated BPD patients from controls (p < 0.001). Strong correlations with measures of psychopathology and self-esteem, and correlations with quality of life further supported its validity. Conclusions: The Greek BPDSI-IV demonstrated strong reliability and validity indicators. Structured assessment tools, such as the BPDSI-IV, can enhance early intervention and research on the course of borderline personality disorder symptoms.