Measurement invariance and validation of the LPFS-BF 2.0 in clinical and community samples of Turkish adolescents

Background
Given the limited number of validation studies on the LPFS-BF 2.0 in adolescents and scarce test–retest data, the current study aimed to examine the psychometric properties of the Turkish version of the LPFS-BF 2.0 in adolescents.

Methods
The scale was translated in accordance with International Test Commission guidelines and administered to 170 clinical and 184 community adolescents aged 12–18 years (N = 354). Exploratory factor analyses (EFA) were conducted separately in the two groups using Principal Axis Factoring (PAF). Factor retention was evaluated using eigenvalues greater than 1, scree plot inspection, and Horn’s parallel analysis, followed by confirmatory factor analysis (CFA) to test the theoretically expected two-factor structure. Multi-group confirmatory factor analysis was used to examine measurement invariance across clinical and community samples. Internal consistency was assessed using Cronbach’s alpha, convergent validity was evaluated through correlations with the Brief Symptom Inventory (BSI), Borderline Personality Features Scale for Children–Short Form (BPFSC-SF), Personality Belief Questionnaire–Short Form (PBQ-SF), and number of psychiatric diagnoses, and test–retest reliability was examined in a clinical subsample.

Results
EFA revealed a two-factor structure in the clinical sample and a three-factor structure in the community sample. Horn’s parallel analysis supported a two-factor structure in both samples, and CFA confirmed the two-factor model reflecting self- and interpersonal functioning, with acceptable fit indices in both groups. Measurement invariance analyses indicated configural, metric, and partial scalar invariance across the two samples, supporting the comparability of the scale across diagnostically distinct adolescent groups. Internal consistency was acceptable to good in the clinical group (α = 0.72–0.83) and somewhat lower in the community group (α = 0.61–0.79). LPFS-BF 2.0 scores showed significant positive associations with theoretically related constructs, including borderline personality features, maladaptive personality beliefs, and psychological distress, providing support for convergent validity. Test–retest reliability in a subsample of clinical participants yielded moderate correlations over a six-month interval (r = 0.46–0.51).

Conclusions
Overall, the findings support the Turkish LPFS-BF 2.0 as a brief, reliable, and valid measure of self- and interpersonal functioning in adolescents, consistent with the DSM-5 Section III conceptualization of personality pathology. The results further suggest that the scale functions similarly across clinical and community samples and may be useful in both research and clinical settings.