Abstract
Background/Objectives: The Level of Personality Functioning Scale-Brief Form 2.0 (LPFS-BF 2.0) is a self-report screening measure of personality impairments according to the DSM-5 Alternative Model for Personality Disorders and the ICD-11 classification of personality disorders. Nevertheless, reliable cut-off scores that could help in clinical decision making are still lacking for many populations. The aim of this study was to develop severity benchmarks of the LPFS-BF 2.0 for a Polish population based on the item response theory (IRT) approach. Methods: A sample of Polish adults (n = 530) took part in the study. The participants assessed their personality functioning and pathological personality traits and provided information about psychiatric diagnosis and psychotherapy seeking. The severity benchmarks were developed using IRT and validated using mean and frequency comparisons between groups of different personality impairments according to the developed cut-offs. Results: Confirmatory factor analysis (CFA) supported a unidimensional model of the LPFS-BF 2.0. The graded IRT model indicated satisfactory item functioning for all LPFS-BF 2.0 items. The normative observed score thresholds at different latent severity levels of personality impairments were developed, and significant overall differences were found between the LPFS-BF 2.0 norm-based severity benchmarks in pathological personality traits and psychotherapy seeking. Conclusions: The IRT-based cut-offs for the LPFS-BF 2.0 identified individuals high on pathological personality traits (particularly disinhibition) and were predictive of psychotherapy seeking. The developed severity benchmarks allow for the interpretation of LPFS-BF 2.0 scores, supporting clinical diagnosis and relevant decision making in the Polish population. Practical implications for healthcare practice and research are being discussed.