Measurement Invariance of the Level of Personality Functioning Scale-Brief Form 2.0 in Treatment-Seeking and Non-treatment-Seeking Groups.

The Level of Personality Functioning Scale-Brief Form 2.0 (LPFS-BF 2.0) was developed as a screening tool for personality functioning. Its generalizability and comparability across groups with diverse mental health histories have not been explored yet. This study examined configural, metric, scalar, and strict measurement invariance of the scale between treatment-seeking (n = 1113) and non-treatment-seeking (n = 690) groups. Results supported the invariance of the two-factor structure of the LPFS-BF 2.0 and demonstrated good psychometric properties in both groups. The findings provide evidence of the generalizability and construct equivalence of the LPFS-BF 2.0. The scale effectively captured both healthy functioning and disturbances. Associations with the severity of psychopathology symptoms and meaningful differences in severity classification across groups further supported its validity. At the same time, findings suggested that LPFS-BF 2.0, especially self-functioning, might be an overall indicator of mental health difficulties severity rather than being specific to the severity of personality dysfunction.