Factorial and Convergent Validity of the Short Form of the "Questionnaire of Thoughts and Feelings" (QTF-14) for Borderline Personality Disorder

The "Questionnaire of Thoughts and Feelings" (QTF) is being used as screening instrument as well as tool for treatment planning and treatment evaluation for patients with borderline personality disorder (BPD). The primary goal of this study was the validation of the dimensional structure of the short version with 14 items, QTF-14. Additionally, item characteristics, reliability and evidence of convergent validity were examined. A diagnostically homogenous sample of patients with BPD (N=3035) of a psychosomatic clinic was presented with several self-assessment inventories, including the QTF-14. The expected single-factor model of the structure of the FGG showed unacceptable model fit indices (CFI=0.751; TLI=0.706; RMSEA=0.115; SRMR=0.073). Exploratory factor analysis showed evidence of two or three specific factors. In a subsequent confirmatory factor analysis, a bifactor model with two specific factors proved to be preferable (CFI=0.956; TLI=0.936; RMSEA=0.054; SRMR=0.034). The internal consistency of the total scale as well as the suggested subscales "Relationship Difficulties and Emotional Dysregulation" and "Autoaggression" was acceptable to good (omega=.81-.84; alpha=.79-.85). Associations with similar scales were as expected. Good psychometric properties of the QTF-14 can be confirmed in this study. Using the suggested subscales could support treatment planning.