Kiel Gender Dysphoria Questionnaire (KGDQ): development and validation of a questionnaire for change-sensitive assessment of gender dysphoria.

We developed and evaluated the Kiel Gender Dysphoria Questionnaire (KGDQ), a tool designed to assess distress due to gender incongruence in individuals aged 18 and above with sensitivity to change. The 31 items of the questionnaire were generated through semi-structured guideline interviews with trans* patients (n = 7) and experts (n = 5), which were analyzed using qualitative content analysis. Additionally, modified items from other questionnaires and the item collection of a working group were considered. Subsequently, the questionnaire was completed online by gender-dysphoric participants (N = 219). A principal axis analysis revealed a conceptually plausible three-factor structure with the subscales Alienation, Gender Role Pressure, and Body Dysphoria. All subscales demonstrated at least good internal consistency with α ≥ 0.80. A correlational comparison of two testing periods indicated high test-retest reliability (r = 0.84). The convergent validity with the Utrecht Gender Dysphoria Scale-Gender Spectrum and the divergent validity with the PHQ-9 module of the Patient Health Questionnaire were only partially demonstrated, as the predetermined thresholds were slightly under (r < 0.50) or overstepped (r > 0.40). The assessment of known-groups validity showed expected mean differences. The results suggest that the KGDQ is a reliable and valid instrument for capturing various aspects of gender dysphoria over time.