This study aims to develop and provide preliminary reliability and validity of a questionnaire to measure Health-related Quality of Life (HRQOL) in adolescents with psoriasis. To the best of our knowledge, this will be the first psoriasis-specific HRQOL instrument for use in adolescent patients. Data will be collected from a Danish population of adolescents with psoriasis (12-17 years), as well as from parents of adolescents with psoriasis, and a group of adolescents without psoriasis.

The present study will examine the psychometric properties of a preliminary 41-item version of the PsoTeenQOL. The preliminary PsoTeenQOL has been developed based on qualitative interviews of adolescents (12-17 years) with psoriasis, their parents, and health professionals working within the field, as well as literature reviews and existing questionnaires. Face and content validity has been established through subsequent cognitive interviews with the target group.

Exploratory factor analysis (EFA) and analysis of differential item functioning (DIF) will be used to further refine the PsoTeenQOL questionnaire by selecting the most appropriate items. In addition, indicators of reliability (internal consistency; test-retest reliability), validity (construct validity, criterion validity; discriminant validity), and responsiveness will be evaluated.

Inclusion Criteria:

• Either a) Subjects with psoriasis, b) Parents of adolescents 12-17 years with psoriasis, or c) Subjects without psoriasis
• Ability to read Danish and complete electronic survey

Exclusion Criteria:

• Inability to read Danish and complete electronic survey

To achieve maximum variation in participant demographic and clinical characteristics, eligible participants with psoriasis plus their parents will be identified through several sites; a) the Danish Psoriasis Association, b) the National Danish Birth Cohort, and c) all five tertiary hospital clinics in Denmark. All adolescents without psoriasis will be recruited from the National Danish Birth Cohort.