Chronic skin diseases and life trajectories: Development and validation of “Dermatology Long-Term Life Impact Measure”

BACKGROUND: To date, tools evaluating the impact of skin diseases on quality of life have investigated short-term impact, overlooking the long-term effects on important life decisions. OBJECTIVE: To create and validate the "Dermatology Long-Term Life Impact Measure (DLLIM)" questionnaire, which assesses the impact of six chronic inflammatory skin diseases on an individual's life decisions. METHODS: Following COnsensus-based Standards for the selection of health Measurement INstruments guidelines, we developed and validated DLLIM through item refinement and psychometric testing in a sample of 16,727 patients with chronic skin diseases. Factorial and construct validity were assessed, alongside internal consistency using Cronbach's alpha. Cross-cultural validation was performed in 10 languages. RESULTS: Eleven items covering education, work, and emotional life demonstrated strong unidimensionality (comparative fit index: 0.96, root mean square error of approximation: 0.071) and high internal consistency (Cronbach's α = 0.966). DLLIM scores correlated strongly with stigmatization scores (Patient Unique Stigmatization Holistic tool in dermatology), supporting construct validity. LIMITS: The majority of patients had atopic dermatitis (n = 15,223), which might limit generalizability. CONCLUSION: DLLIM is a valid, reliable instrument for measuring the long-term impact of chronic skin diseases on life decisions. It fills a gap in dermatological quality-of-life assessment and supports patient-centered care.