Comparing the measurement properties, informativity and responsiveness of the DLQI, DLQI-Relevant (DLQI-R), and Skindex-29 in patients with chronic skin disease: a prospective cohort study.

PURPOSE: Patient-reported outcome measures (PROMs) are important tools for assessing the impact of skin diseases on health-related quality of life (HRQoL). However, comparative data on the measurement properties of commonly used instruments are limited. The objective of this study was to compare the measurement properties of the Dermatology Life Quality Index (DLQI), DLQI-Relevant (DLQI-R), and Skindex-29 in a cohort of patients with chronic skin disease.

METHODS

Participants completed the DLQI, Skindex-29, and Patient-Reported Outcomes Measurement Information System (PROMIS) measures at baseline and 3 months. Structural validity was assessed with confirmatory factor analysis; internal consistency with Cronbach's alpha; construct validity via known-groups comparisons and PROMIS correlations; informativity with Shannon's index; and responsiveness with standardized response means, Cohen's d, and change score correlations.

RESULTS

Of 549 participants (mean age 37.8 years; 52.3% female), 406 (74.0%) completed follow-up. All instruments demonstrated high internal consistency (α ≥ 0.85) and no floor or ceiling effects. Skindex-29 domains demonstrated stronger structural validity and informativity compared to DLQI and DLQI-R. Construct validity was supported by expected associations with patient global assessment (PtGA) and PROMIS correlations. The DLQI, DLQI-R, and Skindex Symptoms and Emotions showed moderate responsiveness.

CONCLUSIONS

The DLQI, DLRI-R and Skindex-29 demonstrated strong measurement properties in a heterogeneous cohort of individuals with chronic skin disease. Skindex-29 showed stronger structural validity and informativity, while the DLQI and DLQI-R demonstrated slightly greater responsiveness. Selection of PROM should depend on the intended clinical or research purpose.