Development and Initial Psychometric Properties of Two Itch-Related Measures: Scratch Intensity and Impact, Sleep-Related Itch and Scratch

Self-report measures are needed to better understand the relationships among sleep, itching, scratching, and chronic itch conditions and their associations with disease severity, QOL, health, and functioning. Two scales related to sleep and/or scratch were recently developed and assessed in 137 patients with chronic itch and atopic dermatitis or psoriasis. The Scratch Intensity and Impact Scale consisted of two factors (scratching intensity and impact of scratching on QOL) that accounted for 64.59% of the variance with a total of 13 items, overall Cronbach's α of 0.93, and test–retest reliability of 0.66. The Sleep-Related Itch and Scratch Scale consisted of one factor that accounted for 63.01% of the variance with a total of 16 items, overall Cronbach's α of 0.98, and test–retest reliability of 0.66. Both measures demonstrated significant correlations with each other as well as other itch-related measures and nonsignificant correlations with scales hypothesized to be unrelated. The final measures demonstrated adequate preliminary psychometric characteristics. It is hoped that these scales will be used for future research and clinical purposes to help fill recognized gaps in understanding about sleep, itch, scratching, atopic dermatitis, and psoriasis.