Reliability and Longitudinal Course of Itch/Scratch Severity in Adults With Atopic Dermatitis.

BACKGROUND: Itch is a complex and burdensome symptom in atopic dermatitis (AD). Severity of scratching/excoriation (SCORAD-scratch) has been found to be a valid measure of itch in AD. However, little is known about the longitudinal course of scratching/excoriations in AD. METHODS: A prospective, dermatology practice-based study was performed of adults with AD (N = 399). The patients were assessed at baseline and approximately 6, 12, 18, and 24 months. RESULTS: Severity of excoriations correlated best with the Numerical Rating Scale-worst itch (Spearman correlation, ρ = 0.50), followed by a Patient-Reported Outcome Measurement Information System Itch Questionnaire-scratching behavior T score (ρ = 0.48), Numerical Rating Scale-average itch (ρ = 0.41), relative frequency of itch (ρ = 0.36), and frequency of itch from eczema (ρ = 0.29, all P < 0.0001). Scratching severity showed good reliability (intraclass correlation coefficient range = 0.62-0.69). Overall, 30.6% and 5.5% had moderate (2) or severe (3) SCORAD-scratch scores. Among patients with baseline moderate (2) or severe (3) SCORAD-scratch scores, 18.9% and 13.6% continued to have moderate or severe scores at 1 or more follow-up visits. In repeated-measures regression models, persistent SCORAD-scratch scores were associated with baseline severity of excoriations (adjusted ß [95% confidence interval] = 0.51 [0.37 to 0.65]), Medicaid insurance (-0.35 [-0.65 to -0.04]), and Eczema Area and Severity Index scores (0.03 [0.02 to 0.04]). CONCLUSIONS: Adult AD patients had a heterogeneous longitudinal course with fluctuating severity of excoriations.