Skin care by washing with water is not inferior to washing with a cleanser in children with atopic dermatitis in remission in summer: WASH study.

Background: Washing with water is not inferior to washing with soaps and detergents in children with atopic dermatitis (AD) in remission during the fall-winter seasons. We investigated whether this finding varies during summer based on the type of cleanser (soaps and detergents).

Methods: This evaluator-blinded, pragmatic, randomized, and non-inferiority study enrolled patients with AD whose eczema was controlled following regular steroid ointment application 2 days/week. For 8 ± 4 weeks, participants washed their upper and lower limbs with a cleanser on one side and with water alone on the other. Each participant chose either a weakly alkaline soap or an acidic detergent. The primary outcome was the Eczema Area and Severity Index (EASI) score at week 8 ± 4.

Results: The data of 43 of the 47 registered participants were analyzed. The median patient age was 44 (23-99) months; 28 and 15 participants chose weakly alkaline and acidic cleansers, respectively. At week 8 ± 4, EASI scores of the water and cleanser sides were 0.00 (0.00-0.40) and 0.15 (0.00-0.40), respectively (p = 0.74). The difference between both sides was 0.00 (-0.07 to 0.14); the limits of the 95 % confidence interval did not reach the pre-specified non-inferiority margin. No difference was observed in the median Patient-Oriented Eczema Measure score, number of additional steroid ointment applications, and occurrences of skin infections. There were no differences between the cleanser types in any of the results.

Conclusions: We demonstrated that washing with water was not inferior to that with a cleanser in patients with AD in the maintenance phase during summer, regardless of the type of cleanser.