Method: In this cross-over trial, 40 patients with moderate-to-severe AD were randomized to receive twice-weekly bleach and water baths, each for 4 consecutive weeks with a 4-week washout period in between. Condition of S. aureus growth and SCORing Atopic Dermatitis index (SCORAD) were recorded at baseline and 4-weekly intervals. Patients’ blood was collected in first and second visits to investigate blood eosinophil count, serum levels of total IgE and specific IgEs against Staphylococcal enterotoxins A and B. In every visit, Children Dermatology Life Quality Index (CDLQI), skin hydration (SH), transepidermal water loss (TEWL), usage frequency of prohibited medications (topical antibiotic, steroid and oral antihistamine) were recorded.
Results: All 40 patients completed the trial, but 14 were non-adherent. By intention-to-treat (ITT) approach, comparing with water baths, bleach baths conferred no significant efficacy in CDLQI, SH, TEWL, blood eosinophil count, total IgE and the two specific IgEs over 4 weeks. Water baths caused a greater reduction in affected area of SCORAD than bleach baths (-5.7±15.4 for water vs. 0.6±12.4 for bleach; p=0.03) by ITT, and in objective SCORAD and affected area (p<0.05) from per-protocol approach. Bleach baths reduced topical corticosteroid use (mean difference=1.1±2.6 days/week; p=0.014) and topical antibiotic use (mean difference=1.0±2.8 days/week; p=0.044) in within group analysis.
Conclusion: This study demonstrated that a 4-week, twice-weekly regime of diluted bleach baths is not more useful than water baths in reducing S. aureus colonization/infection and improving AD. A longer treatment period is needed to evaluate if the short treatment duration was the main cause for the discrepancy in outcome from other bleach-bath trials. The usage of a portable bath tub obviates the problems associated with unavailability of bathing facilities in some families.