Level 1 [likely reliable] evidence
The American Academy of Dermatology recommends the direct application of emollients to the skin in patients with atopic dermatitis. However, the addition of oils, emollients, or other additives to bath water is not recommended due to insufficient evidence regarding their efficacy.
In the recent pragmatic multicenter BATHE trial, 483 children aged 1 to 11 years who bathed at least once weekly were randomly assigned to emollient bath additives vs no bath additives for 52 weeks. Participating clinics were encouraged to prescribe Oilatum (63% light liquid paraffin), Aveeno® bath oil, or Balneum (85% soya oil). All patients received advice on the use of emollients as a soap substitute; the continued use of regular emollients directly applied to the skin; and, when necessary, topical corticosteroids. The primary outcome was the mean score over 16 weeks on the caregiver-reported Patient Oriented Eczema Measure (POEM). The POEM scale ranges from 0 to 28 points, with higher scores indicating more severe symptoms and with 3 points considered to be the minimal clinically important difference. At baseline, the family caregiver’s belief in the efficacy of emollient bath additives was assessed using a scale with a range of 1 to 9 points, with 1 indicating no efficacy at all.
At baseline, the means of both the POEM score (9.5 points in the bath-additive group vs 10.1 points in the no-bath-additive group) and “belief in efficacy” score (5.1 points vs 4.8 points) were similar between the groups. Emollient bath additives were used for every bath in 74% of patients in the bath-additive group and never used in 87% of patients in the no-bath-additive group. There was no significant difference in mean POEM score over 16 weeks (7.5 points vs 8.4 points, adjusted mean difference 0.41 points lower; 95% CI, -1.1 to 0.27 points). There were also no significant differences in mean POEM score over 52 weeks, disease-specific and generic quality of life at either 16 or 52 weeks, or number of prescriptions for topical corticosteroids or calcineurin inhibitors.
The BATHE trial demonstrated that adding emollients to bath water did not reduce symptoms of atopic dermatitis in children who continued with their usual treatments. The authors note that it was not possible to make a convincing placebo emollient. The lack of blinding raises the concern that knowledge of the intervention could influence the outcome scores. Indeed, a subgroup analysis of caregivers who had a high belief in the efficacy of emollient bath additives demonstrated a significant difference in symptom scores favoring the use of bath additives. Concerns related to this finding, however, are mitigated by the similar baseline scores on the “belief in efficacy scale” between the 2 groups.
In summary, the findings of the BATHE trial do not support the use of emollient bath additives to improve symptoms in children with atopic dermatitis.
Alan Ehrlich, MD, is a deputy editor for DynaMed, Ipswich, Massachusetts, and assistant clinical professor in family medicine, University of Massachusetts Medical School, Worcester.
DynaMed is a database that provides evidence-based information on more than 3000 clinical topics and is updated daily through systematic surveillance covering more than 500 journals.
Emollient bath additives for the treatment of childhood eczema (BATHE): multicentre pragmatic parallel group randomised controlled trial of clinical and cost effectiveness. BMJ 2018;361:k1332.