BATHE Trial

Design and population. The BATHE trial (Santer et al., BMJ 2018) was a pragmatic, open-label, two-arm superiority RCT in 96 general practices in Wales and western and southern England. It enrolled 483 children aged 1–11 (mean age 5) who met UK diagnostic criteria for Atopic Dermatitis; children with very mild eczema or who bathed less than once a week were excluded. Mean baseline POEM was about 10, i.e. moderate eczema. It was NIHR-funded and asked a practical question: do Emollient Bath Additives, then widely prescribed, add anything to leave-on emollients? BATHE Trial [relates] Atopic Dermatitis

Intervention and primary outcome. The intervention group was prescribed bath additives by their usual clinicians, to use regularly for 12 months. The control group was asked to use none. Both groups continued standard care, including leave-on emollients and Topical Corticosteroids, and all carers got the same written advice on washing, including using leave-on emollient as a soap substitute. The primary outcome was weekly POEM over 16 weeks; secondary outcomes covered eczema over a year, flares needing a GP visit, quality of life, steroid use and cost. POEM [defines] BATHE Trial

Result. Mean POEM over 16 weeks was 7.5 with bath additives and 8.4 without. After adjustment, scores in the no-additive group were only 0.41 points higher (95% CI −0.27 to 1.10), well below the 3-point minimal clinically important difference. There was no difference in any secondary outcome, cost-effectiveness or adverse effects. The authors concluded there was “no evidence of clinical benefit” and that effort should go into leave-on emollients and soap substitutes. BATHE Trial [contradicts] Emollient Bath Additives

Limitations. Families and clinicians were not blinded, and the outcome was parent-reported, which if anything would favour the additives. The authors could not exclude a small benefit in children bathing more than five times a week or aged under 5, but judged any such difference too small to be clinically useful (Medical Xpress 2018). Products varied because they were prescribed in usual practice. BATHE Trial [relates] Bathing Frequency

What it means for toddlers and policy. For a 1–4-year-old, the bath oil is not the treatment; the soak in plain water, a soap substitute, and leave-on emollient straight afterwards are what matter. Oily additives also make the bath slippery for a wriggling toddler. BATHE led NHS England in 2019 to list bath and shower preparations as items not to be routinely prescribed, and NICE CG57 in 2023 to advise not offering emollient bath additives to children under 12. BATHE Trial [supports] NICE CG57 BATHE Trial [supports] Soap Substitutes

Connections

• Emollient Therapy — shows bath additives add no benefit, source: BMJ 2018
• Bathing Frequency — evidence that changing bath water adds little, source: BMJ 2018
• Emollient Bath Additives — the intervention tested; led to NHS England 2019 and NICE 2023 restrictions, source: BMJ 2018; Lincolnshire PACEF
• POEM — primary outcome over 16 weeks, source: Santer 2018
• NICE CG57 — 2023 update: do not offer bath additives to under-12s, source: Lincolnshire PACEF
• Soap Substitutes — standardised washing advice in both arms, source: Santer 2018