A multicentre randomised controlled trial and economic evaluation of ion-exchange water softeners for the treatment of eczema in children: the Softened Water Eczema Trial (SWET).

摘要

OBJECTIVES: To determine whether installation of an ion-exchange water softener in the home could improve atopic eczema in children and, if so, to establish its likely cost and cost-effectiveness. DESIGN: An observer-blind, parallel-group randomised controlled trial of 12 weeks duration followed by a 4-week observational period. Eczema was assessed by research nurses blinded to intervention at baseline, 4 weeks, 12 weeks and 16 weeks. The primary outcome was analysed as intent-to-treat, using the randomised allocation rather than actual treatment received. A secondary per-protocol analysis excluded participants who failed to receive their allocated treatment and who were deemed to be protocol violators. SETTING: Secondary and primary care referral centres in England (UK) serving a variety of ethnic and social groups and including children living in both urban and periurban homes. PARTICIPANTS: Three hundred and thirty-six children (aged 6 months to 16 years) with moderate/severe atopic eczema, living in homes in England supplied by hard water (>/= 200 mg/l calcium carbonate). INTERVENTIONS: Participants were randomised to either installation of an ion-exchange water softener plus usual eczema care (group A) for 12 weeks or usual eczema care alone (group B) for 12 weeks. This was followed by a 4-week observational period, during which water softeners were switched off/removed from group A homes and installed in group B homes. Standard procedure was to soften all water in the home, but to provide mains (hard) water at a faucet-style tap in the kitchen for drinking and cooking. Participants were therefore exposed to softened water for bathing and washing of clothes, but continued to drink mains (hard) water. Usual care was defined as any treatment that the child was currently using in order to control his or her eczema. New treatment regimens used during the trial period were documented. MAIN OUTCOME MEASURES: Primary outcome was the difference between group A and group B in mean change in disease severity at 12 weeks compared with baseline, as measured using the Six Area, Six Sign Atopic Dermatitis (SASSAD) score. This is an objective severity scale completed by blinded observers (research nurses) unaware of the allocated intervention. Secondary outcomes included use of topical medications, night-time movement, patient-reported eczema severity and a number of quality of life measures. A planned subgroup analysis was conducted, based on participants with at least one mutation in the gene encoding filaggrin (a protein in the skin thought to be important for normal skin barrier function).