A multicentre randomized controlled trial of ion-exchange water softeners for the treatment of eczema in children: protocol for the Softened Water Eczema Trial (SWET) (ISRCTN: 71423189)

Background: There is epidemiological evidence linking increased water hardness with increased eczema prevalence. A number of plausible mechanisms can be forwarded to suggest why hard water could exacerbate eczema. The most likely explanation is increased soap usage in hard water areas, the deposits of which can cause skin irritation in individuals with eczema.

Objectives: To assess the cost and cost‐effectiveness of ion‐exchange water softeners for the treatment of eczema in children.

Patients/Methods: Three hundred and ten children aged 6 months to 16 years, with moderate to severe eczema. The children must live in hard water areas (≥ 200 mg L−1 of calcium carbonate) and have a home that is suitable for the installation of a water softener. This is a single‐blind, parallel‐group, randomized controlled trial of 12 weeks duration followed by a 4‐week cross‐over period.

Results/Analysis Plan: Primary outcome: difference in the mean change in disease severity (Six Area, Six Sign Atopic Dermatitis score) at 12 weeks compared with baseline. Secondary outcomes: (i) proportion of time spent moving during the night; (ii) self‐reported global changes in eczema severity; (iii) amount of topical treatment used; (iv) Patient Oriented Eczema Measure; (v) number of totally controlled and well controlled weeks; (vi) impact on health‐related quality of life for the child (EQ‐5D) and the family (Dermatitis Family Impact questionnaire); and (vii) cost‐effectiveness. It is planned that recruitment will be completed by the end of 2008 and results will be available towards the end of 2009.