Ion-Exchange Water Softener Use and Eczema

Abstract

Question: Does water softener use improve eczema? Design: Observer-blind, parallel group, randomized, active-controlled trial. Setting: Participants were recruited from primary care, secondary care referral centers, and the community in 8 centers in the United Kingdom. Patients: Children aged 6 months to 16 years with moderate to severe eczema (baseline Six Area, Six Sign Atopic Dermatitis [SASSAD] severity score 10) living in a home with hard water ( 200 mg/L calcium carbonate). Intervention: Children were randomized to receive either ion-exchange water softeners installed in their homes plus usual eczema care or usual eczema care alone. Randomization was stratified by disease severity (baseline SASSAD score 20 or 20) and recruiting center on a 1:1 basis. Outcome Measures: The primary outcome was the difference in the mean change in disease severity (SASSAD score) between the intervention group and the usual care group at 12 weeks. The SASSAD score was measured by research nurses who were blinded to treatment allocation and did not require input from the children or the family. Secondary outcomes included the difference in the proportion of time spent moving during the night, measured with accelerometers worn by the children, and the difference in the amount of topical medications (corticosteroids and/or calcineurin inhibitors) used during the 12-week study period, measured by weighing the medication for each child. Differences between groups in patient-reported measures of disease severity, disease impact, and health-related quality of life were also assessed. Results: Of the 1215 patients assessed for eligibility, 336 patients were randomized, with 170 allocated to the intervention group and 166 allocated to the usual care group. In the intervention group, water softeners were installed for an average of 74 days. In the intention-to-treat analysis, the SASSAD scores of the intervention group improved by 20% and those of the usual care group improved by 22% at 12 weeks. The difference in the mean change of disease severity between the 2 groups was 0.66 (95% CI, –1.37 to 2.69; P=.53). The lack of a significant difference remained in the per protocol analysis (mean difference, 1.87; 95% CI, –0.07 to 4.47; P=.16). There also were no significant differences in the objective secondary outcomes (time spent moving during the night and amount of topical medications used). There were small but statistically significant differences favoring the intervention in 3 of the 4 unblinded patient assessed outcomes. Conclusions: Water softeners are not an effective addition to usual care for the treatment of moderate to severe eczema in children. The small benefits in some of the unblinded subjective outcomes were likely a result of response bias.