King's College London

Research portal

Longitudinal analysis of the effect of water hardness on atopic eczema: evidence for gene-environment interaction

Research output: Contribution to journalArticle

Z K Jabbar-Lopez, J Craven, K Logan, D Greenblatt, T Marrs, S Radulovic, W H I McLean, G Lack, D P Strachan, M R Perkin, J L Peacock, C Flohr

Original languageEnglish
JournalThe British journal of dermatology
Early online date10 Oct 2019
Publication statusE-pub ahead of print - 10 Oct 2019

Bibliographical note

© 2019 British Association of Dermatologists.

King's Authors


Background: Several studies have identified an association between water hardness and atopic eczema (AE); however, there is a paucity of longitudinal data in early life. Objectives: To examine whether water hardness is associated with an increased risk of AE and skin barrier dysfunction in infants and to assess effect modification by filaggrin (FLG) loss-of-function variants. Methods: We performed a longitudinal analysis of data from infants in the Enquiring About Tolerance (EAT) study, who were enrolled at 3 months and followed up until 36 months of age. Results: Of 1303 infants enrolled in the EAT study, 91·3% (n = 1189) attended the final clinic visit and 94·0% (n = 1225) of participants’ families completed the 36-month questionnaire. In total, 761 (58·4%) developed AE by 36 months. There was no overall association between exposure to harder (> 257 mg L −1 CaCO 3) vs. softer (≤ 257 mg L −1 CaCO 3) water: adjusted hazard ratio (HR) 1·07, 95% confidence interval (CI) 0·92–1·24. However, there was an increased incidence of AE in infants with FLG mutations exposed to hard water (adjusted HR 2·72, 95% CI 2·03–3·66), and statistically significant interactions between hard water plus FLG and both risk of AE (HR 1·80, 95% CI 1·17–2·78) and transepidermal water loss (0·0081 g m −2 h −1 per mg L −1 CaCO 3, 95% CI 0·00028–0·016). Conclusions: There is evidence of an interaction between water hardness and FLG mutations in the development of infantile AE.

View graph of relations

© 2018 King's College London | Strand | London WC2R 2LS | England | United Kingdom | Tel +44 (0)20 7836 5454