title: Eczema and indoor environment: lessons from the International Study of Asthma and Allergies in Childhood (ISAAC) Phase 2.
abstract: BACKGROUND
  Numerous studies have reported a positive association between damp housing conditions and asthma, but little is known about indoor environmental exposures in relation to childhood eczema. We aimed to specifically investigate the effect of indoor mould and dampness on eczema risk in the International Study of Asthma and Allergies in Childhood (ISAAC).
  
  
  METHODS
  ISAAC Phase 2 is a cross-sectional study of 46 051 children aged 8-12 years from 20 countries. Information on demographics, eczema symptoms, and dampness was gathered with parental questionnaires. Children were examined for eczema and underwent skin prick testing. In a stratified subgroup, dust samples were collected to measure house dust mite exposure. Sex, maternal education, parental allergy, pet ownership, maternal smoking, having an older sibling, bedroom sharing, and cooking with fuels were explored as potential confounders or effect modifiers in logistic regression analysis.
  
  
  RESULTS
  Current residential exposure to dampness and mould was significantly associated with flexural eczema in the previous year, with a stronger association seen in non-affluent than in affluent countries (adjusted odds ratio [OR] 1·96, 95% CI 1·62-2·37, vs 1·34, 1·18-1·51). Dampness and mould in the first year of life was also significantly associated with parent-reported eczema ever (1·94, 1·40-2·68, vs 1·43, 1·28-1·60). However, the association with flexural eczema on examination was not significant (0·93, 0·76-1·13). Risk estimates were similar in children positive and negative on skin prick testing, and were not appreciably altered by the effect modifiers, apart from parental allergic disease (parental allergies OR 1·35, 95% CI 1·18-1·54, vs no parental allergies 1·61, 1·37-1·90).
  
  
  CONCLUSIONS
  These data suggest an association between damp housing conditions and childhood eczema symptoms, which may be causal. Further work is needed to elucidate possible mechanisms. Modification to home environment to reduce dampness and mould could be harnessed to improve or even prevent this common and debilitating condition.
  
  
  BACKGROUND
  None.
authors: Department of Allergy, Guy's and St Thomas' NHS Foundation Trust, King's College London, London, UK. Electronic address: teresa.tsakok@kcl.ac.uk.
authors: Teresa
authors: T
authors: Tsakok
authors: Institute of Epidemiology, University of Ulm, Ulm, Germany.
authors: G
authors: G
authors: Weinmayr
authors: Institute of Epidemiology, University of Ulm, Ulm, Germany.
authors: A
authors: A
authors: Jaensch
authors: Division of Community Health Sciences, St George's, University of London, London, UK.
authors: D P
authors: DP
authors: Strachan
authors: Centre for Evidence Based Dermatology, University of Nottingham, Nottingham, UK.
authors: H C
authors: HC
authors: Williams
authors: St John's Institute of Dermatology, Guy's and St Thomas' NHS Foundation Trust, King's College London, London, UK.
authors: C
authors: C
authors: Flohr