title: Incidence of hand eczema in a population-based twin cohort: genetic and environmental risk factors.
abstract: BACKGROUND
  Population-based studies on the incidence of hand eczema are sparse.
  
  
  OBJECTIVE
  The aim of this prospective follow-up study was to determine the incidence rate of hand eczema in a population-based twin cohort. Secondly, the role of genetic factors and other potential risk factors for hand eczema was investigated.
  
  
  METHODS
  A questionnaire on self-reported hand eczema was answered by 5610 and 4128 twin individuals in 1996 and 2005, respectively. Data were analysed in a Poisson regression analysis.
  
  
  RESULTS
  The crude incidence rate was 8.8 cases per 1000 person-years (95% confidence interval, [CI] 7.7-9.9). Incidence rate ratios (IRRs) dependent on the co-twin's hand eczema status revealed a significant, doubled risk for monozygotic twin individuals with a co-twin affected by hand eczema, compared with dizygotic twin individuals with a co-twin affected by hand eczema (IRR 2.4, 95% CI 1.4-4.1). Also, significantly increased IRRs were found for positive patch test, atopic dermatitis, and wet work.
  
  
  CONCLUSIONS
  Hand eczema is still a frequent disease and genetic factors are confirmed important risk factors. Positive patch test, atopic dermatitis and wet work were associated with an increased risk, whereas no association with age, sex, smoking or alcohol was found.
authors.affiliation: National Allergy Research Centre, Gentofte Hospital, University of Copenhagen, Ledreborg Allé 40, 1., 2820 Gentofte, Denmark. anne.lerbaek@dadlnwt.dk
authors.forename: A
authors.initials: A
authors.lastname: Lerbaek
authors.forename: K O
authors.initials: KO
authors.lastname: Kyvik
authors.forename: H
authors.initials: H
authors.lastname: Ravn
authors.forename: T
authors.initials: T
authors.lastname: Menné
authors.forename: T
authors.initials: T
authors.lastname: Agner
mesh_terms: D000328:Adult; D017677:Age Distribution; D003718:Denmark / Q000453:epidemiology; D003877:Dermatitis, Contact / Q000453:epidemiology*; D004812:Epidemiologic Methods; D005260:Female; D006229:Hand Dermatoses / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017678:Sex Distribution; D014427:Twins