Atopic dermatitis and skin disease
Pet exposure and risk of atopic dermatitis at the pediatric age: A meta-analysis of birth cohort studies

https://doi.org/10.1016/j.jaci.2013.04.009Get rights and content

Background

Findings on pet exposure and the risk of atopic dermatitis (AD) in children are inconsistent.

Objective

With the aim to summarize the results of exposure to different pets on AD, we undertook a meta-analysis of epidemiologic studies on this issue.

Methods

In August 2012, we conducted a systematic literature search in Medline and Embase. We included analytic studies considering exposure to dogs, cats, other pets, or pets overall during pregnancy, infancy, and/or childhood, with AD assessment performed during infancy or childhood. We calculated summary relative risks and 95% CIs using both fixed- and random-effects models. We computed summary estimates across selected subgroups.

Results

Twenty-six publications from 21 birth cohort studies were used in the meta-analyses. The pooled relative risks of AD for exposure versus no exposure were 0.72 (95% CI, 0.61-0.85; I2 = 46%; results based on 15 studies) for exposure to dogs, 0.94 (95% CI, 0.76-1.16; I2 = 54%; results based on 13 studies) for exposure to cats, and 0.75 (95% CI, 0.67-0.85; I2 = 54%; results based on 11 studies) for exposure to pets overall. No heterogeneity emerged across the subgroups examined, except for geographic area.

Conclusion

This meta-analysis reported a favorable effect of exposure to dogs and pets on the risk of AD in infants or children, whereas no association emerged with exposure to cats.

Section snippets

Methods

This systematic review was conducted according to the Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines for reporting meta-analysis of observational studies.28 We registered this review in the International Prospective Register of Systematic Reviews (PROSPERO, registration no. CRD42012002908), describing in advance the aims and methods of our investigation.29

In August 2012 we performed a systematic literature search of the Medline and Embase databases for cohort and

Results

Fig 1 shows the selection process of publications in a flowchart. Overall, 307 publications were identified in PubMed and 93 in Embase. By examining the title and abstract, approximately three fourths of the articles were excluded as irrelevant (eg, studies of food allergies, atopic or dermatologic diseases other than AD, sensitization to several allergens, dust mite exposures, and treatment/prognosis and review articles). Furthermore, 20 of the retained publications were present in both

Discussion

This meta-analysis of birth cohort studies reported an approximately 25% decreased risk of AD for children who experienced exposure to dogs and pets overall, whereas no association emerged with cat exposure. Moderate heterogeneity between studies was reported, and thus results should be considered with caution because global estimates could be influenced by confounding factors not considered in the analyses. There was no evidence of publication bias, notwithstanding the fact that all the

References (67)

  • S.M. Tariq et al.

    The prevalence of and risk factors for atopy in early childhood: a whole population birth cohort study

    J Allergy Clin Immunol

    (1998)
  • B. Bjorksten et al.

    Allergy development and the intestinal microflora during the first year of life

    J Allergy Clin Immunol

    (2001)
  • C. Svanes et al.

    Pet-keeping in childhood and adult asthma and hay fever: European community respiratory health survey

    J Allergy Clin Immunol

    (2003)
  • J.F. Bach

    The effect of infections on susceptibility to autoimmune and allergic diseases

    N Engl J Med

    (2002)
  • D.P. Strachan

    Hay fever, hygiene, and household size

    BMJ

    (1989)
  • W. Eder et al.

    Hygiene hypothesis and endotoxin: what is the evidence?

    Curr Opin Allergy Clin Immunol

    (2004)
  • C.J. Lodge et al.

    Pets at birth do not increase allergic disease in at-risk children

    Clin Exp Allergy

    (2012)
  • P. Nafstad et al.

    Exposure to pets and atopy-related diseases in the first 4 years of life

    Allergy

    (2001)
  • U. Sandini et al.

    Protective and risk factors for allergic diseases in high-risk children at the ages of two and five years

    Int Arch Allergy Immunol

    (2011)
  • B. Brunekreef et al.

    Exposure to cats and dogs, and symptoms of asthma, rhinoconjunctivitis, and eczema

    Epidemiology

    (2012)
  • O.S. Von Ehrenstein et al.

    Reduced risk of hay fever and asthma among children of farmers

    Clin Exp Allergy

    (2000)
  • M. Waser et al.

    Exposure to pets, and the association with hay fever, asthma, and atopic sensitization in rural children

    Allergy

    (2005)
  • D. Oberle et al.

    Childhood asthma and continuous exposure to cats since the first year of life with cats allowed in the child's bedroom

    Allergy

    (2003)
  • E. von Mutius et al.

    Exposure to endotoxin or other bacterial components might protect against the development of atopy

    Clin Exp Allergy

    (2000)
  • B. Takkouche et al.

    Exposure to furry pets and the risk of asthma and allergic rhinitis: a meta-analysis

    Allergy

    (2008)
  • C.M. Chen et al.

    Re: Exposure to furry pets and the risk of asthma and allergic rhinitis: a meta-analysis

    Allergy

    (2009)
  • K.C. Lodrup Carlsen et al.

    Does pet ownership in infancy lead to asthma or allergy at school age? Pooled analysis of individual participant data from 11 European birth cohorts

    PLoS One

    (2012)
  • C. Flohr et al.

    Atopic dermatitis and the hygiene hypothesis revisited

    Curr Probl Dermatol

    (2011)
  • S.M. Langan et al.

    The role of furry pets in eczema: a systematic review

    Arch Dermatol

    (2007)
  • B. Alm et al.

    Early introduction of fish decreases the risk of eczema in infants

    Arch Dis Child

    (2009)
  • C. Almqvist et al.

    Effects of early cat or dog ownership on sensitisation and asthma in a high-risk cohort without disease-related modification of exposure

    Paediatr Perinat Epidemiol

    (2010)
  • S. Dom et al.

    Pre- and post-natal exposure to antibiotics and the development of eczema, recurrent wheezing and atopic sensitization in children up to the age of 4 years

    Clin Exp Allergy

    (2010)
  • E. Eller et al.

    Meta-analysis of determinants for pet ownership in 12 European birth cohorts on asthma and allergies: a GA2LEN initiative

    Allergy

    (2008)
  • Cited by (0)

    Supported by the European Research Council, grant agreement no. 250290.

    Disclosure of potential conflict of interest: The authors have been supported by one or more grants from the European Research Council.

    View full text