title: Assessment of pet exposure by self-report in epidemiological studies of allergy and asthma: a systematic review.
abstract: OBJECTIVE
  In epidemiological studies that aim to investigate the relationship between pet exposure and allergy/asthma, pet exposure is often ascertained by means of a questionnaire, but it is unclear which questionnaire items are used. The objective of this study was to systematically review self-reported pet exposure assessment in questionnaires used in epidemiological studies which explore the associations between pets and allergy/asthma.
  
  
  METHODS
  A systematic literature search was conducted in PubMed and papers were selected according to pre-specified eligibility criteria. The pet exposure questions used were classified within a framework including direct pet contact, indirect pet contact (e.g. through carers or grandparents) and avoidance behaviour. Authors were contacted when the questions used were not reported in detail.
  
  
  RESULTS
  Ninety-six full text papers were systematically reviewed. All studies assessed direct pet contact, but less than half (45%) explicitly assessed whether pets were allowed indoors. The vast majority of studies assessed both pet exposures during the first year of life and after the first year of life. The minority (13%) assessed whether pet(s) were kept at places regularly visited by the child and pet exposure in utero (15%). Even fewer studies assessed indirect contact to pets (n = 8) and avoidance behaviour (n = 10).
  
  
  CONCLUSIONS
  In epidemiological studies, the ascertainment of pet exposure through questionnaires appears to vary greatly. This variation might partly explain the inconsistent and contradictory results of the effects of pet exposure on the development of allergy and asthma.
authors.affiliation: a Division of Public Health and Primary Care , Brighton and Sussex Medical School , Brighton , UK and.|b Department of Medical Sociology , Institute of Epidemiology and Preventive Medicine, University of Regensburg , Regensburg , Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Apfelbacher
authors.affiliation: a Division of Public Health and Primary Care , Brighton and Sussex Medical School , Brighton , UK and.
authors.forename: Edward
authors.initials: E
authors.lastname: Frew
authors.affiliation: a Division of Public Health and Primary Care , Brighton and Sussex Medical School , Brighton , UK and.
authors.forename: Ally
authors.initials: A
authors.lastname: Xiang
authors.affiliation: a Division of Public Health and Primary Care , Brighton and Sussex Medical School , Brighton , UK and.
authors.forename: Alex
authors.initials: A
authors.lastname: Apfel
authors.affiliation: a Division of Public Health and Primary Care , Brighton and Sussex Medical School , Brighton , UK and.
authors.forename: Helen
authors.initials: H
authors.lastname: Smith
mesh_terms: D000818:Animals; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology*; D016021:Epidemiologic Studies; D006801:Humans; D006967:Hypersensitivity / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology*; D057805:Pets / Q000276:immunology; D057566:Self Report
keywords: Allergy; asthma; epidemiology; exposure assessment; pet exposure; questionnaire