title: Multimorbidities of asthma, allergies, and airway illnesses in childhood: Chance or not chance?
abstract: OBJECTIVE
  We investigated patterns of multimorbidities among asthma, allergies, and respiratory illnesses in preschool children. We investigated multimorbidities of lifetime asthma, allergic rhinitis, eczema, food allergy, pneumonia, and ear infections; and multimorbidities of current (in the last year before the survey) wheeze, dry cough, rhinitis, eczema, and common cold during childhood. We further analyzed whether prevalences of these multimorbidities were due to chance.
  
  
  METHODS
  A cross-sectional study was conducted in 72 kindergartens of Shanghai, China. Parents of preschool children were surveyed with a modified ISAAC questionnaire. Observed prevalences (OPs), expected prevalences (EPs), absolute excess comorbidities (AECs), and relative excess comorbidities (RECs) of various combinations of illnesses were calculated to indicate whether the combined illnesses were related.
  
  
  RESULTS
  We analyzed questionnaires for children aged 4-6 years, whose 13,335 questionnaires were the majority of the total 15,266 returned questionnaires (response rate: 85.3%). The studied illnesses were common. For children who had more than three lifetime or current illnesses, OPs tended to be higher than EPs. Most OPs and EPs were higher in boys than in girls, and were higher in children with a family history of atopy (FHA) than in children without FHA. AECs and RECs between boys and girls as well as between children with and without FHA were substantially different.
  
  
  CONCLUSIONS
  Our findings suggest that multimorbidities among childhood asthma, allergies, and respiratory illnesses are likely not random, but rather share etiology. Specific patterns of childhood asthma multimorbidities perhaps differ between boys and girls and between children with and without FHA.
authors.affiliation: a Department of Building Environment and Energy Engineering , School of Environment and Architecture, University of Shanghai for Science and Technology , Shanghai , China.
authors.forename: Wei
authors.identifier: http://orcid.org/0000-0001-9863-4332
authors.initials: W
authors.lastname: Liu
authors.affiliation: a Department of Building Environment and Energy Engineering , School of Environment and Architecture, University of Shanghai for Science and Technology , Shanghai , China.
authors.forename: Chen
authors.initials: C
authors.lastname: Huang
authors.affiliation: a Department of Building Environment and Energy Engineering , School of Environment and Architecture, University of Shanghai for Science and Technology , Shanghai , China.
authors.forename: Xueying
authors.initials: X
authors.lastname: Wang
authors.affiliation: a Department of Building Environment and Energy Engineering , School of Environment and Architecture, University of Shanghai for Science and Technology , Shanghai , China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Cai
authors.affiliation: a Department of Building Environment and Energy Engineering , School of Environment and Architecture, University of Shanghai for Science and Technology , Shanghai , China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Hu
authors.affiliation: a Department of Building Environment and Energy Engineering , School of Environment and Architecture, University of Shanghai for Science and Technology , Shanghai , China.
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Zou
authors.affiliation: b Colts Neck , NJ , USA.
authors.forename: Louise B
authors.initials: LB
authors.lastname: Weschler
authors.affiliation: a Department of Building Environment and Energy Engineering , School of Environment and Architecture, University of Shanghai for Science and Technology , Shanghai , China.
authors.forename: Li
authors.initials: L
authors.lastname: Shen
authors.affiliation: a Department of Building Environment and Energy Engineering , School of Environment and Architecture, University of Shanghai for Science and Technology , Shanghai , China.|c Department of Building Science , Tsinghua University , Beijing , China.
authors.forename: Jan
authors.initials: J
authors.lastname: Sundell
mesh_terms: D001249:Asthma / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003139:Common Cold / Q000453:epidemiology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D004485:Eczema / Q000453:epidemiology; D005260:Female; D005512:Food Hypersensitivity / Q000453:epidemiology; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology*; D008297:Male; D011014:Pneumonia / Q000453:epidemiology; D015995:Prevalence; D012135:Respiratory Sounds / Q000503:physiopathology; D012141:Respiratory Tract Infections / Q000453:epidemiology*; D065631:Rhinitis, Allergic / Q000453:epidemiology
keywords: Asthma; China; children; co-existence; eczema; multimorbidity; rhinitis