title: The role of outdoor fungi on asthma hospital admissions in children and adolescents: A 5-year time stratified case-crossover analysis.
abstract: Some fungal spores can trigger asthma exacerbation but knowledge of which outdoor fungal spores contribute to asthma hospitalisation is limited.
  
  
  
  To examine the role of outdoor fungal spores in child and adolescent asthma hospitalisations.
  
  
  
  We conducted a bi-directional time-stratified case-crossover study of child and adolescent asthma hospitalisations over 5 years. Conditional logistic regression assessed the role of 20 fungi taxa (Same day [L0] and lagged [L1-3]) adjusted for maximum temperature, humidity and grass pollen. Strata specific effects were explored if there was evidence of effect modification by age, sex, air pollutants or grass pollen. Non-linear effects examined with Generalized Additive Models.
  
  
  
  Of 2098 children hospitalised for asthma, 60% were boys; mean age was 5.5±3.7 years. Fungal spore counts peaked during warm months. Regression models found weak associations with Coprinus [L0,L1: OR=1.03, 1.01-1.06], Periconia [L0: OR=1.03, 1.001-1.07] and Chaetomium [L2: OR=1.08, 1.0-1.2]. Sex appeared to act as an effect modifier with girls having stronger associations with Cladosporium, Coprinus and total fungi. Older adolescent (14-18 years) hospitalisation was significantly associated with Coprinus and Ustilago/smuts. Air pollutants and grass pollen did not appear to act as effect modifiers. Non-linearity was not detected.
  
  
  
  There may be associations between some outdoor fungal spores and asthma hospitalisations. Further research needed to explore whether these findings can be replicated; and examine whether fungal sensitisation and/or human rhinovirus infections are associated with stronger effects. If findings are replicated, then the need to develop predictive models for fungal spore distribution and levels may become more important.
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia. Electronic address: rtham@student.unimelb.edu.au.
authors.forename: Rachel
authors.initials: R
authors.lastname: Tham
authors.affiliation: Western Sydney University, Department of Medicine, Immunology and Allergy, Campbelltown Hospital, Campbelltown, New South Wales, Australia. Electronic address: connie.katelaris@sswahs.nsw.gov.au.
authors.forename: Constance H
authors.initials: CH
authors.lastname: Katelaris
authors.affiliation: School of Public Health, College of Science Health and Engineering, La Trobe University, Bundoora, Victoria, Australia. Electronic address: vicendese.don@gmail.com.
authors.forename: Don
authors.initials: D
authors.lastname: Vicendese
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia. Electronic address: s.dharmage@unimelb.edu.au.
authors.forename: Shyamali C
authors.initials: SC
authors.lastname: Dharmage
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia. Electronic address: lowea@unimelb.edu.au.
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Lowe
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia. Electronic address: gbowatte@gmail.com.
authors.forename: Gayan
authors.initials: G
authors.lastname: Bowatte
authors.affiliation: School of Life and Environmental Sciences, Deakin University, Geelong, Victoria, Australia. Electronic address: philip.taylor@deakin.edu.au.
authors.forename: Philip
authors.initials: P
authors.lastname: Taylor
authors.affiliation: Western Sydney University, Department of Medicine, Immunology and Allergy, Campbelltown Hospital, Campbelltown, New South Wales, Australia. Electronic address: Pamela.Burton@sswahs.nsw.gov.au.
authors.forename: Pamela
authors.initials: P
authors.lastname: Burton
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia. Electronic address: michael.abramson@monash.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Abramson
authors.affiliation: School of Public Health, College of Science Health and Engineering, La Trobe University, Bundoora, Victoria, Australia. Electronic address: B.Erbas@latrobe.edu.au.
authors.forename: Bircan
authors.initials: B
authors.lastname: Erbas
mesh_terms: D000293:Adolescent; D000391:Air Microbiology; D000397:Air Pollution; D001249:Asthma / Q000453:epidemiology* / Q000382:microbiology*; D001315:Australia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D018592:Cross-Over Studies; D004781:Environmental Exposure; D005260:Female; D005658:Fungi / Q000472:pathogenicity*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D011058:Pollen; D013172:Spores, Fungal
keywords: Adolescent; Asthma hospitalisations; Case cross-over; Child; Outdoor fungi