Clinical and functional differences between early-onset and late-onset adult asthma: a population-based Tasmanian Longitudinal Health Study.
BACKGROUND
Differences between early-onset and late-onset adult asthma have not been comprehensively described using prospective data.


OBJECTIVE
To characterise the differences between early-onset and late-onset asthma in a longitudinal cohort study.


METHODS
The Tasmanian Longitudinal Health Study (TAHS) is a population-based cohort. Respiratory histories and spirometry were first performed in 1968 when participants were aged 7 (n=8583). The cohort was traced and resurveyed from 2002 to 2005 (n=5729 responses) and a sample, enriched for asthma and bronchitis participated in a clinical study when aged 44 (n=1389).


RESULTS
Of the entire TAHS cohort, 7.7% (95% CI 6.6% to 9.0%) had early-onset and 7.8% (95% CI 6.4% to 9.4%) late-onset asthma. Atopy and family history were more common in early-onset asthma while female gender, current smoking and low socioeconomic status were more common in late-onset asthma. The impact on lung function of early-onset asthma was significantly greater than for late-onset asthma (mean difference prebronchodilator (BD) FEV1/FVC -2.8% predicted (-5.3 to -0.3); post-BD FEV1FVC -2.6% predicted (-5.0 to -0.1)). However, asthma severity and asthma score did not significantly differ between groups. An interaction between asthma and smoking was identified and found to be associated with greater fixed airflow obstruction in adults with late-onset asthma. This interaction was not evident in adults with early-onset disease.


CONCLUSIONS
Early-onset and late-onset adult asthma are equally prevalent in the middle-aged population. Major phenotypic differences occur with asthma age-of-onset; while both share similar clinical manifestations, the impact on adult lung function of early-onset asthma is greater than for late-onset asthma.
Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania, Australia.
Daniel J
DJ
Tan
Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania, Australia.
E Haydn
EH
Walters
Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia.
Jennifer L
JL
Perret
Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia.
John A
JA
Burgess
Menzies Research Institute, Hobart, Tasmania, Australia.
David P
DP
Johns
Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia Murdoch Children Research Institute, Melbourne, Victoria, Australia.
Adrian J
AJ
Lowe
Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia.
Caroline J
CJ
Lodge
Biostatistics Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia.
Panteha
P
Hayati Rezvan
Biostatistics Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia.
Julie A
JA
Simpson
Department of Medicine, University of Queensland, Brisbane, Queensland, Australia.
Stephen
S
Morrison
Department of Allergy Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Victoria, Australia.
Bruce R
BR
Thompson
Department of Medicine, University of New South Wales, Sydney, New South Wales, Australia.
Paul S
PS
Thomas
Gold Coast Hospital, Southport, Queensland, Australia.
Iain
I
Feather
Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Victoria, Australia.
Graham G
GG
Giles
Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia.
John L
JL
Hopper
Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia.
Michael J
MJ
Abramson
Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia.
Melanie C
MC
Matheson
Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia Murdoch Children Research Institute, Melbourne, Victoria, Australia.
Shyamali C
SC
Dharmage
D000328:Adult; D017668:Age of Onset; D000402:Airway Obstruction / Q000503:physiopathology; D001249:Asthma / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology*; D001993:Bronchodilator Agents / Q000627:therapeutic use; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012129:Respiratory Function Tests; D012307:Risk Factors; D013648:Tasmania / Q000453:epidemiology
D001993:Bronchodilator Agents
Asthma Epidemiology; Respiratory Measurement