Current asthma contributes as much as smoking to chronic bronchitis in middle age: a prospective population-based study
Received 8 January 2016
Accepted for publication 8 March 2016
Published 16 August 2016 Volume 2016:11(1) Pages 1911—1920
Checked for plagiarism Yes
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Peer reviewers approved by Dr Charles Downs
Peer reviewer comments 2
Editor who approved publication: Dr Richard Russell
Shyamali C Dharmage,1 Jennifer L Perret,1,2, John A Burgess,1 Caroline J Lodge,1 David P Johns,3 Paul S Thomas,4 Graham G Giles,1,5 John L Hopper,1,6 Michael J Abramson,7,8 E Haydn Walters,3,9, Melanie C Matheson1
1Allergy and Lung Health Unit, Center for Epidemiology and Biostatistics, The University of Melbourne, 2Institute for Breathing and Sleep (IBAS), Melbourne, VIC, 3“Breathe Well” Center of Research Excellence for Chronic Respiratory Disease and Lung Ageing, School of Medicine, University of Tasmania, Hobart, TAS, 4Inflammation and Infection Research, Faculty of Medicine, University of New South Wales, Sydney, NSW, 5Cancer Epidemiology Center, Cancer Council Victoria, Melbourne, VIC, Australia; 6Department of Public Health, Seoul National University, Seoul, South Korea; 7Allergy, Immunology and Respiratory Medicine, The Alfred Hospital, Melbourne, 8School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, 9School of Medicine, University of Tasmania, Hobart, TAS, Australia
Background and objective: Personal smoking is widely regarded to be the primary cause of chronic bronchitis (CB) in adults, but with limited knowledge of contributions by other factors, including current asthma. We aimed to estimate the independent and relative contributions to adult CB from other potential influences spanning childhood to middle age.
Methods: The population-based Tasmanian Longitudinal Health Study cohort, people born in 1961, completed respiratory questionnaires and spirometry in 1968 (n=8,583). Thirty-seven years later, in 2004, two-thirds responded to a detailed postal survey (n=5,729), from which the presence of CB was established in middle age. A subsample (n=1,389) underwent postbronchodilator spirometry between 2006 and 2008 for the assessment of chronic airflow limitation, from which nonobstructive and obstructive CB were defined. Multivariable and multinomial logistic regression models were used to estimate relevant associations.
Results: The prevalence of CB in middle age was 6.1% (95% confidence interval [CI]: 5.5, 6.8). Current asthma and/or wheezy breathing in middle age was independently associated with adult CB (odds ratio [OR]: 6.2 [95% CI: 4.6, 8.4]), and this estimate was significantly higher than for current smokers of at least 20 pack-years (OR: 3.0 [95% CI: 2.1, 4.3]). Current asthma and smoking in middle age were similarly associated with obstructive CB, in contrast to the association between allergy and nonobstructive CB. Childhood predictors included allergic history (OR: 1.3 [95% CI: 1.1, 1.7]), current asthma (OR: 1.8 [95% CI: 1.3, 2.7]), “episodic” childhood asthma (OR: 2.3 [95% CI: 1.4, 3.9]), and parental bronchitis symptoms (OR: 2.5 [95% CI: 1.6, 4.1]).
Conclusion: The strong independent association between current asthma and CB in middle age suggests that this condition may be even more influential than personal smoking in a general population. The independent associations of childhood allergy and asthma, though not childhood bronchitis, as clinical predictors of adult CB raise the possibility of some of this burden having originated in childhood.
Keywords: nonobstructive chronic bronchitis, obstructive chronic bronchitis, current asthma, personal smoking, allergy history
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