Clinical Epidemiology Unit - Alfred

Causes of chronic lung disease in middle aged and older adults

Professor Michael Abramson
A /Professor Malcolm Sim
Professor Haydn Walters

Funded by:
NH&MRC 2000 - 2002
Victorian Tuberculosis & Lung Foundation - 2001
Windermere Foundation - 2001

Chronic Obstructive Pulmonary Disease (COPD) is common in middle aged and older people.  We found that respiratory symptoms such as wheezing, cough with phlegm, and shortness of breath hurrying or walking uphill were respectively reported by 20.5%, 12.5% and 27.2% of people aged 45 to 70 years.  About one out of every 19 people in this age group had objective evidence of COPD on lung function tests.  However more than 40% of subjects with COPD had not been diagnosed by their doctors and less than half had ever been prescribed medication for their breathing.  Thus we conclude that most patients with COPD are being undertreated and call for improvements in diagnosis, monitoring and referral systems.

The major known cause of COPD is cigarette smoking.  This research project found for the first time that occupational exposures to biological dusts (such as bacteria, moulds, pollens and textile fibres) were associated with almost a 3 fold increase in the risk of COPD.  This risk was higher in women than men.  We conclude that workplace exposures to biological dusts of groups such as nurses, health workers, food and textile workers and cleaners need to be reduced.  However we were unable to identify any genes that significantly increased the risk of COPD and this area requires further research.

Methods: A random sample of 7,005 adults aged between 45-69 years was drawn from the electoral rolls of the inner eastern suburbs of Melbourne. A postal survey was conducted using the validated ECRHS respiratory screening questionnaire with additional questions on chronic bronchitis and emphysema. Participants were asked to return the survey by reply mail. Non-responders were sent a reminder postcard after 2 weeks, a replacement questionnaire after 4 weeks and then contacted by telephone.

Results: Completed questionnaires were returned by 4,906 (70.0%) participants of whom 46.5% were male. The commonest symptoms were exertional dyspnoea and wheezing reported by 27.2% and 20.5% of respondents respectively. Asthma was reported by 15.0% and 6.7% reported an attack in the past 12 months. Chronic bronchitis was reported by 12.0% and emphysema by 1.2%. Males were significantly more likely to report cough and sputum, whereas females were more likely to report asthma. The prevalence of exertional dyspnoea, cough and sputum, emphysema and heart disease increased with age. Chronic bronchitis, emphysema and most respiratory symptoms were associated with smoking.

Conclusions: Although asthma is less prevalent than among young adults, self reported chronic bronchitis or emphysema (COPD) affect one in eight middle aged and older adults. Differences between men and women are largely explained by differences in past smoking. These findings require confirmation with objective tests of lung function.  

A random sample of the respondents are now being invited to the laboratory to complete a detailed respiratory questionnaire, food frequency questionnaire, methacholine challenge test to measure bronchial hyperreactivity, transfer factor by the single breath carbon monoxide method, skin prick tests for atopy and have blood taken for measurement of plasma fatty acid levels.

Publications:

Abramson M, Matheson M, Wharton C, Sim M, Walters EH. Prevalence of respiratory symptoms related to chronic obstructive pulmonary disease and asthma amongst middle aged and older adults. Respirology 2002

Abramson M.  Respiratory symptoms and lung function in older people with asthma or COPD.  Med J Aust 2005;183 (1, Suppl):S23-25

Matheson MC, Benke G, Raven J, Sim MR, Kromhout H, Vermeulen R, Johns DP, Walters EH, Abramson MJ.  Biological dust exposure in the workplace is a risk factor for Chronic Obstructive Pulmonary Disease.  Thorax 2005;60(8):645-651

Matheson MC, Abeysena C, Raven JM, Skoric B, Johns DP, Abramson MJ, Walters EH.  How have we been managing chronic obstructive pulmonary disease in Australia?  Int Med J 2006;36(2):92-99

Matheson MC, Raven J, Walters EH, Abramson MJ, Ellis JA.  Association of TNF-a, CXCR2 and IL8 Polymorphisms and Airway Disease.  J Hum Genet 2006;51(3):196-203

Matheson MC, Ellis JA, Raven J, Johns DP, Walters EH, Abramson MJ.  b_2 -adrenergic receptor haplotypes are associated with asthma and COPD in an adult population.  J Human Genetics 2006;51(11): 943-951

Matheson MC, Raven J, Walters EH, Abramson MJ, Ellis JA.  Microsomal Epoxide Hydrolase is not associated with COPD in a community-based sample of middle aged and older adults.  Human Biology 2006;78(6):705-717

Matheson M, Raven J, Johns DP, Abramson M, Walters EH.  Associations between reduced diffusion capacity and airflow obstruction in community based subjects.  Resp Med 2007;101:1730-1737