Causes of chronic lung disease in middle aged and older adults

A/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 a major public health problem, particularly in adults over the age of 45. COPD arises from an interaction between genetic susceptibility and environmental agents. The best known environmental risk factor is cigarette smoking. Whilst dusty occupations have long been associated with COPD, the role of other occupational exposures to gases, vapours and fumes is not clear. Indoor exposures to products of combustion particularly from unvented gas appliances may also be important.

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.

We are in the data collection stage of this project.

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 (In press)