Prevalence and risk factors of airflow obstruction in an elderly Chinese population

¹ Dept of Medicine and Therapeutics, The Chinese University of Hong Kong
² Dept of Community and Family Medicine, The Chinese University of Hong Kong
³ Nethersole School of Nursing, The Chinese University of Hong Kong

^* To whom correspondence should be addressed. E-mail: dschui{at}cuhk.edu.hk.

	Abstract

It is common practice to adopt FEV₁/FVC ratio of <70% as evidence of airflow obstruction. As FEV₁/FVC ratio falls with age, the lower limit of normal (LLN), defined as the bottom 5% in a health reference population, of FEV₁/FVC ratio has been suggested as a better index to reduce over-diagnosis of COPD, particularly in the elderly. There are however no large scale studies that focus on the diagnosis of COPD in the elderly based on these definitions.

This is a prospective epidemiological study involving 1,149 elderly subjects aged 60 years in the community. Detailed questionnaire, pre- and post-bronchodilator spirometry were performed.

Altogether 1,008 subjects [mean age 74.2(SD6.4)years, 271 males) completed satisfactory spirometry testing. Airflow obstruction was present in 25.9% and 12.4% as defined by the post-bronchodilator FEV₁/FVC <70% and the LLN of FEV₁/FVC respectively. At least moderate COPD was found in 14.0% and 8.5% according to the post-bronchodilator FEV₁/FVC <70% and LLN of FEV₁/FVC respectively.

In this elderly Chinese population (mostly women, with low education level and previous exposure to biomass during formative years), the prevalence of COPD varied markedly depending on definitions adopted. Longitudinal studies are needed to determine the precise definitions of COPD.

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