Who gets COPD?

The prevalence (the number or proportion of cases present in the population at a given time) of COPD is difficult to determine from routine health surveys. Since COPD is formally defined in terms of an abnormality of lung function, accurately estimating the prevalence of the disease requires clinical testing.

A large international study (Burden of Obstructive Lung Disease (BOLD)) tested the lung function of nearly 10,000 people aged 40 and over. BOLD estimated the overall prevalence of COPD in 12 countries to be 10%. In the one Australian site (in Sydney) included in BOLD the prevalence of COPD was estimated to be 10.8%. Nearly one quarter of those aged 70 and over in the Sydney study were found to have COPD (Buist et al. 2007).
 
New studies using the BOLD methodology have been conducted in five new centres around Australia but a national prevalence estimate based on these results is not yet available.

The 2007–08 Australian Bureau of Statistics (ABS) National Health Survey (NHS) collected data on emphysema and bronchitis using self-reports. There were 252,750 people aged 55 and over in Australia who had one or both of these conditions: that is 5.3% (95% CI 4.5%–6.1%) of the population of that age.

In the 2007–08 NHS, the prevalence of self-reported emphysema and/or bronchitis in Australians 55 and over did not differ significantly between males and females. There is a suggestion in this data that the prevalence of COPD increases with age, although it is not statistically significant.

Despite the limitations of the NHS emphysema and bronchitis estimates as a proxy for COPD prevalence, the data does show some signs that the prevalence of COPD has been declining for some time. The prevalence estimate from the NHS has shown a steady but not statistically significant decline over nearly ten years. The prevalence estimate was 6.8% in 2001 (95% CI 6.0%–7.6%), 6.6% in 2004–05 (95% CI 5.8%–7.3%) and 5.3% in 2007–08 (95% CI 4.5%–6.1%). The conclusion that the prevalence of COPD is declining is also supported by declines in health service use and deaths due to COPD.

Notes  

1. COPD occurs mostly in people aged 55 years and over. While it is occasionally reported in younger age groups, in those aged 55 years and over there is more certainty that the condition is COPD and not another respiratory condition. For this reason only people aged 55 years and over are included in this graph.
2. The age group 55 years and over is age standardised to the population as at 30 June 2001.
3. The thin vertical bars attached to the top of each column are 95% confidence intervals. We can be 95% confident that the true value is within the interval depicted.

Source: AIHW analysis of Australian Bureau of Statistics National Health Survey, 2007–08.

Reference

Buist A, McBurnie M, Vollmer W, Gillespie S, Burney P, Mannino D et al. 2007. International variation in the prevalence of COPD (The BOLD Study): a population-based prevalence study. The Lancet 370:741-50.

Source table

Notes  

1. COPD occurs mostly in people aged 55 years and over. While it is occasionally reported in younger age groups, in those aged 55 years and over there is more certainty that the condition is COPD and not another respiratory condition. For this reason only people aged 55 years and over are included in this graph.
2. 95% confidence intervals (95% CI) indicate the range witnin which we can be 95% confident that the true value lies within.
3. The age group 55 years and over is age standardised to the population as at 30 June 2001.

Source: AIHW Analysis of Australian Bureau of Statistics National Health Survey, 2007–08.