Study objectives: To develop and validate a model based
on smoking rates that will provide reliable estimates of the true
prevalence of COPD that include both clinically detected and undetected
Design: Model based on literature review.
Age- and gender-specific rates of lung impairment by smoking status
were applied to US smoking data. Resultant estimates were compared to
the actual prevalence of obstructive airway disease as estimated by US
national surveys. The model then was applied to estimate the prevalence
of COPD in several European countries, where national data on
undiagnosed lung disease do not exist.
model was adapted from both a literature review and health-care data,
and the analysis was applied to the United States and Europe.
Results: Using smoking rates, we estimate from our model
that 15.3 million people who are > 40 years of age in the United
States have COPD. The prevalence estimate, based on spirometric
definitions for COPD in the same age group using the Third National
Health and Nutrition Examination Survey (NHANES III), is 17.1 million
people. NHANES III and other US national health-care surveys further
suggest that only between 2.4 and 7 million people actually have COPD
diagnosed; thus, the proportion of COPD that is currently being
diagnosed in the United States is between 14% and 46% of all cases.
Using smoking rates and our model, which was developed and validated
for the United States, we calculated the prevalence of COPD
for Germany (2.7 million people), the United Kingdom (3.0 million
people), Spain (1.5 million people), Italy (2.6 million people), and
France (2.6 million people) in those people > 45 years of age.
Conclusions: Smoking rates appear to provide a useful
method of estimating current COPD prevalence in those countries where
more objective data are unavailable. These results are important
because recognition of the true burden of disease and corresponding
efforts to increase early identification of COPD can help to reduce the
morbidity and mortality associated with COPD in populations at