The impact of smoking on the lungs and the individual is substantially underestimated when using lung-function tests alone, and lung disease is common in smokers whose lung-function tests fall within population norms, according to a study by James D. Crapo, MD, professor of medicine at National Jewish Health, and colleagues.

The team analyzed data from the Genetic Epidemiology of COPD cross-sectional observational study of 8,872 adults aged 45 to 80 years who had smoked at least a pack of cigarettes a day for 10 years.

Based on their evaluation of 8,872 smokers, 55% of the participants who were labeled as disease-free based on lung function tests actually had some form of respiratory related impairment.