About half of current or former smokers have respiratory symptoms similar to COPD, but lung function measured using spirometry fails to give a clinical diagnosis, which delays early treatment intervention.
COPD, or chronic obstructive pulmonary disease, is the third leading cause of death in the United States. Researchers have long observed that some current and former smokers appear to have respiratory symptoms associated with COPD—such as coughing and shortness of breath—despite having normal spirometry results that measure the amount of air a person breathes out and how fast. However, the extent and clinical implications of the problem weren’t known until now.
In a paper published in the New England Journal of Medicine, a multi-institutional research team conducted an observational study called SPIROMICS (Subpopulations and Intermediate Outcome Measures in COPD Study) that included patient data collected between 2010 and 2015. The scientists examined respiratory symptoms and measured lung function with spirometry in 2,736 participants—current or former smokers aged between 40 and 80 years old, as well as controls who had never smoked. Respiratory symptoms were present in about half of the current or former smokers, despite normal spirometry readings.
The study used lung CT scans overseen by the University of Iowa SPIROMICS Radiology Center and analyzed at the VIDA Diagnostics Core Lab in the Bioventures Center of the UI. The CT scans of participants with COPD-like symptoms but normal spirometry readings showed a high incidence of thickening of the airways, a sign of lung disease.
“The study shows that quantitative CT scans can provide insights into underlying lung disease processes and suggests that lung function tests should not necessarily serve as the only test for diagnosing COPD and guiding treatment,” says Eric Hoffman, PhD, UI professor of radiology and director of the Advanced Pulmonary Physiomic Imaging Laboratory, home to the SPIROMICS Radiology Center.