COPD cannot be definitively diagnosed without pulmonary function studies. When these studies are performed, we can grade the disease by what is called the GOLD scale which runs from 0 to 4. Patients who are 0 may be at risk, but generally are not felt to have the disease. Researchers with the COPD Gene study may have found otherwise. They suggest that as many as 35 million current and former smokers older than age 55 years in the US may have some form of respiratory impairment associated with smoking and COPD, which has gone undiagnosed with a standard breathing test called a spirometry.
Spirometry is a test where patients are asked to blow into a testing machine and measurements of airflow are made. The standard testing may not be adequate to diagnose early COPD patients. Of the 4,388 current and former smokers older than age 55 years who did not meet the usual testing definition of COPD, 55% had significant respiratory disease. Other measurements and histories may need to include a history of chronic bronchitis, severe and frequent respiratory exacerbations, findings of emphysema on CT scans of the chest, so-called air trapping on more sophisticated lung function testing, shortness of breath on exertion, and failure to walk at least 350 meters in 6 minutes.
Patients often ask why testing in our lab is more complete and why CT scans are requested. Information from the COPD Gene project supports these efforts. We now need to translate these finding into appropriate therapies.