COPDGene Study Reveals Important Information About Small Airway Disease

02 Mar COPDGene Study Reveals Important Information About Small Airway Disease

More than 10,000 cigarette users, with and without COPD (chronic obstructive pulmonary disease) participated in a study called the COPDGene study, whose purpose was to explore genetic associations with the disease. Each participant submitted to a CT (or CAT) scan of the chest, and the collective data was analyzed by a team of researchers from the Los Angeles Biomedical Research Institute and other COPDGene investigators , to determine relationships between genetics and COPD physiology.

The study revealed information regarding Small Airway Disease (SAD), a condition thought to affect respiratory function, and therefore an important aspect of both COPD and asthma. Over the years a variety of tests have been employed to establish whether a patient has SAD, including impulse oscillometry (iOS), plethysmography, FEV₃ (Forced Expiratory Volume over 3 seconds), and CT imaging with air-trapping. Until now, comparisons between the modalities has been sparse. Data from the COPDGene study revealed that FEV₃ and CT correlated well in determining whether a patient had SAD – an important finding.

Researchers also found that FEV₃/FEV₆ was superior to FEV₃/FVC for predicting clinical outcomes in patients with COPD. (FVC and FEV₆  are measures of Forced Vital Capacity – overall and after 6 seconds during a spirometry test.) Among patients with otherwise normal spirometry (normal FEV₁/FVC), the 15.4% with a low FEV₃/FVC₆  were not able to perform a 6-minute walk for as great a distance as those with normal FEV₃/FVC₆.

This last finding has great significance, as it demonstrates a clear relationship between the diagnostic measurement and the effect of SAD on the patient’s physical function.

There is a good argument to be made for employing FEV₃/FEV₆ as the preferred method for assessing small airway disease; it’s easy to do as is part of spirometry, it doesn’t require advanced equipment like iOS or plethsymography, and it doesn’t pose a radiation risk. Pulmonologists treating patients who are tobacco users or who have unexplained dyspnea, would do well to perform a spirometry test and look at the FEV₃/FEV₆  to aid diagnosis.

Information for this article was obtained from MEDSCAPE.