MeiLan K. Han, MD, MS, associate professor of medicine at the University of Michigan Health System (UMHS), and colleagues have determined that there is an association between a patient’s bronchial wall thickness and degree of air sac destruction on CT with frequency of exacerbation,
Han analyzed data from the COPDGene Study , an ongoing multicenter NHLBI-sponsored study designed to identify genetic factors associated with COPD. In the study, patients who are between 45 and 80 years old with a history of cigarette smoking undergo spirometry and whole-lung volumetric CT examinations to determine why some smokers develop COPD and others do not.
The UMHS study group included the first 2,500 patients enrolled in the COPDGene study who met criteria for COPD.
The analysis revealed that while many patients had a mixture of structural changes related to their COPD, two subgroups predominantly with emphysema or large airway disease could be identified, and both increased airway wall thickness and increased emphysema were associated with greater exacerbation frequency, independent of spirometric measures of lung function.
Spirometry is currently the standard for diagnosing COPD, but it is inadequate as the sole parameter for assessing risk of exacerbations, according to Han.
“Two COPD patients may be identical in terms of lung function yet behave very differently. For instance, there are subsets of patients with severely reduced lung function who do not experience frequent exacerbations,” says Han, adding, “Radiologic characterization of COPD patients has prognostic value in the selection of more homogeneous subgroups for clinical trials and possibly for identifying patients at risk of frequent exacerbation for targeted medical therapies.”
For more about the COPDGene Study, read “12 Million Patients, 10,000 Subjects, So Few Easy Answers.”