Chronic obstructive pulmonary disease (COPD) is now the third leading cause of death in the United States. But thanks to a pair of studies supported by the National Heart, Lung, and Blood Institute (NHLBI), scientists are continuing to shed new light on this chronic lung disease in the hope of reducing its impact through a better understanding of the earliest stages of the disease.
COPD is actually a group of lung diseases that includes emphysema and chronic bronchitis. Although symptoms vary depending on the individual, common symptoms include shortness of breath and chronic coughing. In the United States most cases of COPD are due to cigarette smoking.
In the first NHLBI-supported study, scientists with National Jewish Health, a hospital specializing in respiratory disorders, found that COPD may be underdiagnosed in millions of smokers who passed a common test for lung function. The researchers evaluated 8,872 people ages 45 to 80 who were current or former smokers, all of whom had smoked at least the equivalent of a pack of cigarettes a day for 10 years. Using a device called a spirometer, which is used to diagnose COPD by having patients blow as hard as they can into it, the researchers initially found that about half of the participants had normal lung function.
But when the researchers put these patients with normal spirometry through additional lung tests involving imaging, walking, and quality-of-life questionnaires, they found that about 55 percent of these patients were not normal. Many of these had apparent abnormalities in their lungs or in their exercise capability, the researchers note.
“The impact of chronic smoking on the lungs and the individual is substantially underestimated when using lung-function tests alone,” says James D. Crapo, M.D., professor of medicine at National Jewish Health in Denver, Colo., and senior author of the study, which was published in JAMA Internal Medicine. “Lung disease is common in smokers whose lung-function tests fall within population norms.”
The study, which underscores the importance of not smoking, could lead to better screening tests for lung disease in smokers, the researchers say. It also identifies a previously overlooked subgroup, smokers with possible early signs of COPD, who might benefit from early intervention, they note.
“Until now, we didn’t know that this subgroup of smokers with undetected lung disease was so large,” said James Kiley, Ph.D., Director of the NHLBI’s Division of Lung Diseases. “Now that we know how to identify the people with early abnormalities, we can start to test whether intervening sooner will slow the progression of the disease.”
The National Institutes of Health has already begun exploring a possible COPD intervention in this newly identified, at-risk population. A new NHLBI-supported study, being conducted by researchers at the University of Michigan and University of California San Francisco, is currently evaluating whether treatment with inhaled bronchodilator drugs already used in advanced COPD will benefit smokers with mild COPD that is not detectable by spirometry. Bronchodilators are substances that increase airflow to the lungs. This clinical trial, which was funded in September 2015 and is expected to last until 2019, will enroll up to 570 subjects who will receive either bronchodilators or placebo. The bronchodilators used in this trial will be a combination of a long-acting beta agonist (LABA) and a long-acting muscarinic antagonist (LAMA).
Although some of these smokers with undetected lung disease may already be taking some form of bronchodilators to reduce COPD symptoms, there is no clear guidance or evidence that these drugs are beneficial for their condition. If bronchodilators are found to be beneficial, this could open up a whole new chapter in the early treatment of COPD and could alter treatment guidelines, researchers predict.
“We believe that studying early changes in COPD will play a key role in understanding how COPD develops,” said Dr. Kiley. “And just as important, we’ve now identified a subpopulation of patients where new drugs for the early treatment of lung disease can be tested.”