The criteria used to diagnose chronic obstructive pulmonary disease (COPD) should be expanded beyond measurements of lung function, a new study suggests.
The current criteria for diagnosing COPD is based largely on the assessment of lung function, through a method called spirometry.
The new proposal suggests adding other parameters to patient assessment, namely environmental exposure (i.e., smoking and other environmental factors that can increase COPD risk), patient-reported symptoms (such as shortness of breath, coughing, etc.), and abnormalities on computed tomography (CT) scans (such as thickening of the walls in the lung, emphysema, etc.).
The proposal is based on data from the COPD Genetic Epidemiology study (COPDGene), including data from 8,784 current and former heavy smokers. All participants in the study were Caucasian or African American, 45 to 80 years old, and all had smoked at least 10 pack-years (the average number of packs per day multiplied by the number of years smoking).
Study participants were followed for up to five years.
Researchers used statistical analyses to determine the risk of disease progression (i.e., a clinically relevant decline in lung function), or mortality at five years, compared to a control group composed of heavy smokers without symptoms or evidence of disease.
Results showed that smokers who met any one of the other three criteria — clinical symptoms, chest CT imaging, or spirometry — had a 26% higher risk of lung function decline, and a 28% higher risk of mortality within five years, compared with smokers meeting no additional criteria.
Smokers who met any two additional criteria had a 88% higher chance of losing significant lung function, and a 89% greater chance of dying.
Those who met all three additional criteria (besides smoking) were 188% more likely to experience significant lung function decline over five years, and had over a fivefold increased mortality risk.
It should be noted that these values are somewhat general, as the risk did vary depending on which of the specific criteria were met.
Overall, the team proposed that, among smokers, meeting one of the other three criteria (spirometry abnormalities, CT abnormalities, or COPD-like symptoms) should be deemed “possible COPD;” meeting any two criteria should be considered “probable COPD;” and meeting all four criteria (including smoking) should be considered “definite COPD.”
“Our proposed diagnostic criteria better capture the full spectrum of people suffering from COPD. This can lead to better care for patients and stimulate research to slow or stop progression of the disease or even prevent it,” James Crapo, MD, senior author of the study, said in a press release.
According to the team, if the new diagnostic criteria are used, it could increase by 15%–36% the number of patients diagnosed with COPD in the U.S. (up to additional five million people), and promote better care.
“If we diagnose COPD based only on impaired lung function, then we miss many patients in the early stages of the disease. While some physicians do empirically treat patients with symptoms, many patients are not getting therapy that can improve their symptoms, their quality of life, and might extend their lives,” Crapo said.
“Right now people who do not meet the current diagnostic criteria for COPD are not included in clinical trials of experimental COPD therapies. Our proposed diagnostic criteria could open clinical trials to these people, stimulate important research of potential therapies to slow, stop or even prevent progression of the disease,” Crapo concluded.
The team noted that future analyses are needed to figure out the best criteria for non-smokers (who constitute about 15% of COPD cases), and to determine whether these findings apply in ethnicities not included in the COPDGene study.