Researchers Propose New Diagnostic Criteria for COPD

Researchers proposed new diagnostic criteria for chronic obstructive pulmonary disease (COPD) that seek to identify more patients in early stages of the disease, promote better care for patients, and stimulate research to slow and prevent COPD, in a paper published today in the journal Chronic Obstructive Pulmonary Diseases.

COPD is a progressive, complex combination of airway inflammation disease, chronic bronchitis, and emphysema, that is as the fourth leading cause of death in the United States. There are myriad factors associated with the development of COPD, with smoking tobacco use cited as the most common. A recent study found that female nurses who are regularly exposed to disinfectants and cleaning products were at a heightened risk of incident COPD, highlighting its expansive capability to affect non-smokers as well.

Nearly 12 million people in the United States have been diagnosed with COPD, with many others thought to have undiagnosed COPD. Currently, COPD is diagnosed by spirometry, a history of exposure, and respiratory symptoms at the time of presentation, but the authors note that disease trajectory can vary from years of stability to devastating acute exacerbations and respiratory failure, with several studies having demonstrated that many smokers without traditional spirometric obstruction were aligned in progression with those who had spirometrically diagnosed COPD.

As every year approximately 120,000 people die from COPD, researchers sought to expand upon current diagnostic criteria amid significant concerns regarding the optimal approach to classify the spectrum of the disease, which the authors cited as including exposure, symptoms, spirometric findings, and image-based assessment of structural abnormalities. Researchers hypothesized that spirometric criteria alone are insufficient to characterize smoking-related disease burden, and proposed several new diagnostic classifications for COPD:

• Identify individuals who are at higher risk of disease progression and mortality
• Inform patients early in the course of the disease
• Identify patients who may benefit from therapy
• Test new therapies to slow or halt disease progression in patients before disability or irreversible lung structural changes develop

Researchers evaluated 8784 smokers and former smokers enrolled in the COPDGene^® study. At the time of enrollment, they documented criteria of patients’ environmental exposures (smoking), symptoms (shortness of breath, chronic cough, and phlegm), structural abnormalities on CT scans (emphysema, gas-trapping, and airway wall thickness), and lung function or spirometry (total volume of air exhaled from the lungs and the volume of air exhaled in 1 second). These measures were then correlated with mortality and loss of lung function after a 5-year follow-up and compared with smokers who did not exhibit criteria beyond smoking history.

Study results showed that, for smokers who met either 1, 2, or 3 additional criteria, all had increased risks of losing significant lung function in 5 years, or mortality. Smokers meeting 1 of the other 3 criteria were categorized as having possible COPD, and had a 26% (odds ratio [OR], 1.26; 95% CI, 1.03-1.53) greater risk of losing significant lung function than smokers meeting no additional criteria, and a 28% (hazard ratio [HR], 1.28; 95% CI, 0.99-1.66) greater chance of dying.

Smokers meeting 2 of the 3 additional criteria were designated as having probable COPD, and had an 88% (OR, 1.88; 95% CI, 1.52-2.32) greater risk of losing significant lung function and an 89% (HR, 1.89; 95% CI, 1.48-2.41) greater chance of dying. Patients meeting all 4 diagnostic criteria were categorized as having definite COPD and exhibited a stark 188% (OR, 2.88; 95% CI, 2.23-3.71) greater chance of losing significant lung function over 5 years and were more than 5 times as likely to die (HR, 5.21; 95% CI, 4.17-6.52).

Senior author James Crapo, MD, coprincipal investigator of the COPDGene^® study, highlighted the fact that, “if we diagnose COPD based only on impaired lung function, then we miss many patients in the early stages of the disease.” Crapo described how the proposed diagnostic criteria would better capture the full spectrum of people suffering from COPD who are not getting therapy that can improve their symptoms, quality of life, and mortality risk.

“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,” said Crapo.

Reference

Lowe KE, Regan EA, Anzueto A, et al. COPDGene 2019: redefining the diagnosis of chronic obstructive pulmonary disease. Chronic Obstr Pulm Dis. 2019; 6(5): 384-399. doi: 10.15326/jcopdf.6.5.2019.0149.