COPD, which is known to be associated with chain smoker long-term tobacco exposure, is assessed using spirometry. It tests lung function by measuring how quickly and efficiently a person fills and deflates the lungs at maximum effort.
In a study conducted in the US, long-term smoking developed symptoms that did not meet any of the existing criteria for tobacco-related disease. The study involved participants who had smoked one pack of cigarettes a day for 20 years or more. 1,379 people between the ages of 40 and 80 were recruited.
Half of them showed persistently high levels of respiratory symptoms such as shortness of breath, daily cough and phlegm, and reduced exercise capacity. Researchers at the University of California, San Francisco (UCSF) found that they performed well in breath tests used to diagnose chronic obstructive pulmonary disease (COPD).
COPD, which is known to be associated with long-term tobacco exposure, is assessed using spirometry. It tests lung function by measuring how quickly and efficiently a person fills and deflates the lungs at maximum effort.
“We found that many people who are primarily exposed to tobacco have the same symptoms as people who have COPD but cannot be diagnosed with COPD,” said William McKleroy, first author of the study published in the Journal of the American. Medical Association (JAMA). He said it was because they were performing normally in the spirometry.
After this 5-year study, participants were followed for an additional 3–4 years, and some for 5–10 years after their original visit. The tests included spirometry, a 6-minute walk distance test, an assessment of respiratory symptoms and a CT scan of their lungs. Some participants were found to have COPD after undergoing spirometry, while others had “preserved spirometry,” meaning they did not have COPD.
The lung symptoms of participants with tobacco exposure and preserved spirometry (TEPS) at the start of the study persisted through more than five years of follow-up, the researchers found. They were also found to have high rates of respiratory exacerbations and shortness of breath, limiting their ability to be active during the study.
Furthermore, symptomatic TEPS participants did not have an increased incidence of COPD compared to asymptomatic TEPS. They also did not show a faster rate of decline in lung function, as measured by the exhaled volume of air pushed out in the first second. However, participants with COPD showed a faster rate of decline in lung function compared to participants with symptomatic TEPS.
“These findings suggest that a large proportion of individuals exposed to tobacco smoke without airway obstruction have persistent, symptomatic non-obstructive chronic airway disease that is distinct from COPD,” said Prescott Woodruff, principal investigator of the initial 5-year study. “This (study) shows a major gap in effective and compassionate care for those exposed to tobacco and highlights the need for further study to find ways to help them,” McKleroy said.
