In a study conducted in the US, long-term smokers exhibited symptoms that did not align with existing tobacco-related disease criteria.
The research, carried out by the University of California-San Francisco (UCSF), included 1379 participants aged 40 to 80 years, all of whom had smoked one pack of cigarettes a day for at least 20 years.
Surprisingly, half of these individuals showed persistent respiratory symptoms such as shortness of breath, daily cough and phlegm, and reduced exercise capacity.
Despite these symptoms, they performed well in breathing tests commonly used to diagnose chronic obstructive pulmonary disease (COPD), a condition typically associated with long-term tobacco exposure.
COPD diagnosis is commonly based on spirometry, a test that measures lung function by assessing how effectively a person can fill and empty their lungs during maximum effort.
"We found that many people who have a lot of primary tobacco exposure have the same symptoms as people who have COPD, but can't be diagnosed with COPD," said William McKleroy, first author of the study published in the Journal of the American Medical Association (JAMA).
This, he said, was because they performed normally in spirometry.
After this 5-year study, the participants were followed-up for the next 3-4 years, and some for 5 to 10 years after their original visit.
The tests included spirometry, 6-minute walk distance testing, assessment of respiratory symptoms, and CT scans of their lungs.
Some of the participants were found to have COPD after undergoing spirometry, while others had "preserved spirometry", meaning they did not have COPD.
The pulmonary 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 over the course of the study.
Further, symptomatic TEPS participants did not have increased COPD incidence compared to the asymptomatic TEPS ones.
They also did not exhibit a faster rate of lung function decline, measured by the exhaled volume of air forced out in the first second.
Participants with COPD, however, did display a faster rate of lung function decline compared to symptomatic TEPS participants.
"These findings suggest that a large proportion of tobacco smoke-exposed persons without airflow obstruction have a 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) demonstrates a major gap in effective and compassionate care for tobacco-exposed persons and highlights the need for further study to find ways to help them," said McKleroy.
(PTI)
