‘Demonstrable’ lung function decline over 10 years in current, former smokers: COPDGene

Ten-year follow-up data from the COPDGene study show that changes in lung function, respiratory symptom burden and functional capacity in current and former smokers appear to be slow.

However, changes over time in patients with normal baseline spirometry almost neared that of participants with COPD, researchers reported in the Annals of the American Thoracic Society.

“Although change in the group as a whole is slow, there is a demonstrable loss of lung function, increase in respiratory symptom burden and decrement in functional status among many subgroups examined in both current and former smokers,” Margaret F. Ragland, MD, MS, critical care medicine specialist at Virginia Mason Medical Center, Seattle, and colleagues wrote. “This suggests that many former and current cigarette smokers, even those without a COPD diagnosis, are at risk for lung function decline, development of respiratory symptoms and loss of functional capacity that may have a significant impact on quality of life and amount of function.”

Researchers analyzed longitudinal data from 9,103 participants from the COPDGene study without changes in smoking status over three visits during 10 years of follow-up. Researchers examined FEV₁, St. George’s Respiratory Questionnaire (SGRQ) and 6-minute walk distance from COPDGene phase 1 to phase 3.

At enrollment, the mean age of participants was 59.8 years, 46% were women and 32.6% were Black.

FEV₁ and 6-minute walk distance decreased and SGRQ scores increased during 10 years of follow-up among all Global Initiative for COPD (GOLD) COPD groups, including participants with normal spirometry at baseline, the researchers reported.

Current smokers had a greater mean FEV₁ loss over 10 years compared with former smokers for all GOLD COPD groups, excluding those with preserved ratio impaired spirometry, according to the results.

Researchers reported similar rates of progression in SGRQ score and 6-minute walk distance among former and current smokers. However, 6-minute walk distance was higher among participants in the highest COPD severity groups; former smokers had greater progression, the researchers wrote. This finding may be impacted by including current smokers with faster progression who quit smoking and eventually were dropped from the analysis, the researchers wrote.

“Our results may be more conservative than would be seen in a general population because of the fact that we are studying older participants and more rapid change may have occurred early in their course of disease. It is also possible that medications are altering the natural history of disease, and we are observing slower progression than historical studies have seen. In future work, we plan to study methods that distinguish missing data due to death and dropout, such as fully and partly conditional models on survival status,” the researchers wrote.