Symptomatic current or former smokers with preserved lung function, even if they do not meet the criteria for COPD, experience exacerbations and activity limitation.
To investigate smokers with normal lung function and COPD symptoms, the researchers conducted an observational study with 2,736 participants, including current or former smokers and a control group made up of patients who had never smoked. The researchers measured the participants’ respiratory symptoms using the COPD Assessment Test.
Specifically, they examined whether current or former smokers with preserved pulmonary function, as determined by spirometry, had a higher risk for respiratory exacerbations than current or former smokers with preserved lung function who were without symptoms. In addition, the researchers examined whether those with symptoms produced different results from the asymptomatic group in 6-minute walking distance, lung function or high-resolution CT chest scan.
According to the researchers, respiratory symptoms were present in 50% of the current or former smokers with preserved lung function. In addition, the mean rate of respiratory exacerbations among the symptomatic smokers was higher than the rates among those who were asymptomatic or in the control group (0.27 ± 0.67 vs. 0.08 ± 0.31 and 0.03 ± 0.21 events, respectively, per year; P < .001 for both comparisons). Current or former smokers who were symptomatic, regardless of their history of asthma, experienced greater limitation of activity, slightly lower FEV1, FVC and inspiratory capacity, and greater airway-wall thickening without emphysema compared with those without symptoms. Among current or former smokers with symptoms, 42% used bronchodilators and 23% used inhaled glucocorticoids.
“Respiratory symptoms and exacerbations are common in current or former smokers who have spirometric values that are generally considered to be within the normal range,” Prescott G. Woodruff, MD, and colleagues wrote. “Many of these patients are already being treated with respiratory medications despite a lack of data from clinical trials. This finding suggests that the current use of spirometry to define who should receive a diagnosis of COPD may not adequately cover the breadth of symptomatic smoking-related lung disease.”