Symptomatic current or former smokers with preserved pulmonary function experience exacerbations, activity limitation, and evidence of airway disease, despite not meeting the current criteria for chronic obstructive pulmonary disease (COPD). This according to an observational study of 2,736 current or former smokers and controls who had never smoked and measured their respiratory symptoms using the COPD Assessment Test (scores range from 0 to 40, with higher scores indicating greater severity of symptoms). Researchers found:

• 50% of current or former smokers with preserved pulmonary function had respiratory symptoms.

• The mean rate of respiratory exacerbations among symptomatic current or former smokers was significantly higher than the rates among asymptomatic current or former smokers and among controls who never smoked.

• Symptomatic current or former smokers, regardless of history of asthma, had greater limitation of activity, slightly lower forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), and inspiratory capacity, and greater airway-wall thickening without emphysema.

Citation: Woodruff PG, Barr G, Bleecker E, et al. Clinical significance of symptoms in smokers with preserved pulmonary function. N Engl J Med. 2016;374:1811-1821. doi:10.1056/NEJMoa1505971.

Commentary: COPD is usually identified in clinical practice by persistant respiratory symptoms, often in a current or former smoker, and then confirmed on pulmonary function testing. Part of the definition of COPD is that on spirometry a patient has an FEV₁/FVC ratio <0.70 after bronchodilator use. The severity of COPD is then graded as GOLD stages 1-4 based on the degree of decrement in FEV₁. It has been a clinical observation for years that some smokers have frequent symptoms, but do not meet the criterion of an obstructive deficit. In this study, respiratory symptoms occurred in 50% of current or former smokers with preserved pulmonary function. This study clarifies that although this group does not meet traditional criteria for COPD, they behave much like those who have traditional COPD in that they have limitation of activity as well as experience exacerbations. The usual respiratory medications for COPD, including beta-agonists and inhaled steroids have not been studied in this group, so while those medicines are still often used for this group, it is a group that warrants further study to describe the optimal therapies for care. —Neil Skolnik, MD