Prevalence of chronic obstructive pulmonary disease (COPD) in asymptomatic smokers is 1.5% and these individuals would benefit from early interventions — both therapeutic and smoking cessation counseling, according to the results of a study recently published in the International Journal of COPD.

Chronic obstructive pulmonary disease is characterized by a poorly reversible limitation in airflow, and is predicted to be the third most frequent cause of death worldwide by 2020. The diagnosis and risk of death in patients with COPD is usually estimated with the use of the forced expiratory volume in 1 second (FEV1 ). However, physicians do not routinely recommend smokers undergo spirometry unless they are symptomatic — particularly when they present with dyspnea (shortness of breath).

To test if a significant number of asymptomatic smokers indeed had COPD, in the study entitled “Prevalence of chronic obstructive pulmonary disease in asymptomatic smokers,” Alejandra Ramírez-Venegas and co-researchers estimated the prevalence of COPD in a group of 2,961 smokers with symptoms and those without symptoms (WOS). All participants had a cumulative consumption history of at least 10 pack-years (with pack years being the number of packs of cigarettes smoked daily multiplied by the number of years smoked), and were invited to perform a spirometry and complete a symptom questionnaire.

The researchers found that 21.5% of the participants had no symptoms, whereas 78.5% had at least one symptom. The prevalence of COPD in WOS study participants was 1.5% when considering the whole group of smokers, and 7% when considering only the asymptomatic group. Of the 329 smokers found to have COPD, 13.7% were WOS.

The asymptomatic smokers were found to be younger, with a better lung function and a lower cumulative consumption of cigarettes. According to severity of airflow limitation, 69% versus 87% of subjects were classified as Global Initiative for Chronic Obstructive Lung Disease stages I–II in the WOS and symptomatic groups, respectively. The results also revealed that forced expiratory volume in 1 second (mL) was the only predictor for COPD in asymptomatic smokers.

Growing clinical positions state the need for “early and earlier” COPD diagnosis in order to prevent late disease consequences. Most of these are based on case-finding strategies where symptoms and history of heavy tobacco smoking are the main indicators for spirometry.

“Our results suggest that a number of asymptomatic smokers may be excluded from the benefit of an ‘early’ intervention, not just pharmacological but also from smoking cessation counseling. Therefore, screening all heavy smokers aged >40 years with a history of >20 pack-years, WS or WOS, with spirometry, may help to resolve the universal issue of underdiagnosed COPD,” the researchers concluded.