Chronic obstructive pulmonary disease (COPD) is classically associated with smoking. However, as many as half of COPD cases are among non-smokers, particularly in the developing countries, where other risk factors such as infections, occupational exposure, air pollution both indoor and ambient, are more prevalent.

Researchers from South Korea conducted a study to characterise the clinical features of smoking and non-smoking patients with COPD. The differences in terms of symptoms, exercise capacity, imaging findings, pulmonary function and acute exacerbations were also defined for the two patient groups.¹

For this, data of 2477 patients was obtained from the multicenter, prospective, observational Korea COPD Subgroup Study (KOCOSS) database. The enrolled participants were examined at baseline and at intervals of 6 month. Majority (91.9%) of the participants were smokers, while the remaining 8.1% were non-smokers. Radiological findings were described as emphysematous changes, TB-destroyed lung, airway wall thickening or bronchiectasis. PFTs were done at the start of the study and then every year.

Results published in the Journal of Chronic Obstructive Pulmonary Disease show that women were more likely to be diagnosed with non-smoking COPD. BMI was higher in the non-smoking COPD group, which also had greater prevalence of comorbid conditions such as osteoporosis, hypertension and gastroesophageal reflux disease. History of respiratory and allergic diseases, including bronchiectasis, TB childhood respiratory infection and asthma was more common among the non-smoking patients. They were also less educated. However, no between-group differences were observed for exacerbation rates, symptom scores, or exercise capacity scores. While the absolute FEV1 was lower among the non-smoking patients, the % predicted value was not much different between the two groups. However, lung function diminished more rapidly among the smoking patients over 5 years of follow-up.

When radiological features were compared, emphysematous changes were seen more often in the lungs of smokers, while the findings of tuberculous destroyed lung and bronchiectasis were more prevalent among the non-smokers. While airway wall thickening was noted more often in the non-smoking group, this difference was non-significant.

This study elucidates on the differences in clinical features and radiological findings between the non-smoking and smoking COPD patients. While smoking is the major risk factor for COPD, not all COPD patients are smokers. The percentage of COPD in never smokers is rising, particularly in  developing countries like ours. Women in the rural areas are at risk due to exposure to biomass smoke.  Hence, non-smoking COPD should be considered on par with smoking COPD and managed carefully.

Reference

1. Joon Young Choi, et al. Clinical characteristics of non-smoking chronic obstructive pulmonary disease patients: findings from the KOCOSS Cohort. COPD. 2022;19(1):174-181. doi: 10.1080/15412555.2022.2053088.