Phenotypic Differences between Patients with Smoking Chronic Obstructive Pulmonary Disease and Non-smoking Chronic Obstructive Pulmonary Disease

Background: In low- and middle-income countries, causes other than tobacco smoking contribute more to the development of chronic obstructive pulmonary disease (COPD). In India, non-smoking-related COPD (NS-COPD) is common due to the high prevalence of pulmonary tuberculosis and biomass fuel exposure. Our study aims to know the phenotypic differences between smoking-related COPD (S-COPD) and NS-COPD patients. Materials and Methods: The study included 217 patients, who visited the outdoor department of a tertiary care center. A detailed clinical history was obtained; radiological and hematological investigations, spirometry, and a 6-min walk test were performed. Results: Of 217 patients, 100 had S-COPD, and 117 had NS-COPD. Male patients were predominantly affected (P < 0.001) in both groups. There were significant differences in the age group (P < 0.001), body mass index (P < 0.045), blood hemoglobin levels (P < 0.02), forced vital capacity (FVC) (P = 0.02), postbronchodilator reversibility in forced expiratory volume in 1 s (FEV1) (P < 0.006), and FEV1/FVC ratio (P < 0.001) between patients with smoking and S-COPD and NS-COPD. Emphysema was more common in S-COPD, whereas COPD-bronchiectasis overlap was more common among NS-COPD patients. Cough was more common, and airflow obstruction was less severe in nonsmokers. There was no significant difference in the exercise capacity. Conclusion: The NS-COPD patients present at younger age, with more COPD-bronchiectasis overlap phenotype. They have less severe airflow obstruction and more postbronchodilator reversibility. Understanding phenotypic characteristics is necessary for accurate diagnosis and management of COPD in nonsmokers.