Beyond smoking in COPD: an etiotype-based approach across the life course and its use in primary care: a narrative review

Abstract Chronic obstructive pulmonary disease (COPD) is a heterogeneous lung disease. It is characterized by chronic respiratory symptoms and persistent airflow obstruction. Cigarette smoking remains the most important preventable risk factor in many populations. However, COPD cannot be explained by smoking alone. Poor lung development, early-life respiratory problems, asthma, household air pollution, biomass smoke, outdoor air pollution, occupational dusts and fumes, tuberculosis, recurrent respiratory infections, bronchiectasis, and genetic susceptibility may also contribute to COPD. The current Global Initiative for Chronic Obstructive Lung Disease (GOLD) report should be used as the most recent global strategy document for COPD diagnosis, prevention, and management. However, the GOLD 2023 taxonomy and the Lancet Commission provide an emerging etiological framework for understanding the multiple pathways that may contribute to COPD. In this context, etiotypes refer to proposed causal or contributory pathways associated with the development of COPD. These proposed pathways include genetic susceptibility, abnormal lung development, cigarette smoking, biomass and pollution exposure, infection-related pathways, asthma-associated persistent airflow limitation, and disease of unknown cause. These categories are not mutually exclusive. In real-world primary care, more than one pathway may be present in the same patient. Therefore, clinical assessment should not stop after asking whether the patient has smoked or not. Social and economic determinants may further shape these pathways by influencing early-life lung development, household and occupational exposures, infection risk, access to spirometry, health literacy, and treatment adherence. This narrative review discusses COPD etiotypes from a life-course and primary care perspective. It presents a practical etiotype-informed assessment framework linking major causal pathways with key history-taking questions and primary care actions. This approach may support targeted case finding rather than population screening, guide spirometry referral, identify modifiable exposures, reduce smoking-related stigma, and help determine when early pulmonology referral is needed.