Clinical characteristics of chronic obstructive pulmonary disease in never-smokers: A systematic review

Chronic Obstructive Pulmonary Disease (COPD) is the third cause of death worldwide. While tobacco smoking is a key risk factor, COPD also occurs in never-smokers (NS). However, available evidence on risk factors, clinical characteristics, and natural history of the disease in NS is scarce. Here, we perform a systematic review of the literature to better describe the characteristics of COPD in NS.