Factors Associated with Electronic Cigarette Use and Pulmonary Function Outcomes: A Cross-Sectional Analysis of Korean National Health and Nutrition Examination Survey Data from 2013 to 2019

Abstract Background Significant differences exist between the toxicity and adverse outcomes of conventional cigarettes and electronic cigarettes (e-cigarettes). However, spirometry-based clinical outcomes analyses in the general population have not been widely studied. This study aimed to investigate the factors associated with e-cigarette use among individuals with different smoking statuses and pulmonary function test (PFT) results. Methods This study was conducted in Korea using data from the Korean National Health and Nutrition Examination Survey from 2013 to 2019. Participants who reported baseline clinical information, including smoking status, and underwent a PFT were included. Results In total, 19,356 participants, including current smokers, former smokers, and those who had never smoked, were included in this study. Among those who smoked, 5.7% reported current e-cigarette use, including dual users (who use conventional cigarettes and e-cigarettes). Factors associated with e-cigarette use included male sex, younger age, higher education level, higher household income, and current or former heavy smoker. Additionally, cigarette users had the highest prevalence of chronic obstructive pulmonary disease (COPD), followed by dual users and e-cigarette-only users (p < 0.001). Furthermore, individuals with anxiety and depression were significantly more prevalent among dual users compared with those who had never smoked (p < 0.001). Conclusions This study indicates an association between e-cigarette use and individual factors, including sex, age, education level, and income level. E-cigarette use, including dual use, is associated with COPD. Additionally, anxiety and depression were highest among dual users, followed by conventional cigarette users.