Electronic Cigarette Use and Respiratory Symptoms in Adolescents.

RATIONALE Rates of adolescent electronic (e-) cigarette use are increasing, but there has been little study of the chronic effects of use. Components of e-cigarette aerosol have known pulmonary toxicity. OBJECTIVES To investigate the associations of e-cigarette use with chronic bronchitis symptoms and wheeze in an adolescent population. METHODS Associations of self-reported use of e-cigarettes with chronic bronchitic symptoms (chronic cough, phlegm, or bronchitis) and of wheeze in the previous 12 months were examined in 2,086 Southern California Children's Health Study participants completing questionnaires in 11th and 12th grade in 2014. MEASUREMENTS AND MAIN RESULTS Ever e-cigarette use was reported by 502 (24.0%), of whom 201 (9.6%) used e-cigarettes during the last 30 days (current users). Risk of bronchitic symptoms was increased by almost twofold among past users (odds ratio [OR], 1.85; 95% confidence interval [CI], 1.37-2.49), compared with never-users, and by 2.02-fold (95% CI, 1.42-2.88) among current users. Risk increased with frequency of current use (OR, 1.66; 95% CI, 1.02-2.68) for 1-2 days and 2.52 (95% CI, 1.56-4.08) for 3 or more days in past 30 days compared with never-users. Associations were attenuated by adjustment for lifetime number of cigarettes smoked and secondhand smoke exposure. However, risk of bronchitic symptoms among past e-cigarette users remained elevated after adjustment for relevant potential confounders and was also observed among never-cigarette users (OR, 1.70; 95% CI, 1.11-2.59). There were no statistically significant associations of e-cigarette use with wheeze after adjustment for cigarette use. CONCLUSIONS Adolescent e-cigarette users had increased rates of chronic bronchitic symptoms. Further investigation is needed to determine the long-term effects of e-cigarettes on respiratory health.