Electronic cigarette use and respiratory symptoms in the French population-based Constances cohort

Background: Knowledge about the consequences of electronic cigarette (EC) use on respiratory health is still limited. We aimed to assess whether EC use is associated with the occurrence of asthma symptoms and chronic bronchitis among the French adult population, with a specific focus on never combustible cigarettes (CC) smokers. We further investigated whether the association differed in men and women. Methods: Constances is a population-based cohort of adults aged 18-69 years at inception. We analyzed baseline data collected in 136,276 participants recruited in 2015-2019. Associations of current and former EC use with respiratory symptoms (asthma symptom score and chronic bronchitis) were assessed, controlling for CC smoking, cannabis use, demographics, education and body mass index (BMI). Results: Increased frequencies of respiratory symptoms were observed in both current and former EC users (for the asthma symptom score, adjusted mean score ratio (aMSR): 1.34 [95 % confidence interval: 1.28-1.41] and 1.39 [1.33-1.45], respectively; for chronic bronchitis, adjusted prevalence ratio (aPR): 1.27 [1.19-1.36] and 1.40 [1.32-1.48], respectively). Among never CC smokers, ever EC use was associated with an increased asthma symptom score in both men and women (aMSR = 1.44 [1.09-1.90] and 1.36 [1.01-1.83], respectively), and with a higher prevalence of chronic bronchitis only in women (aPR = 1.97 [1.27-3.05]). Conclusion: EC use is associated with symptoms of asthma and chronic bronchitis, independently of CC smoking and cannabis use. The fact that these associations are observed among individuals who have never smoked tobacco adds further evidence of the deleterious effects of EC on respiratory health.