E-cigarette use and subsequent asthma outcomes in patients with current asthma: Findings from the National Asthma Survey

<bold>Introduction</bold>: The use of e-cigarette potentially increases the risk of asthma, yet little is known about its effects on subsequent asthma outcomes. <bold>Objectives</bold>: To investigate the relationship between e-cigarette use and subsequent asthma-related outcomes. <bold>Methods:</bold> We used data from Behavioral Risk Factor Surveillance System Asthma Call-back Survey to compare the demographic and clinical characteristics of the patients who use or not use e-cigarettes. Multivariable regression was further applied to estimate associations between e-cigarette use and asthma-related outcomes, which include asthma attack, symptom control and health related quality of life. <bold>Results:</bold> Of 18 827 participants with current asthma in our research, there were 3295 (17.5%) e-cigarette users and 15 532 (82.5%) never e-cigarette users. Compared with never users, the proportion of the asthmatics with asthma attack, uncontrolled symptom and impaired health related quality of life was higher in e-cigarette users. After adjusting potential confounders, the e-cigarette use was associated with increased risk of asthma attack (adjOR = 1.19, 95%CI: 1.08-1.31), uncontrolled symptom (adjOR = 1.38, 95%CI: 1.24, 1.53) and impaired health-related quality of life (poor self-rated health: adjOR = 1.23, 95%CI: 1.10, 1.38; impaired physical health: adjOR = 1.23, 95%CI: 1.10, 1.38; impaired mental health: adjOR = 1.33, 95%CI: 1.18, 1.50; limited activity: adjOR= 1.12, 95%CI: 1.01, 1.24). <bold>Conclusions:</bold> E-cigarette use may affect subsequent asthma-related outcomes. It is associated with increased risk of asthma attack, uncontrolled symptom and impaired health-related quality of life.