Abstract
To date no study has reported U.S. nationally representative estimates of current ENDS users by device category ("open" vs. "closed" systems) nor their detailed use behaviors. We examined the proportion of current adult ENDS users (unweighted n = 2671) using either "closed" or "open" systems during Wave 3 (2015-2016) of the Population Assessment of Tobacco and Health (PATH) Study. Demographic characteristics, use patterns, and device characteristics were examined overall and by device type. Among the 5.0% of current users at Wave 3, 43.9% used closed systems and 53.7% used open systems. Compared to closed system users, open system users were more likely to be male (60.7% vs. 48.4%), aged 18-24 (30.4% vs. 21.4%), and non-Hispanic White (76.2% vs. 65.4%), recent former (9.9% vs. 5.6%) or long-term former (20.2% vs. 10.9%) smokers, and use ENDS daily (44.1% vs. 22.5%); they were less likely to be to be current daily smokers (31.7% vs. 48.0%) or never smokers (15.2% vs. 19.5%). Adult ENDS users were nearly evenly split on their use of closed versus open systems; however, several group differences were observed. Disentangling the relationship between device selection and subsequent use patterns remains a public health priority.