https://www.ncbi.nlm.nih.gov/pubmed/31375364
"In a 2012-2014 baseline online e-cigarette survey, 1,863 respondents consented to participate in future research. A follow-up online survey was conducted in 2017-2018 to assess changes in e-cigarette use behaviors and e-cigarette-related dependence.
CONCLUSIONS:
Findings suggest that the risk of relapse to cigarette smoking is low, and e-cigarette-related dependence remains stable in long-term e-cigarette users."
"In a 2012-2014 baseline online e-cigarette survey, 1,863 respondents consented to participate in future research. A follow-up online survey was conducted in 2017-2018 to assess changes in e-cigarette use behaviors and e-cigarette-related dependence.
CONCLUSIONS:
Findings suggest that the risk of relapse to cigarette smoking is low, and e-cigarette-related dependence remains stable in long-term e-cigarette users."
