The role of electronic cigarette use for quitting or reducing combustible cigarette use in the 30s: Longitudinal changes and moderated relationships

Background
Evidence for use of electronic cigarettes (e-cigs) as a potential aid in quitting or reducing combustible cigarette (c-cig) use is mixed. This study examined the extent to which e-cig initiation among smokers in their 30 s predicted quitting or reducing smoking or nicotine dependence symptoms by age 39, and whether the role of e-cigs in quitting differed by prospectively assessed moderators.
Methods
Data were from the Seattle Social Development Project (SSDP), a panel study of 808 diverse participants with high retention. A subsample of 221 smokers at age 33 was selected for analysis. Self-reports of c-cig use and dependence were assessed longitudinally at ages 33 and 39. Sixteen potential moderators were examined, including social demographics, smoking attitudes and desire to quit, other health behaviors and status, and adolescent and early adult assessments of smoking history.
Results
The use of e-cigs was consistently associated with a lower likelihood of quitting c-cigs by age 39, after accounting for frequency of prior c-cig use at age 33. This negative association persisted across all moderators examined, although it was nonsignificant among those with a definite desire to cut down. Among those who did not quit smoking, e-cig use had no association with decreases in either quantity of c-cigs used or dependence symptoms.
Conclusions
Results indicate that e-cigarette use was not helpful for quitting or reducing combustible cigarette use in the 30 s. Rather, across extensive tests of moderation, e-cig initiation consistently predicted less quitting during this important age period for successful cessation.