Is e-cigarette use in adolescents associated with continued smoking years later?

In a recent study published in the JAMA Network Open Journal, researchers assessed the relationship between adolescent baseline electronic cigarette usage with continued cigarette smoking two years after initiation.

Study: Association of Electronic Cigarette Use by US Adolescents With Subsequent Persistent Cigarette Smoking. Image Credit: DedMityay/Shutterstock.com

Background

E-cigarettes have gained popularity as tobacco or nicotine products among adolescents in the United States (US). Previous studies documented a positive relationship between adolescent e-cigarette usage and subsequent cigarette smoking initiation.

However, data on whether electronic cigarettes are linked to regular and persistent smoking following initiation are limited. E-cigarette usage among the youth may lead to cigarette-naive adolescent individuals trying smoking, and subsequent addiction to smoking could result in smoking-associated adverse health outcomes.

About the study

In the present longitudinal study, researchers investigated whether adolescent individuals who had used electronic cigarettes at study initiation, compared to adolescents who had not used electronic cigarettes, had greater chances of continuing smoking after two years of initiating the habit.

The study comprised young individuals between 12 and 17 years, participating in the third, fourth, and fifth waves of the national-level population assessment of tobacco and health (PATH) trial. The third study wave was between October 2015 and October 2016, and the fourth was between December 2016 and January 2018. The fifth wave was between December 2018 and November 2019.

All participants did not have cigarette smoking habits before the third study wave. Multivariable logistic regression modeling was performed in August of 2022 to determine the relationship between electronic cigarette usage and continued smoking.

The adjusted odds ratios (aOR) and adjusted risk differences (aRD) were calculated. PATH study data were obtained via audio and computer-aided self-interviews and personal interviews. The study exposures were current (in the previous 30 days).

The prime study outcome was ‘continued smoking during the fifth wave after initiating smoking in the preceding wave.’ Sociodemographic variables included age, sex, ethnicity, school grades, race, parental educational status, and household income. Smoking exposure was assessed through family tobacco usage, peer cigarette smoking, and exposure to second-hand smoke. Data were analyzed in August 2022.

Five binary measures of cigarette smoking were constructed, representing the commitment to smoking: (i) cigarette usage in the previous year [continued smoking measure (CSM)-I); (ii) cigarette usage in the previous 30.0 days (CSM-II); (iii) established cigarette smoking, use of ≥100 cigarettes in a lifetime and current smoking (CSM-III); (iv) using ≥100 cigarettes in a lifetime and smoking for ≥5.0 days in the previous 30.0 days (CSM-IV); and (v) ≥100 cigarettes in a lifetime and smoking for >20 days in the previous 30.0 days (CSM-V).

Results

The study comprised 8,671 adolescent individuals who were naïve to cigarette smoke in the third wave and were participants of the fourth and fifth waves, of which 55% (n=4,823) were 12 to 14 years of age, 51% (n=4,454) were men, and 51% (n=3,763) were Whites of non-Hispanic ethnicity.

Among the study participants, 10% (n=842) of individuals documented ever electronic cigarette usage, and two percent (n=138) documented current electronic cigarette usage.

Irrespective of electronic cigarette usage, 362 adolescents (four percent) began to smoke in the fourth wave, among whom 218 individuals continued to smoke in the fifth wave, belonging to the CSM-I group, and 133, 60, 27, and 12 individuals belonged to CSM-II, CSM-III, CSM-IV, and CSM-V groups, respectively. The third wave weighted response rate was 83%.

An aOR value of 1.80 was observed for ever electronic cigarette usage versus never electronic cigarette for persistent smoking habits post-30 days in the fifth wave. However, the aRD value was 0.90 percent points with no statistical significance for persistent smoking, the risk in absolute terms being one percent for individuals who never used electronic cigarettes and two percent for electronic cigarette users.

An alternate continued smoking measure (≥100 cigarettes smoked in a lifetime and smoking currently in the fifth wave, with the study exposure being baseline current electronic cigarette usage) yielded comparable results.

Using CSM-II, among adolescents who ever used electronic cigarettes in the third wave, six percent of individuals began smoking cigarettes in the fourth wave and continued to smoke in the fifth wave, compared to one percent among those who never used electronic cigarettes. Using CSM-III, four percent of ever electronic cigarette users continued to smoke, compared to one percent of those who never used electronic cigarettes.

Likewise, the prevalence of persistent smoking in the fifth wave was greater among current electronic cigarette users in the third wave. Based on CSM- II and -III, nine percent and seven percent of current electronic cigarette users in the third wave continued to smoke, respectively, compared to 1.40% and 0.70% of non-current electronic cigarette users.

Additionally, age, ethnicity, race, grades in school, tobacco consumption by family members, second-hand smoke exposure, cigarette usage by best friends, usage of other tobacco products, cannabis or alcohol consumption in the previous year, and externalizing and internalizing problems’ scores were significantly associated with the CSM measures.

Conclusions

Overall, the study findings showed that some adolescents had a likelihood of persistent smoking post-initiation, irrespective of baseline electronic cigarette usage. In the study, four percent of cigarette-naive adolescents initiated smoking cigarettes, and 2.50% continued smoking in three years. The aOR values indicated a positive association between electronic cigarette usage and subsequent cigarette smoking.

On the contrary, given the low prevalence of smoking, the risks of persistent smoking, in absolute terms, for individuals who used and didn’t use electronic cigarettes, and the difference in smoking risks between the two groups were minor.

Therefore, the alteration in the prevalence of cigarette smoking due to electronic cigarette usage at the national level was minimal. Few adolescents are likely to continue smoking after initiation, regardless of e-cigarette use.