TABLE 2

E-cigarette Use and Risk of Subsequent Smoking Among Baseline Never Smokers

E-cigarette Use (Baseline)Cigarette Use (Follow-up)
NeverExperimentationaInfrequentbFrequentc
Total, N (%) 4575 (90.8)315 (6.2)96 (1.9)55 (1.1)
 Never3891 (93.3)184 (4.4)60 (1.4)36 (0.9)
 Ever673 (78.5)129 (15.1)36 (4.2)19 (2.2)
Versus never use, adjusted OR (95% CI)dReference4.57 (3.56–5.87)4.27 (2.75–6.62)3.51 (1.97–6.24)
Versus previous use, adjusted OR (95% CI)eReference0.98 (0.60–1.60)0.76 (0.41–1.42)
  • —, not applicable.

  • a Experimentation is initiation between baseline and follow-up but no use in the past 30 days.

  • b Infrequent use is initiation and use on 1–2 of the past 30 days.

  • c Frequent use is initiation and use on 3–5 or more of the past 30 days.

  • d Adjusted for sex, race and/or ethnicity, grade, and study; restricted to never cigarette users at baseline with a random effect for school.

  • e Additionally restricted to ever cigarette initiators.