TABLE 1.

Progression From Cigarette Experimentation to Established Smoking, According to Baseline E-cigarette Use

	n	Weighted % With Outcome	Unadjusted		Adjusteda		Adjustedb
			OR (95% CI)	P	OR (95% CI)	P	OR (95% CI)	P
Outcome: smoked 100 cigarettes
Wave 1 predictors
E-cigarette never	646	9.7	Reference	—	Reference	—	Reference	—
E-cigarette ever	582	19.3	2.23 (1.55–3.21)	<.001	2.07 (1.41–3.04)	<.001	1.57 (0.99–2.49)	.05
E-cigarette never	646	9.7	Reference	—	Reference	—	Reference	—
E-cigarette former	406	18.6	2.13 (1.43–3.18)	<.001	2.04 (1.33–3.12)	.001	1.55 (0.94–2.56)	.09
E-cigarette in the past 30 d	171	21.5	2.56 (1.58–4.14)	<.001	2.22 (1.31–3.74)	.003	1.69 (0.93–3.05)	.08
Outcome: smoked during the past 30 d
Wave 1 predictors
E-cigarette never	699	26.6	Reference	—	Reference	—	Reference	—
E-cigarette ever	596	38.8	1.75 (1.35–2.27)	<.001	1.65 (1.26–2.15)	<.001	1.32 (0.99–1.76)	.06
E-cigarette never	699	26.6	Reference	—	Reference	—	Reference	—
E-cigarette former	415	36.1	1.56 (1.15–2.12)	.004	1.48 (1.09–2.02)	.01	1.20 (0.86–1.68)	.29
E-cigarette in the past 30 d	176	45.3	2.29 (1.64–3.19)	<.001	2.10 (1.47–2.99)	<.001	1.64 (1.12–2.41)	.01
Outcome: smoked 100 cigarettes and smoked during the past 30 d
Wave 1 predictors
E-cigarette never	644	7.1	Reference	—	Reference	—	Reference	—
E-cigarette ever	580	15.6	2.43 (1.55–3.80)	<.001	2.23 (1.39–3.59)	<.001	1.80 (1.04–3.12)	.03
E-cigarette never	644	7.1	Reference	—	Reference	—	Reference	—
E-cigarette former	406	15.5	2.41 (1.46–3.97)	<.001	2.29 (1.35–3.89)	.002	1.85 (1.02–3.36)	.04
E-cigarette in the past 30 d	171	16.3	2.56 (1.52–4.32)	<.001	2.19 (1.24–3.88)	.007	1.76 (0.92–3.37)	.09

ORs and CIs corresponding to model covariates are shown in Supplemental Table 2. —, not applicable.

^aModel covariates include the following: sex, age, and race and/or ethnicity.

^bModel covariates additionally include the following: parent education, urban residence, household tobacco use, alcohol ever use, tobacco advertisement receptivity, sensation-seeking score, cigarette warning label exposure, interview time of year, and ever use of any other tobacco product.