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-value	OR (95% CI)	p-value	OR (95% CI)	p-value
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)	<0.001	2.07 (1.41, 3.04)	<0.001	1.57 (0.99, 2.49)	0.05
E-cigarette Never	646	9.7	reference		reference		reference
E-cigarette Former	406	18.6	2.13 (1.43, 3.18)	<0.001	2.04 (1.33, 3.12)	0.001	1.55 (0.94, 2.56)	0.09
E-cigarette Past 30-Days	171	21.5	2.56 (1.58, 4.14)	<0.001	2.22 (1.31, 3.74)	0.003	1.69 (0.93, 3.05)	0.08
Outcome: Smoked during Past 30 Days
Wave 1 Predictors
E-cigarette Never	699	26.6	reference		reference		reference
E-cigarette Ever	596	38.8	1.75 (1.35, 2.27)	<0.001	1.65 (1.26, 2.15)	<0.001	1.32 (0.99, 1.76)	0.06
E-cigarette Never	699	26.6	reference		reference		reference
E-cigarette Former	415	36.1	1.56 (1.15, 2.12)	0.004	1.48 (1.09, 2.02)	0.01	1.20 (0.86, 1.68)	0.29
E-cigarette Past 30-Days	176	45.3	2.29 (1.64, 3.19)	<0.001	2.10 (1.47, 2.99)	<0.001	1.64 (1.12, 2.41)	0.01
Outcome: Smoked 100 Cigarettes and Smoked during Past 30 Days
Wave 1 Predictors
E-cigarette Never	644	7.1	reference		reference		reference
E-cigarette Ever	580	15.6	2.43 (1.55, 3.80)	<0.001	2.23 (1.39, 3.59)	<0.001	1.80 (1.04, 3.12)	0.03
E-cigarette Never	644	7.1	reference		reference		reference
E-cigarette Former	406	15.5	2.41 (1.46, 3.97)	<0.001	2.29 (1.35, 3.89)	0.002	1.85 (1.02, 3.36)	0.04
E-cigarette Past 30-Days	171	16.3	2.56 (1.52, 4.32)	<0.001	2.19 (1.24, 3.88)	0.007	1.76 (0.92, 3.37)	0.09

^a. Model covariates include: gender, age, and race/ethnicity.

^b. Model covariates additionally include: 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.

Abbreviations: CI = confidence interval; OR = odds ratio

Odds ratios and confidence intervals corresponding to model covariates are shown in Supplemental Table 1.