Table 4 Associations of wave 1 cigarette/e-cigarette use state with wave 2 state: adjusted odds ratio* (aOR) with 95% confidence interval (CI)

Model A¹. Exclusive cigarette smoker group (n = 8613)

1.2. Established cigarette smoker without a history of e-cigarette use

4.04^‡ (2.19, 7.45)

4.34^‡ (1.87, 10.10)

1 [Reference]

0.52^† (0.28, 0.97)

1.3. Established cigarette smoker with a history of e-cigarette use

1.60 (0.68, 3.74)

9.73^‡ (3.39, 27.92)

1 [Reference]

0.14^‡ (0.05, 0.39)

Model B². Exclusive e-cigarette user group (n = 580)

2.2. Experimental e-cigarette user with a history of cigarette smoking

5.36 (0.82, 35.14)

2.63 (0.22, 31.62)

1 [Reference]

0.55 (0.16, 1.87)

2.3. Established e-cigarette user without a history of cigarette smoking

0.13^† (0.02, 0.87)

0.53 (0.05, 6.25)

1 [Reference]

0.05^‡ (0.02, 0.17)

2.4. Established e-cigarette user with a history of cigarette smoking

0.27 (0.07, 1.06)

2.03 (0.30, 13.84)

1 [Reference]

0.02^‡ (0.01, 0.06)

Model C³. Dual user group (n = 2132)

3.2. Established dual user

0.30^‡ (0.20, 0.46)

2.43^‡ (1.59, 3.73)

1 [Reference]

0.31^‡ (0.19, 0.51)