Association of ever used cigarettes (left-hand panel), any recent tobacco smoking (middle panel) or regular smoker (right-hand panel) at follow-up with predictors among never users of combustible cigarettes at baseline (over 24 months; n=3994)
| Predictors | Ever smoked cigarettes | Any recent tobacco smoking | Regularly smoked cigarettes | |||
| OR (95% CI) | P value | OR (95% CI) | P value | OR (95% CI) | P value | |
| Model 1 without covariates | ||||||
| Never used e-cigarettes | 1.00 | 1.00 | 1.00 | |||
| Ever used e-cigarettes | 4.03 (3.33 to 4.88) | <0.001 | 3.38 (2.72 to 4.21) | <0.001 | 3.60 (2.35 to 5.51) | <0.001 |
| Model 2 with covariates | ||||||
| Never used e-cigarettes | 1.00 | 1.00 | 1.00 | |||
| Ever used e-cigarettes | 2.78 (2.20 to 3.51) | <0.001 | 2.17 (1.76 to 2.69) | <0.001 | 1.27 (1.17 to 1.39) | <0.001 |
| Male | 1.00 | 1.00 | 1.00 | |||
| Female | 1.41 (1.29 to 1.54) | <0.001 | 1.16 (1.08 to 1.25) | <0.001 | 1.08 (1.04 to 1.12) | <0.001 |
| Ethnicity=non-white | 1.00 | 1.00 | 1.00 | |||
| Ethnicity=white | 0.81 (0.68 to 0.98 | <0.05 | 0.59 (0.50 to 0.70) | <0.001 | 0.91 (0.85 to 0.98) | <0.05 |
| Low family affluence | 1.00 | 1.00 | 1.00 | |||
| High family affluence | 0.92 (0.83 to 1.03) | >0.05 | 0.89 (0.80 to 0.98) | <0.05 | 0.88 (0.82 to 0.93) | <0.001 |
| Free school meals=low | 1.00 | 1.00 | 1.00 | |||
| Free school meals=high | 1.12 (0.93 to 1.35) | >0.05 | 1.10 (0.97 to 1.24) | >0.05 | 1.03 (0.96 to 1.10) | >0.05 |
| Friend smokers=none | 1.00 | 1.00 | 1.00 | |||
| Friend smokers=more than none | 1.49 (1.28 to 1.72) | <0.001 | 1.53 (1.33 to 1.76) | < 0.001 | 1.03 (0.97 to 1.10) | >0.05 |
| Family smokers=none | 1.00 | 1.00 | 1.00 | |||
| Family smokers=one or more | 1.10 (0.99 to 1.22) | >0.05 | 1.07 (0.99 to 1.17) | >0.05 | 0.95 (0.91 to 1.00) | >0.05 |
| Impulsivity | 1.30 (1.26 to 1.35) | <0.001 | 1.23 (1.19 to 1.26) | <0.001 | 1.03 (1.01 to 1.05) | <0.01 |
| Intentions=low | 1.00 | 1.00 | 1.00 | |||
| Intentions=high | 1.58 (1.24 to 2.02) | <0.001 | 1.24 (1.00 to 1.54) | >0.05 | 1.12 (0.98 to 1.29) | >0.05 |
| Attitude=low | 1.00 | 1.00 | 1.00 | |||
| Attitude=high | 1.18 (1.05 to 1.33) | <0.01 | 1.21 (1.04 to 1.41) | <0.05 | 0.98 (0.92 to 1.06) | >0.05 |
| Perceived norms=low | 1.00 | 1.00 | 1.00 | |||
| Perceived norms=high | 1.02 (0.88 to 1.19) | >0.05 | 1.11 (0.93 to 1.33) | >0.05 | 1.15 (1.06 to 1.24) | <0.01 |
| Perceived behavioural control=low | 1.00 | 1.00 | 1.00 | |||
| Perceived behavioural control=high | 1.18 (1.02 to 1.37) | <0.05 | >0.05 (0.94 to 1.18) | >0.05 | 1.08 (1.02 to 1.15) | <0.01 |
| Self-efficacy=low | 1.00 | 1.00 | 1.00 | |||
| Self-efficacy=high | 1.15 (0.98 to 1.35) | >0.05 | 1.19 (0.89 to 1.40) | >0.05 | 1.01 (0.93 to 1.10) | >0.05 |
| Friends smoking × e-cigarette use | 0.74 (0.62 to 0.88) | <0.05 | 0.70 (0.53 to 0.93) | <0.01 | 0.90 (0.81 to 1.01) | >0.05 |
| Control condition | 1.00 | 1.00 | 1.00 | |||
| Intervention condition | 0.72 (0.61 to 0.86) | <0.001 | 0.86 (0.76 to 0.96) | <0.05 | 0.99 (0.93 to 1.05) | >0.05 |
Ever smoked cigarettes: model 1 without covariates, −2 log-likelihood function = −5585.3; model 2 with covariates, −2 log-likelihood function = −4915.4; any recent tobacco smoking: model 1 without covariates, −2 log-likelihood function = −5564.8; model 2 with covariates, −2 log-likelihood function = −4578.6; regularly smoked cigarettes: model 1 without covariates, −2 log-likelihood function = −5473.6; model 2 with covariates, −2 log-likelihood function = −4076.6.