Table 2.
Unadjusted relative risk ratios for changes in susceptibility and smoking status in relation to explanatory variables.
| Among non‐susceptible never smokers at baseline | Among susceptible never smokers at baseline | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| RRR of becoming susceptible | RRR of becoming an ever smoker | RRR of becoming non‐susceptible | RRR of becoming an ever smoker | |||||||||
| Estimate | 99% CI | P | Estimate | 99% CI | P | Estimate | 99% CI | P | Estimate | 99% CI | P | |
| Sex | ||||||||||||
| Boy | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| Girl | 1.12 | 0.87–1.43 | 0.242 | 1.47 | 0.89–2.45 | 0.049 | 0.53 | 0.23–1.25 | 0.056 | 1.45 | 1.16–1.81 | <0.001 |
| Age (years) | ||||||||||||
| 11 | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| 12 | 1.10 | 0.51–1.96 | 0.985 | 1.81 | 0.42–7.84 | 0.296 | 0.49 | 0.20–1.22 | 0.043 | 0.38 | 0.16–0.90 | 0.004 |
| 13 | 1.32 | 0.66–2.65 | 0.304 | 4.12 | 1.71–9.97 | <0.001 | 0.26 | 0.11–0.60 | 0.000 | 0.54 | 0.23–1.24 | 0.057 |
| 14 | 1.11 | 0.55–2.26 | 0.697 | 4.64 | 1.49–14.5 | 0.001 | 0.55 | 0.28–1.08 | 0.023 | 1.26 | 0.40–3.96 | 0.610 |
| 15 | 0.52 | 0.15–1.80 | 0.174 | 8.51 | 2.18–33.1 | <0.001 | 0.39 | 0.15–1.01 | 0.011 | 0.67 | 0.32–1.42 | 0.172 |
| Quintile of index of multiple deprivation | ||||||||||||
| 1 (least deprived) | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| 2 | 1.10 | 0.60–2.02 | 0.686 | 1.31 | 0.46–3.77 | 0.507 | 0.42 | 0.21–0.81 | 0.001 | 0.98 | 0.51–1.90 | 0.946 |
| 3 | 1.08 | 0.59–1.99 | 0.736 | 1.33 | 0.68–2.59 | 0.279 | 1.01 | 0.48–2.12 | 0.965 | 0.94 | 0.42–2.13 | 0.854 |
| 4 | 0.79 | 0.43–1.45 | 0.326 | 0.70 | 0.25–1.95 | 0.373 | 0.91 | 0.24–3.43 | 0.852 | 1.43 | 0.27–7.68 | 0.581 |
| 5 (most deprived) | 1.16 | 0.60–2.22 | 0.564 | 1.28 | 0.53–3.14 | 0.471 | 0.58 | 0.17–2.00 | 0.258 | 1.15 | 0.58–2.25 | 0.602 |
| Parental smoking | ||||||||||||
| Neither parent smokes | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| One parent smokes | 1.57 | 1.08–2.20 | 0.002 | 2.62 | 0.94–7.26 | 0.015 | 1.48 | 0.86–2.55 | 0.060 | 1.63 | 0.98–2.70 | 0.013 |
| Both parents smoke | 1.10 | 0.49–2.45 | 0.771 | 3.33 | 1.37–8.11 | <0.001 | 1.08 | 0.37–3.15 | 0.846 | 2.48 | 0.90–6.85 | 0.022 |
| Sibling smoking | ||||||||||||
| None smokes | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| At least one smokes | 1.76 | 0.74–4.14 | 0.091 | 1.54 | 0.58–4.08 | 0.256 | 1.10 | 0.60–2.03 | 0.682 | 1.83 | 0.94–3.57 | 0.019 |
| Smoking in the main family home | ||||||||||||
| Not allowed | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| Allowed | 1.49 | 0.91–2.45 | 0.037 | 2.50 | 1.34–4.65 | <0.001 | 1.06 | 0.42–2.68 | 0.860 | 1.47 | 0.70–3.08 | 0.181 |
| Number of friends who smoke | ||||||||||||
| None | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| One or two | 1.61 | 0.85–3.07 | 0.055 | 1.94 | 0.61–6.13 | 0.139 | 0.62 | 0.22–1.76 | 0.234 | 1.45 | 0.92–2.30 | 0.037 |
| Three or more | 1.66 | 1.40–1.96 | <0.001 | 4.50 | 1.40–14.5 | 0.001 | 0.56 | 0.33–0.96 | 0.005 | 2.33 | 1.33–4.07 | <0.001 |
| Not sure | 1.94 | 1.34–2.83 | <0.001 | 3.65 | 1.50–8.90 | <0.001 | 0.89 | 0.39–2.02 | 0.705 | 1.79 | 1.22–2.62 | <0.001 |
| Self‐perceived academic performance | ||||||||||||
| Excellent or good | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| Average or below average | 1.84 | 1.16–2.92 | 0.001 | 2.25 | 1.20–4.21 | 0.001 | 0.72 | 0.26–1.94 | 0.389 | 0.92 | 0.39–2.15 | <0.001 |
| Rebelliousness | ||||||||||||
| Low | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| High | 1.60 | 1.09–2.33 | 0.001 | 2.58 | 1.52–4.35 | <0.001 | 1.17 | 0.71–1.95 | 0.419 | 1.33 | 0.78–2.26 | 0.164 |
| Noticing point‐of‐sale displays | ||||||||||||
| Sometimes or less | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| Most or every time | 1.80 | 1.12–2.88 | 0.001 | 2.15 | 0.96–4.82 | 0.014 | 2.10 | 0.78–5.64 | 0.053 | 1.17 | 0.47–2.93 | 0.664 |
| Frequency of visiting shops | ||||||||||||
| Fewer than 2 or 3 times a week | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| At least 2 or 3 times a week | 1.52 | 1.16–1.99 | <0.001 | 1.75 | 0.91–3.34 | 0.026 | 1.20 | 0.64–2.23 | 0.461 | 1.49 | 0.88–2.52 | 0.053 |
| Number of brands recognized | ||||||||||||
| None | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| 1–5 | 1.92 | 1.25–2.94 | <0.001 | 1.60 | 1.06–2.40 | 0.003 | 0.88 | 0.36–2.14 | 0.715 | 1.22 | 0.70–2.15 | 0.357 |
| More than 5 | 2.31 | 1.62–3.29 | <0.001 | 2.93 | 1.88–4.57 | <0.001 | 0.91 | 0.48–1.73 | 0.700 | 1.96 | 1.19–3.23 | 0.001 |
| Missing | 2.81 | 1.78–4.43 | <0.001 | 1.35 | 0.48–3.81 | 0.453 | 1.27 | 0.34–4.67 | 0.641 | 1.56 | 0.47–5.20 | 0.342 |
| Combined frequency of visiting and noticing displays | ||||||||||||
| Visit <2/3 times per week/notice sometimes or less | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| Visit <2/3 times per week/notice most or every time | 2.72 | 1.32–5.58 | <0.001 | 1.95 | 0.33–11.5 | 0.331 | 1.83 | 0.47–7.07 | 0.250 | 0.66 | 0.21–2.09 | 0.350 |
| Visit >2/3 times per week/notice sometimes or less | 2.71 | 1.20–6.09 | 0.002 | 1.58 | 0.21–11.6 | 0.555 | 0.90 | 0.13–6.42 | 0.888 | 0.75 | 0.21–2.61 | 0.550 |
| Visit >2/3 times per week/notice most or every time | 3.53 | 1.69–7.38 | <0.001 | 3.25 | 0.74–14.2 | 0.040 | 2.07 | 0.41–1.04 | 0.244 | 1.18 | 0.37–3.84 | 0.710 |
| Combined frequency of noticing displays and brand recognition | ||||||||||||
| Notice sometimes or less/0 brands | 1.00 | 1.00 | 1.00 | 1.00 | ||||||||
| Notice sometimes or less/1–5 brands | 2.05 | 0.82–5.16 | 0.045 | 1.53 | 0.20–11.8 | 0.590 | 0.88 | 0.13–5.73 | 0.855 | 1.05 | 0.38–2.88 | 0.901 |
| Notice sometimes or less/6+ brands | 2.53 | 0.67–9.51 | 0.072 | 1.53 | 0.11–22.3 | 0.681 | * | 1.26 | 0.16–9.80 | 0.772 | ||
| Notice most or every time/0 brands | 1.76 | 0.63–4.88 | 0.155 | 1.66 | 0.45–6.12 | 0.321 | 2.84 | 0.70–11.6 | 0.055 | 0.92 | 0.25–3.43 | 0.868 |
| Notice most or every time/1–5 brands | 2.93 | 1.06–8.09 | 0.006 | 2.37 | 0.81–6.92 | 0.037 | 2.01 | 0.51–7.88 | 0.187 | 1.18 | 0.29–4.85 | 0.761 |
| Notice most or every time/6+ brands | 3.47 | 1.29–9.33 | 0.001 | 4.34 | 1.66–11.4 | <0.001 | 2.09 | 0.58–7.46 | 0.137 | 1.92 | 0.59–6.19 | 0.153 |
| Missing | 4.20 | 1.40–12.6 | 0.001 | 1.90 | 0.70–5.17 | 0.098 | 2.68 | 0.63–11.4 | 0.080 | 1.48 | 0.32–6.90 | 0.510 |
*
Could not estimate due to small numbers. RRR = relative risk ratio; CI = confidence interval.