Characteristic (at baseline) | No. (%) within category who initiated daily smoking by follow-up | OR (95% CI) | |
---|---|---|---|
Unadjusted† | Adjusted‡ | ||
Age, yr | |||
≤ 14 | 204/6179 (3.3) | 1.0 (ref) | 1.0 (ref) |
15 | 219/6298 (3.5) | 1.04 (0.86–1.27) | 0.74 (0.60–0.92) |
16 | 206/4997 (4.1) | 1.27 (1.04–1.55) | 0.70 (0.55–0.88) |
≥ 17§ | 58/1217 (4.8) | 1.46 (1.07–1.98) | 0.73 (0.51–1.03) |
Sex | |||
Female | 320/9996 (3.2) | 1.0 (ref) | 1.0 (ref) |
Male | 367/8695 (4.2) | 1.36 (1.17–1.59) | 1.36 (1.15–1.62) |
Race/ethnicity¶ | |||
White | 525/14 488 (3.6) | 1.0 (ref) | 1.0 (ref) |
Black | 21/585 (3.6) | 1.23 (0.78–1.94) | 1.30 (0.78–2.15) |
Asian | 11/965 (1.1) | 0.38 (0.21–0.70) | 0.45 (0.24–0.85) |
Aboriginal | 43/406 (10.6) | 2.49 (1.75–3.54) | 1.42 (0.96–2.09) |
Latin American/Hispanic | 11/296 (3.7) | 1.21 (0.65–2.23) | 1.03 (0.54–1.98) |
Other/mixed | 75/1876 (4.0) | 1.21 (0.94–1.56) | 1.09 (0.82–1.43) |
Spending money, $ | |||
0 | 95/3513 (2.7) | 1.0 (ref) | 1.0 (ref) |
1–20 | 219/6436 (3.4) | 1.26 (0.99–1.62) | 1.07 (0.81–1.39) |
21–100 | 182/4480 (4.1) | 1.49 (1.15–1.92) | 1.03 (0.78–1.36) |
> 100 | 109/1731 (6.3) | 2.24 (1.69–2.99) | 1.16 (0.84–1.60) |
Don’t know/not stated | 82/2531 (3.2) | 1.20 (0.89–1.62) | 1.15 (0.83–1.60) |
Smoking status | |||
Never tried, not susceptible | 83/11 075 (0.7) | 1.0 (ref) | 1.0 (ref) |
Never tried, susceptible | 129/4719 (2.7) | 3.69 (2.79–4.87) | 3.58 (2.70–4.73) |
Puffer | 106/1514 (7.0) | 9.81 (7.31–13.16) | 9.33 (6.91–12.59) |
Experimental smoker | 308/1274 (24.2) | 40.80 (31.65–52.60) | 37.73 (28.91–49.25) |
Former smoker | 13/29 (44.8) | 96.81 (44.52–210.49) | 94.99 (43.19–208.92) |
Current occasional smoker | 48/80 (60.0) | 193.01 (116.72–319.16) | 157.54 (93.59–265.19) |
Past 30-day e-cigarette use | |||
No | 551/17 911 (3.1) | 1.0 (ref) | 1.0 (ref) |
Yes | 136/780 (17.4) | 6.97 (5.65–8.60) | 1.79 (1.41–2.28) |
Note: CI = confidence interval, OR = odds ratio.
↵* Among those who had never smoked every day for 7 days at baseline, but had smoked every day for 7 days at follow-up; n = 619 had already initiated daily smoking at baseline and were excluded from this measure.
↵† From separate generalized linear mixed models for initiating daily smoking between waves, including only the listed covariable, with school as a random effect (n = 18 691 for all models except race/ethnicity; n = 18 616 for race/ethnicity model).
↵‡ From a generalized linear mixed model for initiating daily smoking between waves, including the covariables in the table, with school (n = 86) as a random effect (n = 18 616).
↵§ Categories for age 17 and age ≥ 18 were combined because of low numbers for the latter category (n = 5).
↵¶ Information on race/ethnicity was missing for 75 participants; these were excluded from the multivariable model.