Background
Methods
Study population
Study cohort, %a
| Subjects lost, %a
|
pvalueb
| |
---|---|---|---|
(n = 1135) | (n = 946) | ||
Individual characteristics | |||
Ultimate | |||
Sex | .03 | ||
Female | 51 | 46 | |
Age, years | .26 | ||
10 | 50 | 53 | |
11 | 50 | 47 | |
Anxiety, mean (SE)c
| 3.4 (0.1) | 3.7 (0.1) | .02 |
Distal
| |||
Self-esteem, mean (SE)d
| 13.7 (0.1) | 13.3 (0.1) | <.001 |
Academic performance | .56 | ||
Poor/very poor | 2 | 1 | |
Average | 18 | 19 | |
Well | 46 | 46 | |
Very well | 34 | 34 | |
Social characteristics
| |||
Ultimate
| |||
Family structure | .005 | ||
2 parents | 84 | 79 | |
1 parent | 16 | 21 | |
PMK Education | <.001 | ||
Low (< 12 years of school) | 19 | 28 | |
High (≥12 years of school) | 81 | 73 | |
Annual household income, CAN $ | <.001 | ||
< 30,000 | 15 | 21 | |
30,000-59,999 | 31 | 40 | |
60,000-89,999 | 31 | 23 | |
≥ 90,000 | 23 | 16 | |
Distal
| |||
PMK smoking status | .03 | ||
Tobacco smoker | 26 | 30 | |
PMK drinking status | .61 | ||
Alcohol drinker | 28 | 27 | |
Parent-child relationship, mean (SE)e
| 22.9 (0.2) | 22.3 (0.2) | .005 |
Peer smoking | .94 | ||
No peers | 95 | 96 | |
A few peers | 4 | 3 | |
Most/all peers | 1 | 1 | |
Peer drinking | .05 | ||
No peers | 97 | 95 | |
A few peers | 2 | 4 | |
Most/all peers | 1 | 1 | |
Peer-child relationship, mean (SE)f
| 12.8 (0.1) | 12.8 (0.1) | .86 |
Lifestyle risk factors
| |||
Physical inactivityg
| 50 | 54 | .09 |
Sedentary behaviorh
| 42 | 46 | .11 |
Ever smokingi
| 6 | 7 | .60 |
Ever drinkingj
| 6 | 10 | .005 |
High body mass indexk
| 23 | 29 | .004 |
Data collection
Measures
Risk factors
Independent variables
Statistical analyses
Results
Descriptive findings
Time 1a
| Time 2a
| Time 3a
| ||||||
---|---|---|---|---|---|---|---|---|
(n = 1135) | (n = 1135) | (n = 1135) |
p
| |||||
%b
| 95% CIc
| %b
| 95% CIc
| %b
| 95% CIc
| for trendd
| ||
Risk factors
| ||||||||
Physical inactivitye
| Male | 43 | 36, 49 | 44 | 37, 50 | 61 | 55, 67 | <.001 |
Female | 57 | 50, 64 | 59 | 52, 65 | 72 | 65, 78 | .002 | |
Sedentary behaviorf
| Male | 49 | 42, 55 | 43 | 37, 50 | 50 | 44, 56 | .78 |
Female | 36 | 30, 42 | 36 | 30, 43 | 36 | 29, 42 | .99 | |
Ever smokingg
| Male | 6 | 3, 11 | 12 | 9, 17 | 31 | 26, 38 | <.001 |
Female | 6 | 3, 10 | 15 | 11, 20 | 29 | 24, 36 | <.001 | |
Ever drinkingh
| Male | 7 | 4, 11 | 16 | 12, 22 | 48 | 41, 54 | <.001 |
Female | 5 | 3, 9 | 14 | 10, 18 | 48 | 41, 55 | <.001 | |
High body mass indexi
| Male | 24 | 19, 30 | 23 | 17, 30 | 18 | 13, 23 | .07 |
Female | 22 | 17, 29 | 15 | 11, 19 | 14 | 10, 18 | .05 | |
No. of Risk factors
| ||||||||
0 | Male | 31 | 25, 37 | 21 | 17, 26 | 6 | 4, 11 | <.001 |
Female | 26 | 21, 32 | 22 | 17, 28 | 10 | 6, 16 | <.001 | |
1 | Male | 38 | 32, 44 | 40 | 34, 47 | 27 | 22, 32 | .003 |
Female | 44 | 37, 50 | 39 | 33, 47 | 31 | 24, 38 | .01 | |
2 | Male | 24 | 19, 30 | 27 | 22, 33 | 37 | 31, 43 | .002 |
Female | 24 | 19, 29 | 25 | 18, 32 | 27 | 21, 34 | .42 | |
3-5 | Male | 7 | 5, 11 | 12 | 8, 16 | 30 | 25, 36 | <.001 |
Female | 6 | 4, 11 | 14 | 10, 19 | 32 | 27, 38 | <.001 |
Longitudinal Poisson regression models
Rate ratiob 95% CIc
| Rate ratiob 95% CIc
| Rate ratiob 95% CIc
| |||||||
---|---|---|---|---|---|---|---|---|---|
Model 1 | Model 2 | Model 3 | |||||||
Individual characteristics | Individual characteristics | Individual characteristics | |||||||
Ultimate | Distal | Ultimate | |||||||
Sex | Self-esteemf
| 0.97 | 0.97, 0.98 | Sex | |||||
Female | 1 | Referent | Academic performance | Female | 1 | Referent | |||
Male | 1.01 | 0.96, 1.06 | Poor/very poor | 1 | Referent | Male | 1.00 | 0.95, 1.05 | |
Age, yearsd
| Average | 0.93 | 0.85, 1.01 | Age, yearsd
| |||||
10 | 1 | Referent | Well | 0.88 | 0.80, 0.96 | 10 | 1 | Referent | |
11 | 1.08 | 1.02, 1.15 | Very well | 0.88 | 0.79, 0.97 | 11 | 1.07 | 1.01, 1.13 | |
Anxietye
| 1.02 | 1.01, 1.03 | Time | Anxietye
| 1.01 | 1.00, 1.02 | |||
Time | 1 (Cycle 4) | 1 | Referent |
Distal
| |||||
1 (Cycle 4) | 1 | Referent | 2 (Cycle 5) | 1.08 | 1.03, 1.14 | Self-esteemf
| 0.98 | 0.97, 0.98 | |
2 (Cycle 5) | 1.11 | 1.06, 1.17 | 3 (Cycle 6) | 1.37 | 1.30, 1.44 | Academic performance | |||
3 (Cycle 6) | 1.43 | 1.35, 1.50 | Intercept | 3.38 | 3.00, 3.81 | Poor/very poor | 1 | Referent | |
Intercept | 1.89 | 1.78, 2.01 | Average | 0.93 | 0.85, 1.01 | ||||
Well | 0.88 | 0.80, 0.97 | |||||||
Very well | 0.88 | 0.79, 0.98 | |||||||
Time | |||||||||
1 (Cycle 4) | 1 | Referent | |||||||
2 (Cycle 5) | 1.09 | 1.03, 1.14 | |||||||
3 (Cycle 6) | 1.37 | 1.30, 1.44 | |||||||
Intercept | 3.09 | 2.66, 3.60 | |||||||
-2 Log Lg
| 1335.42 | 1294.37 | 1285.03 | ||||||
Log L ratioh
| 35.90*** | 76.94*** | 86.28*** | ||||||
DF | 3 | 4 | 7 |
Rate ratiob 95% CIc
| Rate ratiob 95% CIc
| Rate ratiob 95% CIc
| |||||||
---|---|---|---|---|---|---|---|---|---|
Model 1 | Model 2 | Model 3 | |||||||
Social characteristics | Social characteristics | Social characteristics | |||||||
Ultimate | Distal | Ultimate | |||||||
Family structure | PMK smoking status | Family structure | |||||||
2 parents | 1 | Referent | Nonsmoker | 1 | Referent | 2 parents | 1 | Referent | |
1 parent | 1.07 | 0.98, 1.17 | Smoker | 1.10 | 1.05, 1.15 | 1 parent | 1.05 | 0.97, 1.12 | |
PMK Education | PMK drinking status | PMK Education | |||||||
Low (< 12 years of school) | 1 | Referent | Nondrinker | 1 | Referent | Low (< 12 years of school) | 1 | Referent | |
High (≥l2 years of school) | 0.94 | 0.88, 1.01 | Drinker | 1.01 | 0.97, 1.06 | High (≥l2 years of school) | 0.98 | 0.92, 1.04 | |
Annual household income | Parent-child relationshipd
| 0.99 | 0.99, 1.00 | Annual household income | |||||
< CAN$30,000 | 1 | Referent | Peer smoking | < CAN$30,000 | 1 | Referent | |||
CAN$30,000 -59,999 | 1.01 | 0.94, 1.09 | No peers | 1 | Referent | CAN$30,000 -59,999 | 1.01 | 0.94, 1.08 | |
CAN$60,000 -89,999 | 1.07 | 0.98, 1.16 | A few peers | 1.14 | 1.06, 1.22 | CAN$60,000 -89,999 | 1.09 | 1.00, 1.17 | |
≥CAN$90,000 | 1.03 | 0.93, 1.13 | Most/All peers | 1.41 | 1.27, 1.56 | ≥CAN$90,000 | 1.04 | 0.96, 1.14 | |
Time | Peer drinking |
Distal
| |||||||
1 (Cycle 4) | 1 | Referent | No peers | 1 | Referent | PMK smoking status | |||
2 (Cycle 5) | 1.10 | 1.05, 1.16 | A few peers | 1.13 | 1.06, 1.21 | Nonsmoker | 1 | Referent | |
3 (Cycle 6) | 1.41 | 1.34, 1.49 | Most/All peers | 1.26 | 1.17, 1.37 | Smoker | 1.10 | 1.05, 1.15 | |
Intercept | 2.10 | 1.94, 2.29 | Peer-child relationshipe
| 0.99 | 0.98, 1.00 | PMK drinking status | |||
Time | Nondrinker | 1 | Referent | ||||||
1 (Cycle 4) | 1 | Referent | Drinker | 1.01 | 0.97, 1.05 | ||||
2 (Cycle 5) | 1.06 | 1.01, 1.11 | Parent-child relationshipd
| 0.99 | 0.99, 1.00 | ||||
3 (Cycle 6) | 1.16 | 1.09, 1.24 | Peer smoking | ||||||
Intercept | 2.75 | 2.45, 3.08 | No peers | 1 | Referent | ||||
A few peers | 1.14 | 1.06, 1.22 | |||||||
Most/All peers | 1.41 | 1.27, 1.57 | |||||||
Peer drinking | |||||||||
No peers | 1 | Referent | |||||||
A few peers | 1.13 | 1.06, 1.21 | |||||||
Most/All peers | 1.26 | 1.17, 1.36 | |||||||
Peer-child relationshipe
| 0.99 | 0.98, 1.00 | |||||||
Time | |||||||||
1 (Cycle 4) | 1 | Referent | |||||||
2 (Cycle 5) | 1.05 | 1.00, 1.11 | |||||||
3 (Cycle 6) | 1.15 | 1.08, 1.23 | |||||||
Intercept | 2.71 | 2.39, 3.07 | |||||||
-2 Log Lf
| 1349.28 | 1117.23 | 1107.07 | ||||||
Log L ratiog
| 22.03*** | 254.07*** | 264.24*** | ||||||
DF | 5 | 8 | 13 |
Rate ratiob 95% CIc
| Rate ratiob 95% CIc
| Rate ratiob 95% CIc
| Rate ratiob 95% CIc
| |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Model 1 | Model 2 | Model 3 | Model 4 | |||||||||
Individual characteristics | Individual characteristics | Individual characteristics | Individual characteristics | |||||||||
Distal | Distal | Distal | Distal | |||||||||
Self-esteemd
| 0.97 | 0.97, 0.98 | Self-esteemd
| 0.98 | 0.97, 0.98 | Self-esteemd
| 0.98 | 0.98, 0.99 | Self-esteemd
| 0.98 | 0.98, 0.99 | |
Academic performance | Academic performance | Academic performance | Academic performance | |||||||||
Poor/very poor | 1 | Referent | Poor/very poor | 1 | Referent | Poor/very poor | 1 | Referent | Poor/very poor | 1 | Referent | |
Average | 0.93 | 0.85, 1.01 | Average | 0.93 | 0.85, 1.01 | Average | 0.98 | 0.88, 1.09 | Average | 0.98 | 0.88, 1.09 | |
Well | 0.88 | 0.80, 0.96 | Well | 0.88 | 0.80, 0.97 | Well | 0.94 | 0.84, 1.05 | Well | 0.94 | 0.84, 1.04 | |
Very well | 0.88 | 0.79, 0.97 | Very well | 0.88 | 0.79, 0.98 | Very well | 0.96 | 0.86, 1.08 | Very well | 0.96 | 0.85, 1.08 | |
Time |
Ultimate
|
Ultimate
|
Ultimate
| |||||||||
1 (Cycle 4) | 1 | Referent | Sex | Sex | Sex | |||||||
2 (Cycle 5) | 1.08 | 1.03, 1.14 | Female | 1 | Referent | Female | 1 | Referent | Female | 1 | Referent | |
3 (Cycle 6) | 1.37 | 1.30, 1.44 | Male | 1.00 | 0.95, 1.05 | Male | 1.01 | 0.97, 1.05 | Male | 1.01 | 0.97, 1.05 | |
Intercept | 3.38 | 3.00, 3.81 | Age, yearse
| Age, yearse
| Age, yearse
| |||||||
10 | 1 | Referent | 10 | 1 | Referent | 10 | 1 | Referent | ||||
11 | 1.07 | 1.01, 1.13 | 11 | 1.01 | 0.96, 1.06 | 11 | 1.01 | 0.96, 1.06 | ||||
Anxietyf
| 1.01 | 1.00, 1.02 | Anxietyf
| 1.00 | 0.99, 1.01 | Anxietyf
| 1.01 | 1.00, 1.01 | ||||
Time |
Social characteristics
|
Social characteristics
| ||||||||||
1 (Cycle 4) | 1 | Referent |
Distal
|
Distal
| ||||||||
2 (Cycle 5) | 1.09 | 1.03, 1.14 | PMK smoking status | PMK smoking status | ||||||||
3 (Cycle 6) | 1.37 | 1.30, 1.44 | Nonsmoker | 1 | Referent | Nonsmoker | 1 | Referent | ||||
Intercept | 3.09 | 2.66, 3.60 | Smoker | 1.10 | 1.05, 1.16 | Smoker | 1.11 | 1.05, 1.16 | ||||
PMK drinking status | PMK drinking status | |||||||||||
Nondrinker | 1 | Referent | Nondrinker | 1 | Referent | |||||||
Drinker | 1.01 | 0.97, 1.06 | Drinker | 1.01 | 0.97, 1.05 | |||||||
Parent-child relationshipg
| 1.00 | 0.99, 1.00 | Parent-child relationshipg
| 1.00 | 0.99, 1.00 | |||||||
Peer smoking | Peer smoking | |||||||||||
No peers | 1 | Referent | No peers | 1 | Referent | |||||||
A few peers | 1.13 | 1.06, 1.21 | A few peers | 1.14 | 1.07, 1.22 | |||||||
Most/All peers | 1.40 | 1.27, 1.54 | Most/All peers | 1.41 | 1.28, 1.55 | |||||||
Peer drinking | Peer drinking | |||||||||||
No peers | 1 | Referent | No peers | 1 | Referent | |||||||
A few peers | 1.12 | 1.05, 1.20 | A few peers | 1.12 | 1.04, 1.19 | |||||||
Most/All peers | 1.24 | 1.15, 1.35 | Most/All peers | 1.23 | 1.14, 1.34 | |||||||
Peer-child relationshiph
| 1.00 | 0.99, 1.00 | Peer-child relationshiph
| 0.99 | 0.99, 1.00 | |||||||
Time |
Social characteristics
| |||||||||||
1 (Cycle 4) | 1 | Referent |
Ultimate
| |||||||||
2 (Cycle 5) | 1.05 | 0.99, 1.10 | Family structure | |||||||||
3 (Cycle 6) | 1.15 | 1.08, 1.23 | 2 parents | 1 | Referent | |||||||
Intercept | 3.04 | 2.60, 3.35 | 1 parent | 1.04 | 0.97, 1.12 | |||||||
PMK Education | ||||||||||||
Low (< 12 years of school) | 1 | Referent | ||||||||||
High (≥l2 years of school) | 0.99 | 0.94, 1.05 | ||||||||||
Annual household income | ||||||||||||
< CAN$30,000 | 1 | Referent | ||||||||||
CAN$30,000- 59,999 | 1.00 | 0.94. 1.08 | ||||||||||
CAN$60,000- 89,999 | 1.09 | 1.00, 1.17 | ||||||||||
≥CAN$90,000 | 1.04 | 0.96, 1.12 | ||||||||||
Time | ||||||||||||
1 (Cycle 4) | 1 | Referent | ||||||||||
2 (Cycle 5) | 1.04 | 0.99, 1.10 | ||||||||||
3 (Cycle 6) | 1.15 | 1.08, 1.22 | ||||||||||
Intercept | 2.95 | 2.49, 3.50 | ||||||||||
-2 Log Li
| 1294.37 | 1285.03 | 1097.17 | 1086.24 | ||||||||
Log L ratioj
| 76.94*** | 9.34** | 187.86*** | 10.93* | ||||||||
DF | 4 | 3 | 8 | 5 |