Rates of multiple (3+) sexual partners in late adolescence according to substance use and associated ORs (unadjusted for other substance use) in each cohort, by gender
| 1987/1990 (‘earlier’) cohort | 1999/2003 (‘later’) cohort | p Value of interaction by cohort | |||||||||
| <3 Sexual partners | 3+ Sexual partners | OR (95% CI)* | 3+ Sexual partners | 3+ Sexual partners | OR (95% CI)* | ||||||
| N | % | N | % | N | % | N | % | ||||
| Boys | |||||||||||
| Current smoking | |||||||||||
| No | 192 | 78.0 | 87 | 50.6 | 1.00 | 161 | 77.8 | 134 | 54.5 | 1.00 | 0.371 |
| Yes | 54 | 22.0 | 85 | 49.4 | 3.43 (2.21 to 5.32) | 46 | 22.2 | 112 | 45.5 | 2.61 (1.71 to 3.97) | |
| Excessive drinking† | |||||||||||
| No | 198 | 80.5 | 88 | 51.2 | 1.00 | 158 | 76.0 | 122 | 49.6 | 1.00 | 0.414 |
| Yes | 48 | 19.5 | 84 | 48.8 | 4.79 (3.00 to 7.64) | 50 | 24.0 | 124 | 50.4 | 3.42 (2.25 to 5.20) | |
| Ever used illicit drugs | |||||||||||
| No | 174 | 70.7 | 61 | 35.5 | 1.00 | 95 | 45.9 | 59 | 24.0 | 1.00 | 0.124 |
| Yes | 72 | 29.3 | 111 | 64.5 | 4.38 (2.85 to 6.73) | 112 | 54.1 | 187 | 76.0 | 2.71 (1.80 to 4.09) | |
| Girls | |||||||||||
| Current smoking | |||||||||||
| No | 292 | 68.1 | 18 | 45.0 | 1.00 | 202 | 81.5 | 104 | 50.0 | 1.00 | 0.203 |
| Yes | 137 | 31.9 | 22 | 55.0 | 2.61 (1.34 to 5.06) | 46 | 18.5 | 104 | 50.0 | 4.29 (2.79 to 6.58) | |
| Excessive drinking† | |||||||||||
| No | 391 | 90.9 | 30 | 75.0 | 1.00 | 208 | 83.9 | 127 | 61.1 | 1.00 | 0.953 |
| Yes | 39 | 9.1 | 10 | 25.0 | 3.54 (1.57 to 7.98) | 40 | 16.1 | 81 | 38.9 | 3.55 (2.27 to 5.56) | |
| Ever used illicit drugs | |||||||||||
| No | 344 | 80.0 | 20 | 51.3 | 1.00 | 171 | 69.0 | 52 | 25.1 | 1.00 | 0.144 |
| Yes | 86 | 20.0 | 19 | 48.7 | 3.76 (1.92 to 7.37) | 77 | 31.0 | 155 | 74.9 | 6.72 (4.41 to 10.26) | |
p Values of interactions by gender: within earlier cohort—current smoking by gender, p=0.465, excessive drinking by gender, p=0.742, ever illicit drugs by gender, p=0.795; within later cohort—current smoking by gender, p=0.145, excessive drinking by gender, p=0.841, ever illicit drugs by gender, p=0.003.
↵* Adjusted for social class and age.
↵† Defined as ≥22 units in the past week for boys, ≥15 units for girls.