Table 3

Rates of early sexual initiation according to early adolescent use and associated ORs (unadjusted for other substance use) in each cohort, by gender

1987/1990 (‘earlier’) cohort1999/2003 (‘later’) cohortp Value of interaction with cohort
No early sexual initiationEarly sexual initiationOR (95% CI)*No early sexual initiationEarly sexual initiationOR (95% CI)*
N%N%N%N%
Boys
 Started smoking at age <14
  No26183.96158.71.0028887.39264.31.000.879
  Yes5016.14341.33.64 (2.20 to 6.02)4212.75135.73.45 (2.14 to 5.58)
 Monthly drinking at age 15
  No25280.86259.61.0014844.83222.41.000.780
  Yes6019.24240.43.00 (1.84 to 4.92)18255.211177.62.74 (1.74 to 4.32)
 Ever used illicit drugs at age 15
  No28792.37673.11.0021063.86042.01.000.159
  Yes247.72826.94.11 (2.24 to 7.54)11936.28358.02.42 (1.61 to 3.65)
Girls
 Started smoking at age <14
  No34379.02571.41.0029587.36351.61.000.002
  Yes9121.01028.61.46 (0.67 to 3.18)4312.75948.46.40 (3.94 to 10.39)
 Monthly drinking at age 15
  No37085.32571.41.0013840.91512.31.000.133
  Yes6414.71028.62.32 (1.04 to 5.14)19959.110787.74.93 (2.75 to 8.84)
 Ever used illicit drugs at age 15
  No40794.02982.91.0023770.13427.91.000.218
  Yes266.0617.13.09 (1.16 to 8.21)10129.98872.16.17 (3.87 to 9.83)
  • p Values of interactions by gender: within earlier cohort—started smoking at age <14 by gender, p=0.047; monthly drinking at age 15 by gender, p=0.710; ever illicit drugs at age 15 by gender, p=0.564 and within later cohort—started smoking at age <14 by gender, p=0.134, monthly drinking at age 15 by gender, p=0.118, ever illicit drugs at age 15 by gender, p=0.005.

  • * Adjusted for social class.