6. Sensitivity analysis.
| Outcome | Classification | Subgroup | N studies | N intervention | N control | Estimate, 95% CI | I² |
| Intracluster correlation coefficient (ICC): use of lowest ICC (studies with short‐term follow‐up only) | |||||||
| Tobacco use | Individual Targeted | Highest ICC | 2 | 280 | 241 | 1.28, 0.75 to 2.19 | 0 |
| Lowest ICC | 2 | 280 | 241 | 1.28, 0.75 to 2.19 | 0 | ||
| Individual Universal | Highest ICC | 2 | 925 | 624 | 1.03, 0.32 to 3.27 | 38 | |
| Lowest ICC | 2 | 925 | 624 | 1.03, 0.32 to 3.27 | 38 | ||
| Family Targeted | Highest ICC | 2 | 160 | 153 | 0.78, 0.40 to 1.53 | 0 | |
| Lowest ICC | 2 | 160 | 153 | 0.78, 0.40 to 1.53 | 0 | ||
| School Universal | Highest ICC | 9 | 8365 | 6989 | 0.77, 0.60 to 0.97 | 57 | |
| Lowest ICC | 9 | 8365 | 6989 | 0.76, 0.59 to 0.97 | 65 | ||
| Alcohol use | Individual Targeted | Highest ICC | 4 | 1204 | 840 | 1.02, 0.79 to 1.30 | 48 |
| Lowest ICC | 4 | 1204 | 840 | 1.02, 0.79 to 1.30 | 48 | ||
| Individual Universal | Highest ICC | 4 | 1105 | 806 | 0.80, 0.58 to 1.11 | 0 | |
| Lowest ICC | 4 | 1105 | 806 | 0.80, 0.58 to 1.11 | 0 | ||
| Family Targeted | Highest ICC | 3 | 212 | 205 | 0.83, 0.47 to 1.46 | 29 | |
| Lowest ICC | 3 | 212 | 205 | 0.83, 0.47 to 1.46 | 29 | ||
| School Targeted | Highest ICC | 1 | 615 | 603 | 1.03, 0.56 to 1.91 | ‐‐ | |
| Lowest ICC | 1 | 615 | 603 | 1.03, 0.56 to 1.91 | ‐‐ | ||
| School Universal | Highest ICC | 8 | 4382 | 4369 | 0.72, 0.56 to 0.92 | 58 | |
| Lowest ICC | 8 | 4382 | 4369 | 0.71, 0.55 to 0.91 | 60 | ||
| Binge drinking | Individual Targeted | Highest ICC | 3 | 130 | 120 | 0.97, 0.68 to 1.37 | 0 |
| Lowest ICC | 3 | 130 | 120 | 0.97, 0.68 to 1.37 | 0 | ||
| School Universal | Highest ICC | 5 | 2825 | 2669 | 0.66, 0.41 to 1.06 | 43 | |
| Lowest ICC | 5 | 2825 | 2669 | 0.66, 0.45 to 0.99 | 49 | ||
| Cannabis use | Individual Targeted | Highest ICC | 2 | 67 | 59 | 1.10, 0.71 to 1.97 | 0 |
| Lowest ICC | 1 | 67 | 59 | 1.10, 0.71 to 1.97 | 0 | ||
| Individual Universal | Highest ICC | 2 | 180 | 182 | 0.69, 0.46 to 1.04 | 0 | |
| Lowest ICC | 2 | 79 | 83 | 0.69, 0.46 to 1.04 | 0 | ||
| Family Targeted | Highest ICC | 3 | 192 | 188 | 1.02, 0.52 to 2.02 | 43 | |
| Lowest ICC | 3 | 192 | 188 | 1.02, 0.52 to 2.02 | 43 | ||
| School Universal | Highest ICC | 5 | 1924 | 2216 | 0.79, 0.62 to 1.01 | 0 | |
| Lowest ICC | 5 | 1924 | 2216 | 0.77, 0.61 to 0.97 | 0 | ||
| Illicit drug use | Individual Targeted | Highest ICC | 3 | 342 | 296 | 0.94, 0.71 to 1.25 | 0 |
| Lowest ICC | 3 | 342 | 296 | 0.94, 0.71 to 1.25 | 0 | ||
| Family Targeted | Highest ICC | 1 | 33 | 36 | 0.74, 0.42 to 1.31 | ‐‐ | |
| Lowest ICC | 1 | 33 | 36 | 0.74, 0.42 to 1.31 | ‐‐ | ||
| School Targeted | Highest ICC | 4 | 1431 | 1023 | 0.75, 0.53 to 1.06 | 60 | |
| Lowest ICC | 4 | 1431 | 1023 | 0.75, 0.53 to 1.06 | 60 | ||
| School Universal | Highest ICC | 5 | 4745 | 6313 | 0.74, 0.55 to 1.00 | 69 | |
| Lowest ICC | 5 | 4715 | 6313 | 0.74, 0.54 to 1.03 | 82 | ||
| Tobacco, alcohol, and/or illicit drug use | Family Targeted | Highest ICC | 2 | 115 | 98 | 0.81, 0.50 to 1.33 | 0 |
| Lowest ICC | 2 | 115 | 98 | 0.81, 0.50 to 1.33 | 0 | ||
| School Targeted | Highest ICC | 5 | 244 | 98 | 0.55, 0.24 to 1.25 | 69 | |
| Lowest ICC | 5 | 244 | 98 | 0.54, 0.24 to 1.21 | 71 | ||
| School Universal | Highest ICC | 2 | 2771 | 4256 | 1.13, 0.88 to 1.44 | 0 | |
| Lowest ICC | 2 | 2771 | 4256 | 1.10, 1.01 to 1.20 | 0 | ||
| Antisocial behaviour | Individual Targeted | Highest ICC | 4 | 409 | 355 | 1.21, 0.92 to 1.60 | 19 |
| Lowest ICC | 4 | 409 | 355 | 1.21, 0.92 to 1.60 | 19 | ||
| Family Targeted | Highest ICC | 6 | 437 | 335 | 0.84, 0.57 to 1.24 | 42 | |
| Lowest ICC | 6 | 437 | 335 | 0.84, 0.57 to 1.24 | 42 | ||
| Family Universal | Highest ICC | 1 | 208 | 98 | 0.87, 0.56 to 1.35 | 0 | |
| Lowest ICC | 1 | 208 | 98 | 0.87, 0.56 to 1.35 | 0 | ||
| School Targeted | Highest ICC | 3 | 815 | 716 | 0.78, 0.59 to 1.05 | 0 | |
| Lowest ICC | 3 | 815 | 716 | 0.82, 0.68 to 0.99 | 0 | ||
| School Universal | Highest ICC | 12 | 9960 | 10796 | 0.81, 0.66 to 0.98 | 66 | |
| Lowest ICC | 12 | 9960 | 10796 | 0.82, 0.69 to 0.97 | 67 | ||
| Sexual risk behaviour | Individual Targeted | Highest ICC | 2 | 266 | 228 | 0.73, 0.49 to 1.08 | 45 |
| Lowest ICC | 2 | 266 | 228 | 0.73, 0.49 to 1.08 | 45 | ||
| Individual Universal | Highest ICC | 1 | 79 | 83 | 0.42, 0.14 to 1.25 | ‐‐ | |
| Lowest ICC | 1 | 79 | 83 | 0.42, 0.14 to 1.25 | ‐‐ | ||
| Family Targeted | Highest ICC | 3 | 188 | 183 | 0.89, 0.55 to 1.44 | 0 | |
| Lowest ICC | 3 | 188 | 183 | 0.89, 0.55 to 1.44 | 0 | ||
| School Universal | Highest ICC | 6 | 5757 | 6876 | 0.83, 0.61 to 1.12 | 77 | |
| Lowest ICC | 6 | 5757 | 6876 | 0.83, 0.61 to 1.12 | 77 | ||
| Physical activity | Individual Universal | Highest ICC | 2 | 748 | 782 | 1.11, 0.74 to 1.67 | 0 |
| Lowest ICC | 2 | 748 | 782 | 1.11, 0.74 to 1.67 | 0 | ||
| Family Targeted | Highest ICC | 1 | 31 | 30 | 0.72, 0.29 to 1.79 | ‐‐ | |
| Lowest ICC | 1 | 31 | 30 | 0.72, 0.29 to 1.79 | ‐‐ | ||
| School Universal | Highest ICC | 4 | 3547 | 2894 | 1.32, 1.16 to 1.50 | 0 | |
| Lowest ICC | 4 | 3547 | 2894 | 1.33, 1.18 to 1.50 | 0 | ||
| Nutrition (BMI) | Individual Universal | Highest ICC | 1 | 421 | 158 | 0.80, 0.48 to 1.31 | ‐‐ |
| Lowest ICC | 1 | 421 | 158 | 0.80, 0.48 to 1.31 | ‐‐ | ||
| School Universal | Highest ICC | 3 | 2901 | 2116 | 0.84, 0.60 to 1.19 | 61 | |
| Lowest ICC | 3 | 2901 | 2116 | 0.88, 0.62 to 1.23 | 69 | ||
| Nutrition (unhealthy diet) | Individual Universal | Highest ICC | 2 | 925 | 624 | 0.76, 0.42 to 1.34 | 51 |
| Lowest ICC | 2 | 925 | 624 | 0.76, 0.42 to 1.34 | 51 | ||
| School Universal | Highest ICC | 3 | 3608 | 2833 | 0.82, 0.64 to 1.06 | 49 | |
| Lowest ICC | 3 | 3608 | 2833 | 0.85, 0.66 to 1.09 | 63 | ||
| Educational attainment (academic performance) | Individual Targeted | Highest ICC | 1 | 67 | 59 | 1.34, 0.71 to 2.52 | ‐‐ |
| Lowest ICC | 1 | 67 | 59 | 1.34, 0.71 to 2.52 | ‐‐ | ||
| School Targeted | Highest ICC | 3 | 619 | 628 | 0.91, 0.30 to 2.73 | 84 | |
| Lowest ICC | 3 | 619 | 628 | 0.91, 0.39 to 2.14 | 85 | ||
| School Universal | Highest ICC | 3 | 602 | 393 | 0.94, 0.62 to 1.44 | 0 | |
| Lowest ICC | 3 | 602 | 393 | 0.95, 0.74 to 1.22 | 0 | ||
| Dichotomous vs continuous outcomes (studies with positive findings; 12‐month follow‐up only) | |||||||
| Tobacco use | School Universal | All | 9 | 8365 | 6989 | 0.77, 0.60 to 0.97, P = 0.03 | 57 |
| Dichotomous | 7 | 7581 | 6275 | 0.72, 0.52 to 0.99, P = 0.05 | 60 | ||
| Continuous | 2 | 784 | 714 | SMD ‐0.01,‐0.40 to 0.37, P = 0.95 | 84 | ||
| Alcohol use | School Universal | All | 8 | 4382 | 4369 | 0.72, 0.56 to 0.92, P = 0.009 | 58 |
| Dichotomous | 6 | 3598 | 3663 | 0.68, 0.51 to 0.90, P = 0.008 | 48 | ||
| Continuous | 2 | 784 | 706 | SMD ‐0.12, ‐0.46 to 0.22; P = 0.49 | 79 | ||
| Illicit drug use | School Universal | All | 5 | 4745 | 6313 | 0.74, 0.55 to 1.00, P = 0.05 | 69 |
| Dichotomous | 4 | 2932 | 2808 | 0.67, 0.49 to 0.93 | 62 | ||
| Continuous | 1 | 1813 | 3505 | SMD 0.06, 0.00 to 0.12, P = 0.04 | ‐‐ | ||
| Cannabis use | School Universal | All | 5 | 1924 | 2216 | 0.79, 0.62 to 1.01, P = 0.06 | 0 |
| Dichotomous | 4 | 1832 | 2130 | 0.82, 0.64 to 1.06, P = 0.13 | 0 | ||
| Continuous | 1 | 92 | 86 | SMD ‐0.29, ‐0.58 to 0.01, P = 0.06 | ‐‐ | ||
| Antisocial behaviour | School Universal | All | 13 | 8445 | 9277 | 0.79, 0.64 to 0.97, P = 0.02 | 68 |
| Dichotomous | 4 | 4042 | 4339 | 0.55, 0.30 to 1.01, P = 0.06 | 87 | ||
| Continuous | 9 | 5708 | 6255 | SMD ‐0.06, ‐0.11 to ‐0.0, P = 0.03 |
31 | ||
| Sexual risk behaviour | School Universal | All | 6 | 5757 | 6876 | 0.83, 0.61 to 1.12 | 77 |
| Dichotomous | 4 | 3020 | 2635 | 0.71, 0.39 to 1.30, P = 0.27 | 84 | ||
| Continuous | 2 | 2737 | 4241 | SMD ‐0.03, ‐0.08 to 0.02, P = 0.2 | 0 | ||
| Studies conducted in all countries vs high‐income countries only (studies with up to 12‐month follow‐up; meta‐analyses incorporating relevant data only) | |||||||
| Tobacco use | Individual Universal | All | 2 | 925 | 624 | 1.03, 0.32 to 3.27 | 38 |
| High‐income countries only | 1 | 504 | 466 | 0.74, 0.43 to 1.28 | ‐‐ | ||
| Alcohol use | Individual Universal | All | 4 | 1105 | 806 | 0.80, 0.58 to 1.11 | 0 |
| High‐income countries only | 3 | 684 | 648 | 0.74, 0.54 to 1.06 | 0 | ||
| Antisocial behaviour | School Universal | All | 13 | 9960 | 10796 | 0.81, 0.66 to 0.98 | 66 |
| High‐income countries only | 12 | 8445 | 9277 | 0.79, 0.64 to 0.97 | 68 | ||
| Sexual risk behaviour | School Universal | All | 6 | 5757 | 6876 | 0.83, 0.61 to 1.12 | 77 |
| High‐income countries only | 5 | 5654 | 6779 | 0.81, 0.59 to 1.11 | 80 | ||
| Physical activity | Individual Universal | All | 2 | 748 | 782 | 1.11, 0.74 to 1.67 | 0 |
| High‐income countries only | 1 | 504 | 466 | 1.40, 0.67 to 2.94 | ‐‐ | ||
| School Universal | All | 4 | 3547 | 2894 | 1.32, 1.16 to 1.50 | 0 | |
| High‐income countries only | 3 | 2533 | 1834 | 1.44, 1.20 to 1.74 | 0 | ||
| Unhealthy diet | Individual Universal | All | 2 | 925 | 624 | 0.76, 0.42 to 1.34 | 51 |
| High‐income countries only | 1 | 504 | 466 | 0.50, 0.23 to 1.08 | ‐‐ | ||
| School Universal | All | 3 | 3608 | 2833 | 0.82, 0.64 to 1.06 | 49 | |
| High‐income countries only | 2 | 2594 | 1773 | 0.95, 0.76 to 1.19 | 0 | ||
CI: confidence interval.
ICC: intracluster correlation coefficient.