Summary of findings for the main comparison. Brief intervention compared to information provision for substance‐using adolescents.
| Brief intervention compared to information provision for substance‐using adolescents | ||||||
| Patient or population: Substance‐using adolescents Settings: High schools or further education training colleges Intervention: Brief intervention Comparison: Information provision | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Estimate effect (95% CI) | No of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Information provision | Brief intervention | |||||
| Alcohol frequency Self report questionnaires Medium‐term follow‐up: 4 to 6 months | See comment | The standardised mean alcohol frequency in the intervention groups was 0.01 standard deviations lower (0.20 lower to 0.18 higher) | SMD ‐0.01 (‐0.20 to 0.18) | 434 (2 studies) | ⊕⊕⊕⊝ moderate1 | Number of days of alcohol use |
|
Alcohol quantity
Self report questionnaires Medium‐term follow‐up: 4 to 6 months |
See comment | The standardised mean alcohol quantity in the intervention groups was 0.14 standard deviations lower (0.33 lower to 0.05 higher) | SMD ‐0.14 (‐0.33 to 0.05) | 434 (2 studies) | ⊕⊕⊕⊝ moderate1 | Number of standard alcohol units |
| Cannabis dependence Self report questionnaires Short‐term follow‐up: 1 to 3 months | See comment | The standardised mean cannabis dependence score in the intervention groups was 0.09 standard deviations lower (0.27 lower to 0.09 higher) |
SMD ‐0.09 (‐0.27 to 0.09) | 470 (2 studies) | ⊕⊕⊕⊝ moderate1 | Mean dependence score |
| Cannabis frequency Self report questionnaires Short‐term follow‐up: 1 to 3 months | See comment | The mean cannabis frequency in the intervention groups was 0.07 standard deviations lower (0.25 lower to 0.11 higher) | SMD ‐0.07 (‐0.25 to 0.11) | 470 (2 studies) | ⊕⊕⊕⊝ moderate1 | Number of days cannabis use |
|
Secondary outcomes related to substance use
Self report questionnaires Short‐term follow‐up: 1 to 3 months |
See comment | The mean behavioural outcomes related to substance use in the intervention groups was ‐0.01 standard deviations lower (0.19 lower to 0.17 higher) | SMD ‐0.01 (‐0.19 to 0.17) | 470 (2 studies) | ⊕⊕⊕⊝ moderate1 | Interactional Problems Score |
| *The basis for the assumed risk (e.g. the mean control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% CI) is based on the assumed risk in the comparison group and the estimate effect of the intervention (and its 95% CI). The estimate effects for certain outcomes were not estimable due to only one study assessing the specific outcome, or extremely high levels of heterogeneity making effects across studies difficult to compare. CI: confidence interval; SMD: standardised mean difference | ||||||
| GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate. | ||||||
1Risk of bias (‐1): It was not possible to blind the participants in all of the included studies. There was also uncertainty in two of the studies about allocation concealment and blinding of outcome assessor (Walker 2011; Werch 2005).