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Table 1 Effect sizes and number needed to treat for changes relative to control group in any drinking, binge drinking and alcohol-related harms. Effect sizes are based on Intervention x Time coefficients from latent growth models used to analyze intervention outcomes [16, 58], converting the estimated odds ratios to standardised mean differences d [59]

From: Pathways to prevention: protocol for the CAP (Climate and Preventure) study to evaluate the long-term effectiveness of school-based universal, selective and combined alcohol misuse prevention into early adulthood

Participants Outcome Intervention group b OR d NNT
All participants
(at 24 months post baseline)
Any drinking Climate* −0.38 0.47 −0.42 7
Preventure* −0.36 0.49 −0.40 7
CAP* −0.19 0.68 −0.21 12
Binge drinking Climate* −0.51 0.36 −0.56 9
Preventure* −0.41 0.44 −0.45 10
CAP* −0.36 0.49 −0.40 11
Alcohol-related harms Climate −0.23 0.63 −0.25 10
Preventure* −0.38 0.47 −0.42 6
CAP −0.19 0.68 −0.21 12
High-risk participants
(at 36 months post baseline)
Any drinking Preventure* −0.225 0.51 −0.37 7
Binge drinking Preventure* −0.305 0.40 −0.50 6
Alcohol-related harms Preventure* −0.255 0.47 −0.42 6
  1. *: significant at p < 0.05
  2. b: Intervention x Time coefficient
  3. OR: Estimated odds ratio
  4. d: Estimated effect size (standardised mean difference)
  5. NNT: Number needed to treat to benefit (based on OR and the event rate in the control group)
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