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Table 6 Mean frequency of cannabis, meth/amphetamine and ecstasy use (95% confidence interval and sample size), for the intervention and control groups, over time

From: A universal harm-minimisation approach to preventing psychostimulant and cannabis use in adolescents: a cluster randomised controlled trial

  

Baseline

Post

Five month follow-up

10 month follow-up

Frequency of cannabis use in last three months a

Control

0.24

0.25

0.27

0.29

(0.18-0.30)

(0.17-0.33)

(0.19-0.35)

(0.19-0.39)

(n = 823)

(n = 579)

(n = 447)

(n = 403)

Intervention

0.12

0.15

0.22

0.16

(0.08-0.16)

(0.09-0.21)

(0.14-0.30)

(0.10-0.22)

(n = 898)

(n = 626)

(n = 614)

(n = 568)

Frequency of meth/amphetamine use in last 12 months b

Control

0.12

0.13

0.09

0.10

(0.04-0.12)

(0.02-0.10)

(0.07-0.15)

(0.07-0.15)

(n = 824)

(n = 578)

(n = 449)

(n = 403)

Intervention

0.08

0.06

0.11

0.09

(0.04-0.12)

(0.02-0.10)

(0.07-0.15)

(0.05-0.13)

(n = 904)

(n = 628)

(n = 614)

(n = 569)

Frequency of ecstasy use in last 12 months b

Control

0.15

0.18

0.16

0.12

(0.11-0.19)

(0.12-0.24)

(0.10-0.22)

(0.10-0.22)

(n = 824)

(n = 578)

(n = 447)

(n = 403)

Intervention

0.10

0.10

0.12

0.11

(0.06-0.14)

(0.06-0.14)

(0.08-0.16)

(0.07-0.15)

(n = 904)

(n = 628)

(n = 614)

(n = 569)

  1. aFrequency was coded as: 0 = Have not used in the last 3 months, 1 = About once a month, 2 = Less than once a week, 3 = About once a week, 4 = More than once a week (but less than daily), 5 = Once a day, 6 = More than once per day.
  2. bFrequency was coded as: 0 = Have not used in the last 12 months, 1 = once or twice a year, 2 = Every few months, 3 = About once a month, 4 = Once a week or more, 5 = every day.