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Table 2 Overall change in 30-day substance use (prevalence) before and six months after treatment (N = 497)

From: Therapeutic community drug treatment success in Peru: a follow-up outcome study

Type of Substance use

Before Treatment

6 months after Treatment

Difference3

Effect Size4

 

Self reported1

Self or Family reported2

Self reported1

Self or Family reported2

Self reported1

Self or Family reported2

Self reported1

Self or Family reported2

Illegal Drug use

90%

91%

34%

43%

56%***

49%***

1.12 (Large)

.98 (Large)

PCB (Coca Paste) use

62%

67%

22%

33%

40%***

35%***

.82 (Large)

.72 (Medium)

Cocaine use

30%

39%

8%

20%

22%***

19%***

.52 (Medium)

.48 (Medium)

Cannabis use

37%

45%

13%

24%

24%***

21%***

.53 (Medium)

.49 (Medium)

Alcohol use to intoxication

68%

72%

33%

42%

35%***

31%***

.67 (Medium)

.62 (Medium)

  1. Note: *p ≤ .05, **p ≤ .01, ***p ≤ .001; 1 Includes Self reported relapse (n = 497); 2 Self or Family indicated relapse (n = 573); 3Standard deviations may be calculated from percentages using the binomial approximation to the variance, where SD = (p(1 – p))2; 4Effect Size: Proportions converted to Cohen d statistic with a small effect size equals .20, a medium effect size equals .50, and a large effect size equals .80[73]