Table 2.
Attendance and abstinence outcomes
| Variable | Standard care (n = 122) | CM (n = 117) | Significance test Value (df), p-value | Effect size Cohen’s d | |||
|---|---|---|---|---|---|---|---|
| Days attended treatment | 14.7 ± 9.6 | 17.0 ± 8.9 | t (237) = 1.93, p =.05 | 0.25 | |||
| Continuous weeks of attendance | 4.1 + 3.7 | 5.7 + 4.3 | t (237) = 3.17, p =.002 | 0.40 | |||
| Proportion of expected days attended treatment | 77.2 ± 26.7 | 83.8 ± 23.1 | t (237) = 2.04, p =.05 | 0.26 | |||
| Longest duration of abstinence from all reinforced substances (in weeks) | 4.1 ± 3.6 | 5.3 ± 4.2 | t (237) = 2.47, p =.02 | 0.31 | |||
| Cocaine | 4.3 ± 3.7 | 5.8 ± 4.3 | t (237) = 2.72, p =.01 | 0.37 | |||
| Methamphetamine | 5.1 ± 3.8 | 6.4 ± 3.9 | t (237) = 2.57, p =.02 | 0.34 | |||
| Opioids | 4.8 ± 3.8 | 6.2 ± 4.0 | t (237) = 2.72, p =.01 | 0.39 | |||
| Alcohol | 4.8 ± 3.7 | 6.4 ± 4.0 | t (237) = 3.13, p =.01 | 0.42 | |||
| Marijuanaa | 4.9 ± 3.8 | 6.1 ± 4.1 | t (237) = 2.27, p =.03 | 0.30 | |||
| Proportion of samples negative from all reinforced substances | 79.6 ± 30.0 | 83.6 ± 27.2 | t (237) = 1.06, p = .29 | 0.14 | |||
| Cocaine | 84.7 ± 27.8 | 87.0 ± 25.4 | t (237) = 0.68, p =.50 | 0.09 | |||
| Methamphetamine | 97.8 ± 8.1 | 98.7 ± 7.2 | t (237) = 0.92, p =.36 | 0.12 | |||
| Opioids | 91.8 ± 21.8 | 95.4 ± 14.4 | t (237) = 1.51, p =.13 | 0.19 | |||
| Alcohol | 96.1 ± 10.4 | 99.3 ± 3.5 | t (237) = 1.06, p =.29 | 0.41 | |||
| Marijuanaa | 94.3 ± 17.7 | 92.4 ± 23.5 | t (237) = −0.71, p =.48 | −0.09 | |||
Values represent means and standard deviations.
a
Marijuana abstinence was not reinforced.
CM=contingency management