Twenty-three RCTs (n=2,112) were included in the review. Completion of treatment across all drug treatment arms ranged from 11% to 90%. Methadone was compared to clonidine (five trials) lofexidine (two trials) and buprenorphine (three trials). Buprenorphine was compared to clonidine in eight trials and lofexidine in one trial. Four trials evaluated comparisons between clonidine and lofexidine. The methodological quality of the studies was not reported.
There were statistically significant higher rates of completion of detoxification treatment observed with buprenorphine compared to clonidine in mixed treatment meta-analysis (OR 3.95, 95% CrI 2.01 to 7.46) and direct comparison analysis (OR 2.22, 95% CrI 1.10 to 4.26). Methadone was observed to be associated with significantly higher rates of treatment completion than clonidine in the mixed treatment comparison (OR 2.42, 95% CrI 1.07 to 5.37).
Buprenorphine was associated with non-statistically significant trends towards benefits for treatment completion compared to methadone and lofexidine. A non-significant benefit was observed for methadone compared to lofexidine. There were no statistically significant differences between lofexidine and clonidine.
Buprenorphine was found to have the highest probability of being the most effective treatment (0.85), followed by methadone (0.12), lofexidine (0.03) and clonidine (0.0001).