Participants in randomized controlled trials of pharmacological treatments for methamphetamine (MA) use disorder who are able to achieve a brief period of early abstinence are retained longer in the trials and are less likely to drop out overall, a recent study found. Participants’ ability to achieve a brief period of initial abstinence was measured as the number of MA-negative urine screens completed in the first 2 weeks of the trials. A total of 440 participants were included; trials were conducted between 2004 and 2014. Researchers found:

• Study participants achieved an average of 3 (of 6 possible) negative urine screens during the first 2 weeks of the trials, 51% dropped out, and the average number of days retained was 60 (of 90 maximum).
• Each additional negative urine screen achieved during the first 2 weeks of the study reduced multiplicatively the odds of dropout by 41%.
• Abstinence was also a significant predictor of retention time; the hazard ratio for non-completion was 0.75 per additional negative urine screen.