Spend today, clean tomorrow: predicting methamphetamine abstinence in a randomized controlled trial

Area of Science:

• Behavioral Economics
• Addiction Science
• Public Health

Background:

• Contingency management (CM) is an evidence-based intervention for substance use disorders.
• Understanding the economic mechanisms underlying CM effectiveness is crucial for optimizing treatment.

Purpose of the Study:

• To test behavioral economics mechanisms (substitutability and delay discounting) explaining outcomes in CM for methamphetamine dependence.
• To examine the impact of CM payment frequency and purchase types on treatment outcomes.

Main Methods:

• Secondary analysis of a randomized controlled trial involving 82 methamphetamine-dependent gay/bisexual men.
• Utilized a time-lagged Cox Proportional Hazards model to analyze CM purchase data and urine sample results over a 16-week period.

Main Results:

• Participants who redeemed CM earnings at any visit (
• spenders
• ) were significantly more likely to provide stimulant-negative urine samples at the next visit compared to
• savers
• (p < .001).
• This effect persisted after controlling for baseline methamphetamine use severity and accumulated CM wealth.

Conclusions:

• Findings support the economic principle of substitutability in CM, where redeemed goods replace the perceived value of methamphetamine.
• Treatment outcomes are better explained by the frequency of CM purchases rather than the total amount earned.
• Incentive-based programs should encourage frequent reward redemption to enhance methamphetamine abstinence.