A novel, nonbinary evaluation of success and failure reveals bupropion efficacy versus methamphetamine dependence: reanalysis of a multisite trial

Abstract

A multisite, double-blind, placebo-controlled trial of bupropion for methamphetamine dependence was reanalyzed using a novel, nonbinary method of evaluating success and failure. The original analysis focused on a group response endpoint (the change in percentage of participants with methamphetamine-free urines each week over the course of the trial) and no significant bupropion effect was observed in the total population of study participants. In this reanalysis, individual participants were regarded as treatment success if they achieved multiple weeks of abstinence lasting through the end of the study, and their degree of success was quantified by calculating the number of beyond-threshold weeks of success (NOBWOS). Thus, setting the threshold at 1 week of end-of-study abstinence (EOSA), treatment successes were assigned NOBWOS values ranging from 1 to 11, with 1 corresponding to 2 weeks EOSA and 11 corresponding to abstinence throughput the entire 12-week trial. Treatment failures were assigned a value of 0. Comparison of NOBWOS values revealed a significant effect of bupropion to facilitate abstinence (P= 0.0176). In the bupropion group, 20% of participants achieved 2 or more weeks EOSA, 14% achieved 6 or more weeks EOSA, and 6% were abstinent throughout the trial; this compares with 7%, 4%, and 1% in the placebo group, respectively. On the basis of the NOBWOS analysis, bupropion seems to effectively facilitate the achievement of abstinence in methamphetamine-dependent individuals.

Figure 1

Effect of bupropion (150 mg twice daily) or placebo on the percentage of study participants who were in treatment and abstinence from methamphetamine through the end of the 12‐week study. In order for a week to be regarded as methamphetamine‐free, two or more methamphetamine‐free urine samples, with no methamphetamine‐positive samples, were required. Urine samples were regarded as methamphetamine‐free if they were below 300 ng/mL. This figure represents a reanalysis of data previously reported by Elkashef et al. [9]. Study participants (79 methamphetamine‐dependent individuals in the bupropion group and 72 in the placebo group) attended cognitive behavioral therapy counseling sessions and provided urine samples up to 3 times per week.

Figure 2

Success rates for achieving 2 or more weeks of EOSA as a function of self‐reported level of baseline methamphetamine use (n = 36, 27, and 15 in the bupropion group, and 35, 18, and 19 in the placebo group for study participants reporting 1–18, 19–29, and 30 days of baseline use, respectively; *P= 0.012 compared with placebo, two‐tailed Fisher's exact test).