Objectives: The accelerated development of additive pharmacotherapy treatment (ADAPT-2) for methamphetamine use disorder (MUD) trial demonstrated the efficacy of extended-release injectable naltrexone (NTX) and oral bupropion (BUP). In this secondary analysis, we determined whether craving and impulsivity levels could predict subsequent use of methamphetamine.
Methods: Participants (N = 357) of the ADAPT-2 trial with at least one transition point [transition from positive-to-negative urine drug screen (UDS) or vice versa] during stage 1 (baseline through week-6) were included in this secondary analysis. Craving was assessed using the Visual Analog Scale (VAS). Impulsivity was assessed using the 2-item impulsivity factor of the Concise Health Risk Tracking (CHRT) Scale.
Results: A significant treatment by craving by time interaction was noted ( P = 0.018), where higher craving levels were consistently associated with a lower likelihood positive-to-negative UDS transition at the next visit in both NTX-BUP and placebo groups. However, no such effect was present by week 6 of treatment in the placebo group. CHRT Impulsivity also had a significant effect on the probability of a positive-to-negative UDS transition ( P = 0.019) in addition to the 3-way interaction of VAS, week, and treatment group. Individuals with lower craving levels but higher impulsivity exhibited a lower probability of transitioning to negative UDS at the next visit. Higher craving, but not impulsivity, was associated with a higher likelihood of negative-to-positive UDS transition at the next visit in both treatment groups.
Conclusions: Further investigations are necessary to optimize NTX-BUP treatment, focusing on the impact of craving and impulsivity on outcomes.
Trial registration: ClinicalTrials.gov NCT03078075.
Keywords: ADAPT-2; craving; impulsivity; methamphetamine use disorder; treatment outcome.
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