Spending money to make change: Association of methamphetamine abstinence and voucher spending among contingency management pilot participants in South Africa

Decision-making tendencies and voucher spending independently support abstinence within contingency management for methamphetamine use disorder.

“…In this secondary analysis, spending of CM rewards was associated with a higher chance of obtaining abstinence at the future visit, as was a baseline tendency to avoid short-term rewards for larger long-term gains on the IGT. This spending result is consistent with findings from Krishnamurti et al (2020) and Ling Murtaugh et al (2013), even after controlling for decision-making tendency. However, this finding contrasts with work showing that less frequent drug use was associated with lower expenditure of money earned through participating in a job training program (Subramaniam et al, 2017).…”

“…They found that both cumulative and recent spending of cash vouchers on prosocial goods and services promoted future abstinence among a sample of U.S. treatment-seeking men with MUD, self-identifying as gay or bisexual. This recency effect was replicated by Krishnamurti et al (2020) among a sample of South African male and female participants in a CM trial for methamphetamine use, although cumulative prior expenditure did not predict future abstinence in this sample.…”

“…Models controlled for recent and cumulative earnings, recent and cumulative expenditure, as well as baseline household income. Specific to Aim (2), adjusted models were first run, controlling only for recent and cumulative expenditure and baseline household income, and were then rerun to incorporate recent and cumulative earnings (see Krishnamurti et al, 2020). All data analyses were conducted in R (R Core Team, 2020), using the survival package, version 3.2-13 (Therneau, 2021).…”

“…Data presented in this manuscript are also available in Lake et al ( 2020) and Krishnamurti et al (2020). Manuscript data and code are available from corresponding author upon request.…”

Participant perspectives on incentives for TB preventative therapy adherence and reduced alcohol use: A qualitative study

“…Additionally, participant-reported effectiveness associated with a sufficiently-sized incentive is consistent with a considerable body of prior CM literature in which increasing incentive size is associated with a dose-response effect on CM effectiveness, regardless of the substance studied or behavior incentivized [ 21 – 23 ]. Finally, while immediacy of incentive provision is considered key to CM efficacy [ 21 , 24 ], prompt spending of the incentive has been associated with more pronounced behavior change (compared to saving) [ 25 ]. Participant report of great satisfaction with spending their incentive on key items immediately, often on the way home from their study visits, is consistent with those prior findings, and highlights the importance of careful selection of incentive type and size in future incentive-based interventions.…”