Aims

Methamphetamine Use Disorder is prevalent in South Africa. This analysis uses data from a contingency management (CM) pilot study in South Africa to replicate and expand on a U.S.-based study showing that CM voucher spending was associated with drug abstinence behavior.

Design

Participants with methamphetamine-use disorder were enrolled in an 8-week CM trial requiring thrice weekly visits and received cash vouchers in exchange for stimulant-negative urines at each visit.

Participants

Participants were 33 treatment-seeking individuals with methamphetamine use disorder including 22 men (66.7%) and 11 women (33.3%) with a mean age of 34 years (S.D. = 7.7). Participants reported using methamphetamine for a mean of 11.7 years (S.D. = 4.9).

Setting

All study procedures took place in South Africa between August 2016 and May 2018.

Measurements

A time-lagged counting process Cox Proportional Hazards model for recurrent event survival analysis examined the relationship between frequency of and participant-categorized type of CM expenditures (hedonic, utilitarian, consumable or durable) and drug abstinence.

Findings

After controlling for severity of baseline methamphetamine use and accumulated CM earnings (proxied by cumulative negative urines), those spending CM earnings at a previous visit ("spenders") were more likely to produce stimulant-negative urine samples subsequently, compared to those who did not ("savers") [OR = 1.23, CI = 1.08-1.53, p = .002]. There were significantly more cumulative stimulant-negative results among spenders vs. savers, p < .001, although cumulative spending did not significantly predict abstinence once spending in the prior time period was controlled for, suggesting a recency effect tied to the underlying spending mechanism. When extending the original analyses to look at the effect of spending on current abstinence, controlling only for recent abstinence (rather than cumulative abstinence), spending was no longer a significant predictor. Spending type did not affect methamphetamine abstinence. Qualitative results suggest spending CM vouchers may support social reintegration over the course of the trial.

Conclusions

Abstinence outcomes are a function of CM spending in both the U.S. and South Africa. Findings of a significant relationship between contingency management spending and subsequent stimulant-negative urine samples across geographic locations provide guidance toward future work in optimizing CM efficacy.

Objectives

Contingency management is a promising intervention for Methamphetamine Use Disorder (MUD).Impaired executive function may decrease adherence to such treatment, but there are few data on whether impairment in executive function predicts treatment outcomes. We therefore evaluated whether baseline performance on tests of executive function predicted treatment response in a trial of contingency management for MUD.

Methods

Thirty participants with MUD and 23 healthy controls performed the Connors Continuous Performance Task (CPT) and the Trail Making Task. MUD participants then entered an 8-week contingency management trial. Participants were categorized as responders (n=17; no methamphetamine-positive urine tests) or non-responders (n=13; >1 positive test). The Kruskal-Wallis test was used to compare scores in participants with MUD and healthy controls, and in responders versus non-responders.

Results

Participants withMUD performed worse than controls on the CPT (d-prime) (p=0.012); non-responders performed worse than responders (p = 0.034). Performance of MUD participants did not differ significantly from controls on the Trail Making Task B (time to completion), but variation was high with non-responders performing worse than responders (p=0.013).

Conclusion

These findings suggest that tests of executive function at baseline may be useful in predicting treatment response in MUD. Future work in larger samples may ultimately allow a more personalized treatment approach to methamphetamine use disorder.

Decision-making tendencies and spending within cash voucher-based interventions have individually been shown to be related to future abstinence among participants with methamphetamine use disorder (MUD), but less is known of their independent contributions. This study of participants in a contingency management (CM) trial investigated whether decision-making and spending were each associated with future abstinence. Thirty-two outpatients with MUD, predominately male (68%) and mixed ancestry (94%) with a median age of 34 years, participated in an 8-week cash voucher-based CM pilot trial. Prior to commencing the trial, participants completed a computerized Iowa Gambling Task (IGT) to measure decision-making preferences for more frequent rewards and longer term gains of greater magnitude. Spending and abstinence of participants were tracked over the duration of the trial. In a secondary analysis, time-lagged counting process Cox Proportional Hazard models were conducted. Baseline decision-making, characterized by a preference for frequent rewards, was associated with a greater likelihood of future spending, Hazard Ratio; HR = 1.13 [1.06: 1.21]. Avoidance of short-term rewards to realize longer term, higher magnitude rewards, and spending at the prior visit were each associated with abstinence on the trial, HR = 1.12 [1.03: 1.22] and HR = 1.32 [1.08: 1.61], respectively. Controlling for decision-making, spending, and cumulative abstinence, prior abstinence remained the largest predictor of future abstinence, HR = 3.85 [2.88: 5.16]. Decision-making tendencies and spending are correlated yet independently associated with abstinence reinforcement in CM. Findings highlight the opportunity for behavioral treatment programs to tailor program structures to individual-specific characteristics. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Introduction and aims

As South Africa, especially the Western Cape Province, faces an epidemic of methamphetamine use disorder, therapeutic approaches suited to the South African context are needed. This secondary analysis assessed retention and methamphetamine abstinence outcomes in response to an 8-week pilot contingency management (CM) intervention trial of neural correlates of methamphetamine abstinence, exploring sociodemographic and clinical differences between responders and non-responders.

Design and methods

Research participants provided thrice-weekly monitored urine samples, which were analysed by qualitative radioimmunoassay. The primary outcome for this analysis was therapeutic response, defined as abstinence from methamphetamine (≥23 of 24 possible methamphetamine-negative urine samples).

Results

Data from 30 adults living in Cape Town, South Africa (34 ± 6.1 years of age, mean age ± SD, 21 men) were included. Sixty-three percent (12 men) were responders. In bivariate comparisons, baseline measurements showed fewer responders reported monthly household income ≥25 000+ South African Rand (ZAR; ~USD $1880; vs. ZAR < 25 000) than non-responders (15.8% vs. 63.6%; P = 0.007). Furthermore, responders had higher median years of education (12 vs. 10; Kruskal-Wallis χ² = 4.25, DF = 1, P = 0.039) and lower median body mass index than non-responders (19 vs. 24; Kruskal-Wallis χ² = 6.84, P = 0.008).

Discussion and conclusions

Therapeutic response in this study were comparable to those obtained with CM for methamphetamine use disorder in North America and Europe. Our findings suggest that CM may be a useful component of treatment strategies to boost retention and continuous abstinence from methamphetamine in Cape Town, South Africa. Larger efficacy studies are needed in this setting.

Introduction and aims

As South Africa, especially the Western Cape Province, faces an epidemic of methamphetamine use disorder, therapeutic approaches suited to the South African context are needed. This secondary analysis assessed retention and methamphetamine abstinence outcomes in response to an 8-week pilot contingency management (CM) intervention trial of neural correlates of methamphetamine abstinence, exploring sociodemographic and clinical differences between responders and non-responders.

Design and methods

Research participants provided thrice-weekly monitored urine samples, which were analysed by qualitative radioimmunoassay. The primary outcome for this analysis was therapeutic response, defined as abstinence from methamphetamine (≥23 of 24 possible methamphetamine-negative urine samples).

Results

Data from 30 adults living in Cape Town, South Africa (34 ± 6.1 years of age, mean age ± SD, 21 men) were included. Sixty-three percent (12 men) were responders. In bivariate comparisons, baseline measurements showed fewer responders reported monthly household income ≥25 000+ South African Rand (ZAR; ~USD $1880; vs. ZAR < 25 000) than non-responders (15.8% vs. 63.6%; P = 0.007). Furthermore, responders had higher median years of education (12 vs. 10; Kruskal-Wallis χ² = 4.25, DF = 1, P = 0.039) and lower median body mass index than non-responders (19 vs. 24; Kruskal-Wallis χ² = 6.84, P = 0.008).

Discussion and conclusions

Therapeutic response in this study were comparable to those obtained with CM for methamphetamine use disorder in North America and Europe. Our findings suggest that CM may be a useful component of treatment strategies to boost retention and continuous abstinence from methamphetamine in Cape Town, South Africa. Larger efficacy studies are needed in this setting.

Background

Individuals with substance use disorders exhibit maladaptive decision-making on the Iowa Gambling Task (IGT), which involves selecting from card decks differing in the magnitudes of rewards, and the frequency and magnitude of losses. We investigated whether baseline IGT performance could predict responses to contingency management (CM) by treatment-seeking individuals with methamphetamine use disorder (MA Use Disorder) in Cape Town, South Africa.

Methods

Twenty-nine individuals with MA Use Disorder underwent an 8-week, escalating reinforcement, voucher-based CM treatment in a study on the suitability of CM therapy for the South African context. Along with 20 healthy control participants, they performed a computerized version of the IGT before starting CM treatment. Seventeen participants maintained abstinence from methamphetamine throughout the trial (full responders), and 12 had an incomplete response (partial responders). Performance on the IGT was scored for magnitude effect (selection of large immediate rewards with high long-term loss) and for frequency effect (preference for frequent rewards and avoidance of frequent losses). Group differences were investigated using linear mixed-effect modeling.

Results

Partial responders made more selections from decks providing large, immediate rewards and long-term losses than healthy controls [p = 0.038, g = -0.77 (-1.09: -0.44)]. Full responders showed a greater, nonsignificant preference for frequent rewards and aversion to frequent losses than partial responders [p = 0.054, g = -0.63 (-0.95: -0.29)].

Conclusions

A predilection for choices based on the size and immediacy of reward may reflect a cognitive strategy that works against CM. Pretesting with a decision-making task, such as the IGT, may help in matching cognitive therapies to clients with MA Use Disorder.

Background

Individuals with substance use disorders exhibit maladaptive decision-making on the Iowa Gambling Task (IGT), which involves selecting from card decks differing in the magnitudes of rewards, and the frequency and magnitude of losses. We investigated whether baseline IGT performance could predict responses to contingency management (CM) by treatment-seeking individuals with methamphetamine use disorder (MA Use Disorder) in Cape Town, South Africa.

Methods

Twenty-nine individuals with MA Use Disorder underwent an 8-week, escalating reinforcement, voucher-based CM treatment in a study on the suitability of CM therapy for the South African context. Along with 20 healthy control participants, they performed a computerized version of the IGT before starting CM treatment. Seventeen participants maintained abstinence from methamphetamine throughout the trial (full responders), and 12 had an incomplete response (partial responders). Performance on the IGT was scored for magnitude effect (selection of large immediate rewards with high long-term loss) and for frequency effect (preference for frequent rewards and avoidance of frequent losses). Group differences were investigated using linear mixed-effect modeling.

Results

Partial responders made more selections from decks providing large, immediate rewards and long-term losses than healthy controls [p = 0.038, g = -0.77 (-1.09: -0.44)]. Full responders showed a greater, nonsignificant preference for frequent rewards and aversion to frequent losses than partial responders [p = 0.054, g = -0.63 (-0.95: -0.29)].

Conclusions

A predilection for choices based on the size and immediacy of reward may reflect a cognitive strategy that works against CM. Pretesting with a decision-making task, such as the IGT, may help in matching cognitive therapies to clients with MA Use Disorder.