Abstract
BACKGROUND: Contingency management (CM) is an effective intervention that provides financial incentives as positive reinforcement for reducing opioid or stimulant use. However, it has not been tested in populations of women who inject drugs (WWID) engaging in polysubstance use. METHODS: We aimed to compare the feasibility of two CM protocols designed to encourage illicit stimulant and opioid abstinence among WWID participating in an ongoing HIV prevention trial. Participants completed a 3-month CM period during which they submitted thrice weekly urine toxicology screenings (UTOX). In the 'abstinence from stimulants and opioids' protocol, participants received a $5 USD incentive when metabolites of stimulants and opioids were not detected in urine. In the 'partial-abstinence protocol', they received a $5 USD incentive when metabolites of stimulants or opioids were not detected, thus doubling the potential incentive obtained each visit. Women also received scaling bonuses after three consecutive negative UTOX ($5-$15 USD). We used descriptive statistics to summarize the total number of (1) UTOXs completed and (2) bonuses distributed. Rates of engagement per person per month were calculated (i.e., total number of completed UTOX/3 months*24 participants). Rates of engagement were compared by CM protocol period. RESULTS: Participants were primarily White women (67%) with an average age of 47 years. Self-reported polysubstance use was common (96%) with women reporting injecting an average of 5 times daily (Interquartile Range: 2-7). Participants (N = 24) collectively submitted 177 UTOX during their 3-month CM periods. Rates of non-reactive UTOX results were slightly higher in the partial-abstinence protocol compared to the abstinence from stimulants and opioids protocol (2.9 per month versus 1.0 per month). More bonuses were earned in the partial-abstinence protocol (0.50 bonuses per participant per month) compared to the abstinence from stimulants and opioids protocol (none). There were no study related adverse events in either protocol group during the CM period. CONCLUSIONS: Findings demonstrate the feasibility of a CM protocol that provided financial incentives for partial abstinence, periods with documented stimulant or opioid abstinence, as well as abstinence to both, without the occurrence of iatrogenic effects. Future research focusing on CM protocols with more flexible incentive structures remains critical. TRIAL REGISTRATION: NCT05192434.