Prize-based Incentives Contingency Management for Substance Abusers is a version of contingency management (CM) that provides adult substance abusers in community-based treatment with an opportunity to win prizes if they remain drug free. The intervention is based on the psychological theory of operant conditioning, which relies on the use of consequences to modify the occurrence and form of specific behavior. In this instance, the intervention provides reinforcement of positive behaviors that will lead to behavioral change (mainly, abstinence from drug use). Participation lasts anywhere from 2 to 4 weeks for the intensive outpatient therapy to 12 months or longer with aftercare services.
CM interventions attempt to increase positive behavior in substance abusers by offering vouchers that are redeemable for retail goods and services but are contingent on behavior change. Prize-based CM reinforces positive abstinent behavior in substance-abusing clients in treatment by providing them an opportunity to win various prizes when they provide negative urine and breath samples or complete treatment-related activities.
For example, one abstinence incentive procedure used with cocaine and methamphetamine users in community clinics invited clients who provided negative tests to draw plastic chips from a bowl, which could result in winning a prize valued from $1 to $100. Chips worth $1 allowed clients to select from a variety of popular items such as bus tokens, snacks, and fast-food gift certificates. The more valuable the dollar amount on the chip, the more valuable the items that a client could select from. A chip worth $20 allowed clients to choose from items such as compact disc players, telephones, and retail store gift certificates. Chips worth $80 to $100 allowed clients to choose from items such as televisions, stereos, and DVD players. The number of chips a participant was permitted to draw was determined on a schedule that was responsive to test outcomes.
CM systems using vouchers have not been directly compared with CM systems that use prizes.
The prize-based CM system is used in addition to intensive outpatient substance abuse treatment program services in community treatment clinics. The target population is adult patients who primarily abuse stimulants (such as cocaine) or opioids (such as heroin) or who may have multiple substance abuse problems.
18 to 100
Quality of Life Inventory Total Scores (QOLI)
Petry, Alessi, and Hanson (2007) found that Quality of Life Inventory (QOLI) total scores increased significantly over time for study participants who received contingency management. The total scores did not increase significantly for study participants who received standard care. Looking at the subscale scores, Civic Action, Home, Relationship with Relatives, Self-Regard, Standard of Living, and Work scores significantly increased over time for the CM group. These scores generally remained unchanged in the standard care group. For the Love Relationships subscale, the scores significantly decreased for the standard care group.
The number of scales that participants rated as at least important was greater in the CM group compared with the standard care group at the month 9 assessment. However, there were no significant differences between the groups at the remaining assessment periods.
Longest Duration of Abstinence (LDA)
The analysis of the relationship between CM and LDA found that group assignment (CM versus standard care) made a significant impact on LDA. Standard care group members achieved 3.5 weeks (± 3 weeks) of abstinence, compared with 5.8 weeks (± 4.5 weeks) for those in the CM group. The final step of this analysis found that LDA was a significant predictor of changes in QOLI scores over time, indicating that LDA at least partially mediates the relationship between type of treatment and changes over time in QOLI scores.
Petry and colleagues (2005) found that participants randomly assigned to the incentive condition were significantly more likely to be retained than those assigned to receive usual care. By the end of 12 weeks, 49 percent of participants in the incentive condition were still retained, compared with 35 percent of the usual care participants. Incentive participants were also more likely to submit weekly samples than usual care participants.
Participants in the incentive group attended an average of 19.2 counseling sessions (± 16.8 sessions) during the 12-week study period, compared with 15.7 counseling sessions (± 14.4 sessions) attended by participants who received usual care.
The general estimating equation analysis (which assumed that missing samples were negative if they were preceded and followed by negative samples) showed nonsignificant differences between the incentive group and usual care group in terms of urine samples free of the primary and secondary target drugs. General estimating equation analysis (which coded missing samples as positive) showed a significantly higher proportion of stimulant-free samples in the incentive group. Most urine samples were stimulant free in both conditions. The rates of negative alcohol breath samples were also extremely high for both groups. Rates did not differ by condition, except when missing data was treated as positive.
Analysis of LDA measures showed that the usual care group had an average number of 5.2 visits with confirmed abstinence (± 6.9 visits) and the incentive group had an average number of 8.6 visits with confirmed abstinence (± 9.2 visits). This translated into roughly 2.6 weeks of consecutive abstinence for the usual care group and 4.4 weeks for the incentive group. The incentive group had about twice as many participants with at least 4 weeks and 8 weeks of documented sustained abstinence. The percentage of participants with 12 weeks of documented abstinence was nearly four times as great for the incentive group as for the usual care participants.
Negative Samples Submitted
The proportion of participants who had very good outcomes (19 to 24 negative samples of stimulants and alcohol) was significantly higher in the incentive group than in the usual care group. Conversely, the proportion with relatively poor outcomes (one to six negative samples) was lower in the incentive group than in the usual care group.