Effects of time-based administration of abstinence reinforcement targeting opiate and cocaine use

Abstract

Polydrug use is a common problem among patients in opioid-substitution treatment. Polydrug use has been reduced by administering abstinence-reinforcement contingencies in a sequence, such that a single drug is targeted until abstinence is achieved, and then an additional drug is targeted. The present study examined effects of administering abstinence-reinforcement contingencies sequentially based on time rather than on achieved abstinence. Participants accessed paid work (about $10/hr maximum) in the Therapeutic Workplace by providing urine samples 3 times per week. The urine samples were tested for opiates and cocaine. During an induction period, participants earned maximum pay independent of drug abstinence. Then, maximum pay depended upon urine samples that were negative for opiates. Two weeks later, maximum pay depended upon urine samples that were negative for both opiates and cocaine. Opiate and cocaine abstinence increased following administration of the respective contingencies. The time-based administration of abstinence reinforcement increased opiate and cocaine abstinence.

Keywords: abstinence reinforcement; contingency management; drug addiction; incentives; therapeutic workplace.

Figure 1.

Consort flowchart showing the enrollment of participants (top) and the classification of participants for purposes of data analysis (bottom).

Figure 2.

Urinalysis results across consecutive mandatory urine samples for Completers (n = 91). Each participant is represented by a row of symbols. The symbols shown in each row represent samples that were negative for both opiates and cocaine (filled squares), negative for opiates and positive for cocaine (gray squares), positive for opiates and negative for cocaine (gray triangles), positive for both opiates and cocaine (unfilled triangles), missing (blank), or excused (“e”). Phase lines represent the administration of each abstinence-reinforcement contingency.

Figure 3.

The percentage of urine samples that were negative for opiates for Opiate Users (top, n = 57) and cocaine for Opiate-Abstinent Cocaine Users (bottom, n = 25) as judged by the missing-positive analysis in the six consecutive mandatory urine samples before and after each contingency was administered. Dots show the mean across participants in each sample and the dashed lines show the mean aggregated across the six samples.

Figure 4.

The percentage of urine samples that were negative for opiates (left) and cocaine (right) aggregated, for each participant, over the six consecutive mandatory urine samples before and after the contingency targeting each drug was administered for Opiate Users (left, n = 57) and Opiate-Abstinent Cocaine Users (right, n = 25), as judged by the missing-positive analysis. Dots show percentages for individual participants and bars show the mean across participants. Asterisks show comparisons that were statically significant as judged by Wilcoxon matched-pairs signed-ranks tests at the p < .001 (***) level.

Figure 5.

The mean percentage of urine samples that tested negative for opiates (left) and cocaine (right) aggregated across all urine samples before (unfilled) and after (filled) the contingencies targeting abstinence from opiates (left; Opiate Users; n = 57) and cocaine (right; Opiate-Abstinent Cocaine Users; n = 25) were administered. Results from the missing-positive analysis are shown for each participant, and participant labels are consistent with those used in Figure 2. Arrows show changes in abstinence.