Effectiveness of contingency management using transdermal alcohol monitoring to reduce heavy drinking among driving while intoxicated (DWI) arrestees: A randomized controlled trial

Background: Driving while intoxicated (DWI) is a serious public health problem. However, treatment for DWI arrestees is not readily available. This study examines the effectiveness of a contingency management (CM) procedure using transdermal alcohol concentration (TAC) monitoring to reduce drinking among DWI arrestees. Method: The study participants were 216 DWI arrestees under pretrial and included both Mandated participants undergoing court-ordered TAC monitoring and Non-Mandated participants wearing a study-provided TAC monitor. Participants were randomly assigned to either a CM (Mandated = 35; Non-Mandated = 74) or a Control condition (Mandated = 37; Non-Mandated = 70) and completed the 8-week intervention. CM participants received $50/week for not exceeding a TAC of 0.02 g/dL during the previous week. Payments to Controls were yoked to the CM group. Results: Among Non-Mandated participants, the probability of meeting the contingency was higher and remained stable (about 65%) over time in the CM group, whereas the probability was lower and declined in the Control group, widening the gaps in the probability between the study conditions (16.7%-24.1% greater in the CM group from visit 4 to 8, all p < 0.05). Among Mandated participants, the probability was not significantly different between conditions (p = 0.06-0.95). Furthermore, among Non-Mandated participants, the percentage of heavy drinking days remained low (9.16%-11.37%) in the CM group, whereas it was greater and increased over time (17.43%-26.59%) in the Control group. In Mandated participants, no significant differences in percent heavy drinking days were observed between conditions (p = 0.07-0.10). Conclusion: We found that contingency effects on alcohol use are more pronounced among frequent and heavy alcohol users, i.e., Non-Mandated DWI arrestees. However, for individuals whose drinking was already suppressed by existing contingencies (i.e., court-mandated TAC monitoring), our CM procedure did not produce additional reductions in drinking.