Transdermal alcohol concentration data collected during a contingency management program to reduce at-risk drinking

Highlights

• Financial reinforcement for reduced heavy drinking was successful for 12 weeks.

• Contingencies based on transdermal alcohol concentration increased the number of no drinking days in heavy drinkers.

• Heavy drinking was reduced in non-treatment-seeking heavy drinkers.

• Transdermal alcohol monitoring has utility in contingency management procedures.

Abstract

Background

Recently, we demonstrated that transdermal alcohol monitors could be used in a contingency management procedure to reduce problematic drinking; the frequency of self-reported heavy/moderate drinking days decreased and days of no to low drinking increased. These effects persisted for three months after intervention. In the current report, we used the transdermal alcohol concentration (TAC) data collected prior to and during the contingency management procedure to provide a detailed characterization of objectively measured alcohol use.

Methods

Drinkers (n = 80) who frequently engaged in risky drinking behaviors were recruited and participated in three study phases: a 4-week Observation phase where participants drank as usual; a 12-week Contingency Management phase where participants received $50 each week when TAC did not exceed 0.03 g/dl; and a 3-month Follow-up phase where self-reported alcohol consumption was monitored. Transdermal monitors were worn during the first two phases, where each week they recived $105 for visiting the clinic and wearing the monitor. Outcomes focused on using TAC data to objectively characterize drinking and were used to classify drinking levels as either no, low, moderate, or heavy drinking as a function of weeks and day of week.

Results

Compared to the Observation phase, TAC data indicated that episodes of heavy drinking days during the Contingency Management phase were reduced and episodes of no drinking and low to moderate drinking increased.

Conclusions

These results lend further support for linking transdermal alcohol monitoring with contingency management interventions. Collectively, studies to date indicate that interventions like these may be useful for both abstinence and moderation-based programs.

Introduction

Recent advances in technology have improved the ability to objectively monitor alcohol use. Transdermal alcohol monitoring devices such as the Secure Continuous Remote Alcohol Monitor [SCRAM-II™, Alcohol Monitoring Systems Inc. (AMS), Highlands Ranch, CO] provide a real-time measure (every 30 min, 24 h a day) of alcohol excreted through the skin (Swift, 2000, Swift, 2003). This transdermal alcohol concentration (TAC) data can then be used to estimate both breath alcohol levels and quantity of alcohol consumed as well as identify patterns of alcohol consumption (Dougherty et al., 2012, Hill-Kapturczak et al., 2015).

Recent research has sought to test the feasibility and effectiveness of using transdermal alcohol monitors in contingency management interventions to reduce or eliminate alcohol consumption (Barnett et al., 2011, Dougherty et al., 2014a). Contingency management interventions are based on operant conditioning principles whereby individuals receive reinforcers (e.g., money or vouchers) when treatment goals such as abstinence or moderation of substance use are achieved (Higgins et al., 1994, Stitzer et al., 1980, Stitzer and Petry, 2006). This approach has been shown to be an effective intervention for a variety of substances (reviewed in Prendergast et al., 2006, Roll et al., 2006). Because contingency management requires the use of real and important consequences to reinforce abstinence or reduced drug use, it requires an objective measure of drug use that will be unbiased by self-report and identify levels of drinking. With other drugs of abuse (e.g., cocaine, opaites, marijuana), contingency management interventions have been possible through the use of urine-drug screen testing (Markway and Baker, 2011). In contrast to other drugs of abuse, biological markers for identifying alcohol use are not as straightforward for the use of financial contingencies.

Current alcohol use detection methods are typically a combination of self-report and alcohol use biomarkers. Self-reported alcohol use often underestimates drinking in real-world settings due to memory impairment, poor insight, or an unwillingness to self-report (de Visser and Birch, 2012, Devos-Comby and Lange, 2008, Kerr and Stockwell, 2012, May and Gossage, 2011, Sobell and Sobell, 2003, White et al., 2003). In the context of contingency management, financial motivation would be expected to make self-report especially vulnerable to inaccurate under-reporting of drinking. Clinical interventions often rely on self-report measures, but there is a definite move toward and increased reliance upon other alcohol use biomarkers (e.g., Anton et al., 2002, Kranzler et al., 2004, Mann et al., 2013, Pettinati et al., 2010) to objectively detect alcohol use.

However, biomarkers can be unreliable indicators of alcohol use. For example, non-specific alcohol use markers [e.g., γ-glutamyltransferase (GGT) or carbohydrate deficient transferrin (CDT)] measured in blood have long half-lives (weeks to months), but they are only reliable at detecting heavy drinking and may provide false positive results (reviewed in Javors and Johnson, 2003, Maenhout et al., 2013, Muñiz-Hernández et al., 2014)]. For example, increased serum GGT or CDT levels can occur in conditions not related to alcohol use. In the case of GGT, these conditions include obesity, diabetes, hypertension, hypertriglyceridemia, and non-alcoholic liver disease (reviewed in Muñiz-Hernández et al., 2014). In the case of CDT alternative causes for increases include phosphomannose isomerase deficiency, genetic transferrin variants, untreated galactosemia, hereditary fructose intolerance, and pregnancy (reviewed in Helander et al., 2014). In contrast, direct markers (e.g., ethanol or the ethanol metabolites ethyl-glucuronide and phosphatidylethanol) while specific for alcohol, have shorter half-lives (hours to weeks) which limit the window of detection (reviewed in Javors and Johnson, 2003, Maenhout et al., 2013). However, transdermal alcohol monitoring provides a continuous, objective measure of alcohol use which has the ability to detect different levels of drinking (i.e., no, low, moderate, and heavy; Dougherty et al., 2014a). As such, transdermal alcohol monitoring offers a new level of analysis for interventional studies and may even be used in the intervention itself. With the development of minimally invasive transdermal alcohol monitoring procedures, contingency management has only recently been validated as a possible intervention to moderate or control alcohol consumption.

There have been two preliminary studies that have used transdermal alcohol monitoring to implement contingency management designed to reduce alcohol use (Barnett et al., 2011, Dougherty et al., 2014a). The first study, conducted by Barnett and colleagues (2011), used transdermal alcohol monitors in a 2-week contingency management intervention to achieve abstinence. They demonstrated that financial contingencies did reduce the frequency of heavy drinking among a small sample of heavy drinkers (n = 13) across a 2-week period. However, these reductions were achieved primarily through increased abstinence and there was no evidence for reduced levels of drinking when drinking occurred. In the second study, we (Dougherty et al., 2014a) used transdermal alcohol monitors in an 8-week contingency management intervention designed to moderate alcohol consumption among a group of non-treatment seeking drinkers (n = 26) who frequently engaged in at-risk drinking (as defined by NIAAA, 2010). Instead of using an abstinence criteria, our study used transdermal alcohol monitoring to reinforce lower-level or less harmful patterns of drinking. More specifically, the contingency intervention provided monetary incentives each week when transdermal alcohol concentrations did not exceed 0.03 g/dl (i.e., approximately one or two standard drinks) on any day of the week. Not only did participants decrease their frequency of any drinking, but the amount of alcohol consumed per drinking episode also decreased – most importantly, this included reductions in heavy weekend binge drinking. During the course of this latter study, it became apparent that transdermal alcohol monitors can be used not only to dichotomously define whether or not any drinking occurred, but also to characterize levels of consumption defined as no, low, moderate, or heavy drinking. Together, these two preliminary studies indicate that transdermal alcohol monitors can be used to contingently reduce drinking, but also to moderate the amount of alcohol use.

More recently, we have shown in a 12-week contingency management study that self-reported problematic levels of drinking could be reduced to safer levels among a large group (n = 80) of at-risk heavy drinkers (Dougherty et al., 2014b). That publication focused on the self-reported drinking observed using standard calendar-based methods of Timeline Followback interview (Sobell and Sobell, 1992). However, the contingency was actually implemented using TAC readings to reinforce non-heavy drinking patterns; it is important to understand exactly what the strictly objective observations of TAC data will tell us about drinking behavior. The present report now presents the completed analyses of the TAC outcome data collected during the study. Specifically, we use the TAC data collected during transdermal alcohol monitoring to objectively characterize the patterns of alcohol use (no, low, moderate, and heavy drinking days) during the 4-week observation phase that preceded contingency management and then throughout the 12-week contingency management phase.