Background

Cocaine dependence remains an intractable U.S. public health problem that contributes to many of our most disturbing social problems, including the spread of infectious disease (e.g., HIV, hepatitis, tuberculosis), crime, violence, poverty, traumatic injuries, and neonatal drug exposure. Although the overall number of cocaine users has decreased during the past decade, the number of heavy users (once a week or more) has increased, along with other disturbing trends such as increases in the number of cocaine-related emergency-room admissions, deaths, and admissions to State-supported treatment facilities.

There is no consensus on how to treat cocaine dependence. No pharmacotherapy is available, but even if one should be developed, effective psychosocial treatments would still be necessary to address the multiple problems common in this population. Research on psychosocial treatments for cocaine dependence has been relatively fruitful, and several effective treatments have been reported (Carroll et al. 1991, 1994a,b; Higgins et al. 1991, 1993a, 1994a, 1995.)

One such intervention, CRA + Vouchers, is the focus of this manual. This treatment integrates a community reinforcement approach (CRA), originally developed as an effective treatment for alcohol dependence (Myers and Smith 1995), with an incentive program (Vouchers) wherein patients can earn points exchangeable for retail items by remaining in treatment and cocaine abstinent. This multicomponent treatment as a whole and several of its components have been demonstrated to be efficacious in controlled clinical trials conducted with cocaine-dependent adults in outpatient clinics. Its applicability to younger individuals and in other settings has not been tested.

This manual provides the necessary guidance for therapists to implement CRA + Vouchers as a whole as well as the individual components that are effective as adjuncts to other treatments.

Our group has conducted five controlled clinical trials examining the efficacy of CRA + Vouchers. In two trials, CRA + Vouchers was superior to standard drug abuse counseling in retaining patients in treatment and documenting clinically significant periods of continuous cocaine abstinence (Higgins et al. 1991, 1993a). For example, in a 24-week study, more than 75 percent of those who received CRA + Vouchers completed 24 weeks of outpatient treatment compared to only 11 percent of patients who received drug abuse counseling. Several months of continuous cocaine abstinence were documented in the majority of patients treated with CRA + Vouchers versus only 10 percent among those treated in a standard counseling group.

A third trial further assessed the reliability of the positive outcomes observed with CRA + Vouchers and began to identify which of its several components were clinically active (Higgins et al. 1994a). A 24-week, randomized trial was conducted to assess the efficacy of the vouchers component. Cocaine-dependent outpatients were randomly assigned to receive CRA + Vouchers or CRA alone. Patients who received CRA + Vouchers stayed in treatment significantly longer and achieved greater durations of continuous cocaine abstinence than patients assigned to CRA alone. A fourth clinical trial was recently completed in our clinic, further supporting the efficacy of the voucher program in promoting sustained periods of cocaine abstinence among patients enrolled in outpatient care.

Another component, wherein patients' significant others were used to provide social reinforcement when the patient successfully abstained from cocaine abuse, was recently tested. Preliminary research suggested that this was an effective intervention (Higgins et al. 1994b). However, a randomized clinical study yielded no evidence to support the efficacy of this approach, and it was discontinued.

In two of the trials with positive outcomes, followup assessments were conducted 12 months after treatment entry. In each trial, evidence supported the greater efficacy of the complete treatment package (CRA + Vouchers) compared to drug abuse counseling or CRA alone (Higgins et al. 1995). For cocaine-dependent adults, the efficacy of incentives for remaining in treatment and for providing objective evidence of recent cocaine abstinence has received further scientific support. In a recent review of the scientific literature, 11 of the 13 studies (85 percent) on the use of incentives in the treatment of cocaine dependence showed positive treatment effects (Higgins 1996).

Use With Other Populations

CRA + Vouchers was developed and tested in Burlington, Vermont, a small metropolitan area. To assess the generality of this treatment approach to large metropolitan areas, additional trials were conducted in methadone-maintenance clinics located in Baltimore and San Francisco with patients who abused cocaine while in treatment for opioid dependence (Silverman et al. 1996a; Tusel et al. 1995).

Only the voucher program was examined in these 3-month randomized trials. Vouchers significantly increased cocaine and other drug abstinence, thereby demonstrating the applicability of incentives for reducing cocaine abuse to abusers residing in large metropolitan areas.

Several recent adaptations of the voucher program for use with special populations also appear promising. One application was with schizophrenic cocaine abusers (Shaner et al. 1997). Another involves the use of the voucher program to increase treatment retention, abstinence, and participation in prenatal and postnatal care among pregnant and postpartum cocaine-abusing women (Kirby et al. in press).

Concurrent Alcohol Dependence

We were surprised to learn that approximately 60 percent of our patients were also alcohol dependent. Disulfiram (Antabuse) therapy, with clinic or family supervision to assure medication compliance, is a standard component of CRA with alcoholics. Thus, we quickly adopted the practice for simultaneously treating alcohol and cocaine dependence in these dually dependent patients. In a chart review of these patients, disulfiram therapy was associated with significant decreases in drinking and, unexpectedly, cocaine use as well (Higgins et al. 1993b).

Carroll and colleagues subsequently reported results consistent with these findings in a pilot clinical trial (Carroll et al. 1993). In that study, disulfiram therapy was compared to naltrexone therapy in a population of outpatients who abused cocaine and alcohol. Patients were randomized to receive one of the two medications as an adjunct to once-weekly psychotherapy. Disulfiram therapy resulted in reductions in drinking and cocaine use that were three or more times greater than those with naltrexone therapy. A larger, randomized trial on the efficacy of disulfiram therapy in patients who abuse cocaine and alcohol was completed recently by this same group and again, cocaine use was significantly reduced via disulfiram therapy (Carroll, personal communication).