Cocaine withdrawal severity and urine toxicology results from treatment entry predict outcome in medication trials for cocaine dependence

Abstract

Both cocaine withdrawal symptoms, measured by an instrument called the Cocaine Selective Severity Assessment (CSSA), and urine toxicology results obtained at the start of treatment have been shown to predict treatment outcome in outpatient cocaine dependence treatment. This study further evaluates the predictive validity of the CSSA and urine toxicology results, alone and in combination. Subjects included 76 cocaine-dependent individuals who participated in 7-week, outpatient, pilot medication trials for cocaine dependence. Predictor variables included CSSA scores and results from a urine toxicology screen obtained on the first day of medication treatment. Successful outcome was defined as 3 continuous weeks of self-reported abstinence from cocaine confirmed by urine toxicology screens. Predictive validity was assessed by logistic regression analysis. Both the urine toxicology screen and the CSSA scores were significant predictors of 3 weeks of continuous abstinence from cocaine, and the inclusion of both variables significantly improved the predictive validity of either variable alone. Urine toxicology results and CSSA scores obtained at treatment entry are useful predictors of outcome in outpatient cocaine dependence treatment.

Introduction

Early treatment failure continues to be a major problem in the treatment of cocaine dependence. High dropout rates and failure to attain significant periods of abstinence are common occurrences Alterman et al., 1996, Carroll et al., 1991, Carroll et al., 1994, Kampman et al., 1999, Kang et al., 1991, Means et al., 1989. The ability to identify patients who are likely to respond poorly to standard treatment would be useful for a number of reasons. First, it would allow treatment providers to reserve more intensive (and more expensive) treatment modalities for those patients who need them. For researchers, the ability to identify treatment-resistant patients would help them to better understand the specific characteristics of these patients that may contribute to their poor performance in treatment. It would also allow researchers to better select patient populations in which to study new interventions.

Recently, two variables have been found to be predictive of outcome in outpatient cocaine dependence treatment: the severity of cocaine withdrawal symptoms and a urine toxicology screen positive for cocaine metabolites at the start of treatment. Alterman et al. (1996) attempted to identify predictors of treatment completion in a day hospital program. Out of a wide range of predictor variables, including demographics, drug use data, Addiction Severity Index (ASI) data, psychiatric diagnoses, and Symptom Checklist 90 (SCL 90) scores, only urine toxicology results at intake and log-transformed self-reported days of cocaine use in the month prior to treatment were significant predictors of treatment completion (Alterman et al., 1996). Specifically, only 36% of patients with a urine toxicology screen positive for cocaine metabolites at intake completed treatment, whereas 73% of patients with a negative urine toxicology screen completed treatment.

In three other studies Kampman, 1998, Kampman et al., 2001, Mulvaney et al., 1999, it was found that the presence of more severe cocaine withdrawal symptoms at the start of treatment was a predictor of poor treatment outcome. In the initial validity testing of an instrument designed to measure cocaine withdrawal symptoms called the Cocaine Selective Severity Assessment (CSSA), Kampman et al. (1998) found that scores on the CSSA correlated strongly with dropout in the first week of treatment. The study by Mulvaney et al. (1999) retrospectively evaluated the combined ability of the CSSA and initial urine toxicology screens to predict treatment attrition and the ability to attain abstinence in the first month of treatment. In 87 cocaine-dependent outpatients, both the initial urine toxicology screen and cocaine withdrawal symptoms predicted treatment outcome (Mulvaney et al., 1999). Cocaine-dependent patients with more severe cocaine withdrawal symptoms (high CSSA scores) were five times more likely to drop out of treatment in the first 30 days than were patients with less severe cocaine withdrawal symptoms (low CSSA scores). Patients with high scores on the CSSA were also four times less likely to attain abstinence from cocaine in the first month of treatment measured by submission of three consecutive urine toxicology screens in a week. Urine toxicology results were also predictive of outcome in this study. Patients with a positive urine toxicology screen at the start of treatment were twice as likely to drop out and three times less likely to attain abstinence than were patients with a negative initial urine toxicology screen. Most recently, CSSA scores and a urine toxicology screen obtained early in treatment predicted attrition in a VA-sponsored day hospital (Kampman et al., 2001). In this trial, high scores on the CSSA at intake screening predicted dropout in a 4-week day hospital program. Likewise, a urine toxicology screen positive for cocaine metabolites on the first day of the day program also predicted dropout.

The current trial further evaluates and expands our understanding of the separate and combined predictive ability of cocaine withdrawal symptoms, measured by the CSSA, and a urine toxicology screen obtained at treatment entry. In this trial, we examined the ability of these predictor variables to predict outcome in a longer 7-week trial. In addition, as an outcome measure, we used 3 weeks of continuous abstinence from cocaine verified by urine toxicology screens. This is a more clinically valid measure of treatment success. The ability of cocaine-dependent patients to achieve 3–4 weeks of continuous abstinence from cocaine at the beginning of treatment has been shown to be predictive of abstinence from cocaine 6 months later Carroll et al., 1994, Kosten et al., 1992.