Sarra L Hedden | PubMed Health

PubMed2006

Characteristics of cocaine- and marijuana-dependent subjects presenting for medication treatment trials.

Evaluation of the characteristics of individuals presenting for substance abuse treatment can provide important information to help focus treatment services. In this study, demographic and clinical characteristics of individuals presenting for medication trials for the treatment of cocaine or marijuana dependence were compared. Marijuana-dependent subjects were generally younger than cocaine-dependent subjects, more likely to be Caucasian, and completed more years of education. Marijuana-dependent subjects also reported significantly more days using than cocaine-dependent subjects, as well as higher levels of craving. Some differences in psychiatric symptomatology were also noted, with cocaine-dependent subjects more likely to report anxiety symptoms and marijuana-dependent subjects reporting more past depressive episodes. Past and current other drug use was similar between the two groups. These results highlight the significant impairments associated with marijuana and cocaine dependence.

Adult↗

PubMed2006

Randomization in substance abuse clinical trials.

BACKGROUND: A well designed randomized clinical trial rates as the highest level of evidence for a particular intervention's efficacy. Randomization, a fundamental feature of clinical trials design, is a process invoking the use of probability to assign treatment interventions to patients. In general, randomization techniques pursue the goal of providing objectivity to the assignment of treatments, while at the same time balancing for treatment assignment totals and covariate distributions. Numerous randomization techniques, each with varying properties of randomness and balance, are suggested in the statistical literature. This paper reviews common randomization techniques often used in substance abuse research and an application from a National Institute on Drug Abuse (NIDA)-funded clinical trial in substance abuse is used to illustrate several choices an investigator faces when designing a clinical trial. RESULTS: Comparisons and contrasts of randomization schemes are provided with respect to deterministic and balancing properties. Specifically, Monte Carlo simulation is used to explore the balancing nature of randomization techniques for moderately sized clinical trials. Results demonstrate large treatment imbalance for complete randomization with less imbalance for the urn or adaptive scheme. The urn and adaptive randomization methods display smaller treatment imbalance as demonstrated by the low variability of treatment allocation imbalance. For all randomization schemes, covariate imbalance between treatment arms was small with little variation between adaptive schemes, stratified schemes and unstratified schemes given that sample sizes were moderate to large. CONCLUSION: We develop this paper with the goal of reminding substance abuse researchers of the broad array of randomization options available for clinical trial designs. There may be too quick a tendency for substance abuse researchers to implement the fashionable urn randomization schemes and other highly adaptive designs. In many instances, simple or blocked randomization with stratification on a major covariate or two will accomplish the same objectives as an urn or adaptive design, and it can do so with more simply implemented schedules and without the dangers of overmatching. Furthermore, the proper analysis, fully accounting for the stratified design, can be conducted.

Humans↗