The influence of baseline marijuana use on treatment of cocaine dependence: application of an informative-priors Bayesian approach.

Autor: Charles eGreen, Joy eSchmitz, Jan eLindsay, Claudia ePedroza, Scott D. Lane, Rob eAgnelli, Kimberly eKjome, F Gerard Moeller
Jazyk: angličtina
Rok vydání: 2012
Předmět:
Zdroj: Frontiers in Psychiatry, Vol 3 (2012)
Druh dokumentu: article
ISSN: 1664-0640
DOI: 10.3389/fpsyt.2012.00092
Popis: Background: Marijuana use is prevalent among patients with cocaine dependence and often non-exclusionary in clinical trials of potential cocaine medications. The dual-focus of this study was to (1) examine the moderating effect of baseline marijuana use on response to treatment with levodopa/carbidopa for cocaine dependence; and (2) apply an informative-priors, Bayesian approach for estimating the probability of a subgroup-by-treatment interaction effect.Method: A secondary data analysis of two previously published, double-blind, randomized controlled trials provided samples for the historical dataset (Study 1: N = 64 complete observations) and current dataset (Study 2: N = 113 complete observations). Negative binomial regression evaluated Treatment Effectiveness Scores (TES) as a function of medication condition (levodopa/carbidopa, placebo), baseline marijuana use (days in past 30), and their interaction. Results: Bayesian analysis indicated that there was a 96% chance that baseline marijuana use predicts differential response to treatment with levodopa/carbidopa. Simple effects indicated that among participants receiving levodopa/carbidopa the probability that baseline marijuana confers harm in terms of reducing TES was 0.981; whereas the probability that marijuana confers harm within the placebo condition was 0.163. For every additional day of marijuana use reported at baseline, participants in the levodopa/carbidopa condition demonstrated a 5.4% decrease in TES; while participants in the placebo condition demonstrated a 4.9% increase in TES.Conclusion: The potential moderating effect of marijuana on cocaine treatment response should be considered in future trial designs. Applying Bayesian subgroup analysis proved informative in characterizing this patient-treatment interaction effect.
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