The Relationship Between Early-Phase Substance-Use Trajectories and Drug Court Outcomes
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This study sought to identify patterns of substance use among 1,019 participants of the New South Wales Drug Court program (Sydney, Australia) between 2003 and 2009. Group-based trajectory modeling identified five groups of participants: compliant participants (24.4%), who had a near-zero probability of returning a positive urine test at each occasion; responding participants (25.3%), for whom the probability of returning a positive test decreased; relapsing participants (14.1%), for whom the probability of returning a positive test increased; mid-level chronic participants (26.0%), who had a one in two chance of returning a positive test at each episode; and a high-level chronic group (10.2%), who had a very high probability of returning a positive test at each episode. Group membership probability was found to be a good predictor of treatment and criminal justice outcomes. The challenge for future research is to identify the characteristics that explain these early-phase substance use trajectories.