DYNAMICS IN THE COSTS OF CRIMINALITY AMONG OPIOID DEPENDENT INDIVIDUALS

   Purpose: Research into crime-related costs associated with methadone maintenance treatment's (MMT) known longitudinal pattern of continued drug use, treatment and full abstention is sparse. Our objective was to characterize crime-related costs associated with this chronic cyclical pattern among opioid dependent individuals.

   Methods: We considered individuals enrolled in a prospective study between December 2011 and May 2013 in Vancouver, Canada. Monthly crime-related costs (2013 CAD) were derived from self-reported criminal activity. On the basis of MMT receipt and illicit opioid use, individuals were classified in mutually exclusive health states: (i) MMT with high effectiveness; (ii) MMT with low effectiveness; (iii) opioid abstinence; or (iv) relapse. MMT was defined as with high effectiveness if no concurrent illicit opioid use was reported, and as with low effectiveness otherwise. We stratified individuals as daily, non-daily or non-stimulant users and controlled for individual demographic and socio-economic characteristics. A two-part multiple regression model, estimated using generalized linear modeling, was constructed to account for excess zeroes and skewness in cost data. The first part modeled the probability of having a non-zero cost using a logit model specification, while the second estimated the level of non-zero costs, using a Gamma distribution and log link. Crime-related costs were estimated for each health state and stratified by stimulant use intensity.

   Results: Our study included 982 individuals (median age 47, 38% female) for a total of 2,232 observations. Compared to periods of relapse, MMT with high effectiveness was associated with lower monthly costs of criminality ($6,298 reduction; 95% C.I. ($1,578,$11,017)), as were episodes of opioid abstinence ($6,563 ($1,564,$11,561)). Also compared to periods of relapse, estimated cost reductions for daily stimulant users were greater than for non-daily users, both for periods of MMT with high effectiveness ($12,203 [$2,541,$21,866] vs.$3,832 [$938,$6,725]) and periods of opioid abstinence ($12,704 [$2,453,$22,954] vs.$3,998 [$1,024,$8,061]).

   Conclusions: Using longitudinal data on individuals with a history of MMT utilization, we found that MMT with high effectiveness was associated with lower costs of criminality. When compared to periods of relapse, cost reductions were highest among daily stimulant users during periods of MMT with high effectiveness or during periods of opioid abstinence, whereas periods of MMT with low effectiveness compared to periods of relapse were not associated with any statistical difference in costs.