Objectives: This systematic review is aimed at gaining an overall picture on the respective effects of prescription of methadone vs. heroin and other substances. Search strategy: Six databases (Medline, Campbell Crime and Justice Group, National Criminal Justice Reference Service, National Treatment Agency for Substance Misuse, JSTOR and Criminal Justice Abstracts) as well as relevant journals and websites (Harm reduction Journal, Journal of Substance Abuse Treatment, Drug and Alcohol Dependence, Drug and Alcohol Review, Drug and Therapeutics Bulletin, International Journal of Drug Policy, Journal of Clinical Psychopharmacology, éviance et Société, Criminal Justice and Behavior, Criminologie, www.heroinstudie.de and www.drugscope.org.uk) have been searched for relevant studies meeting the inclusion criteria.
Selection Criteria: To be eligible, studies had to assess the effects of any substitution therapy (using .g. methadone and/or opiates as substitution drugs). Only effects on offending have been considered. Comparisons of competing treatments (substitution therapy vs. any other form of treatment, including placebo treatment or no treatment at all) were restricted to studies meeting level 4 or higher on the scale developed by Sherman et al. (1997). In addition, one-group pre-post evaluations of substitution therapies were included because changes in offending are substantial compared to pre-treatment levels, while comparisons of treatment with several substances often show modest differences. Finally, studies that assessed the impact of drug substitution at the macro (i.e. city or regional) level were also included. The three different types of studies have been analyzed separately.
Data Collection and Analysis: 66 studies were considered, and 46 were selected for inclusion in the review. They separately assess the impact of methadone, buprenorphine, heroin, naltrexone, dihydrocodeine or Levo-alpha-acetylmethadone substitution on the criminal behaviour of opiates addicts. Meta-analytic techniques were used to identify overall effects of several substances. Comparisons of different treatments (i.e. substitution vs. any other treatment) were restricted to studies meeting levels 4 or 5 on the scale developed by Sherman et al. (1997).
Main Results: Heroin maintenance reduces crime significantly more than Methadone maintenance. Methadone maintenance reduces offending more than treatments without substitution therapy, but the mean effect size is not significant (p >.1). However, very large (and significant) reductions in criminal behaviour are observed during methadone maintenance therapy with respect to pre-treatment levels. Buprenorphine does not significantly reduce criminal behaviour, although effects are positive, be it with respect to methadone or a placebo. Naltrexone treatment reduces criminality significantly more than behaviour therapy or counselling.
Conclusion: Heroin maintenance has been found to significantly reduce criminal involvement among treated subjects, and it is more effective in crime reduction than methadone maintenance. Methadone maintenance greatly reduces criminal involvement, but apparently not significantly more so than other interventions. Buprenorphine and Naltrexone have been found to be promising, although few studies have been identified using these substances in maintenance treatment.