The effectiveness of diversion programmes for offenders using Class A drugs: a systematic review and meta-analysis

Background and Aims: Community-based offenders are an under-researched group. We reviewed existing literature for evidence on the effectiveness of community-based diversion programmes for Class A drug-using offenders. Methods: 31 databases, online resources and bibliographies were searched for studies published 1985 to 2012, with an update search March 2016. No geographic restrictions were applied although only English language papers were considered. Included studies involved community-based Criminal Justice System diversion of Class A drug users via voluntary or court-mandated treatment services. Results: 16 studies were initially included from the US (10), UK (4), Canada (1), Australia (1). In a meta-analysis, there was evidence for a small impact of diversion to treatment on drug use reduction (for primary Class A drug use: OR random effects 1.68, CI 1.12-2.53, and use of other drugs: OR random effects 2.60, 1.70-3.98). Class A drug users were less likely to complete treatment (OR random effects 0.90, 0.87-0.94) than users of other drugs. There was uncertainty surrounding results for offending, which were not pooled due to lack of comparability of outcome measures and heterogeneity. Individually, studies pointed to a minor effect of diversion on offending. Findings remained unchanged following an update review (March 2016: US [3], Australia [1]). Conclusions: Treatment accessed via community-based diversion schemes is effective at reducing drug use in Class A drug-using offenders. Evidence of a reduction in offending as a result of diversion schemes for Class A drug users is uncertain. Poor methodological quality and data being largely limited to US methamphetamine users limits the evidence available. Further research is needed to determine whether diversion is effective in settings outside the US and which drug-using offenders may benefit.