6 August 2019

Methadone and buprenorphine, medications used to treat opioid dependence, are associated with a significant reduction in crime rates and staying in treatment is key, according to a new study by researchers from the National Drug and Alcohol Research Centre (NDARC) at UNSW Sydney, Australia, and the University of Bristol, UK.

The observational retrospective study published in Lancet Public Health, investigated the effectiveness of opioid agonist treatment (OAT), specifically methadone and buprenorphine, on crime rates in New South Wales (NSW), Australia. 

The unique study design linked data on treatment episodes, criminal charges and mortality for 10,744 people entering OAT for the first time in NSW between 2004 and 2010.

The study comprehensively examined the potential effect of OAT on criminal charge rates, considering various time periods within an OAT episode and varying patterns of engagement in OAT across treatment episodes and episode lengths.

Most people in the study cohort were male (71 per cent) and non-Indigenous (77 per cent), with a median age of 29. In the four years before treatment entry, 60 per cent had previously been charged with a criminal offence and 36 per cent had been in prison.

Staying in treatment continuously, rather than cycling in and out of treatment, was associated with reduced criminal offending. Being younger, Indigenous, and having more criminal charges before treatment entry were associated with an increased risk of criminal offending after starting treatment.

Lead author of the study, Dr Natasa Gisev, a UNSW Scientia Fellow at NDARC, said: “This study adds important new evidence to support the benefits of OAT in reducing crime rates.” Our findings show that OAT is associated with a significant reduction in overall charge rates and is most protective with increased treatment engagement.”

“Importantly, we found that episodes of continuous treatment were associated with lower charge rates compared to those where individuals cycled in and out of treatment. We therefore need to focus on encouraging greater retention in treatment to maximise the long-term health and social benefits of OAT.

“Offending is a complex issue and many individuals will require additional support. Although pharmacological treatment provides many health benefits and reduces criminal offending, other factors that may contribute to offending such as poverty, unemployment and social and environmental circumstances also need to be addressed.” 

Professor Matt Hickman, co-Director of the NIHR Health Protection Research Unit in Evaluation of Interventions at the University of Bristol, UK and co-author of the study, said: “It is widely assumed that OAT reduces drug-related crime, which is one of the reasons why OAT is such a cost-effective intervention. Unfortunately, the evidence-base has been weak but this unique study greatly strengthens our assumptions and policies to increase availability and prolonged OAT treatment.”

In an accompanying commentary, Professors Tim Millar and Roger Webb from the University of Manchester, UK, said: “The study makes a valuable contribution to the literature in showing that, in general terms, OAT is associated with reduced offending risk, but that this relationship is also complex.”

Citation: The effect of entry and retention in opioid agonist treatment on contact with the criminal justice system among opioid-dependent people: a retrospective cohort study. Gisev N, Bharat C, Larney S, Dobbins T, Weatherburn D, Hickman M, Farrell M, Degenhardt L. Lancet Public Health. 2019; 4(7):e334-e342. DOI: 10.1016/S2468-2667(19)30060-X. 

Commentary: Strong evidence indicating the effectiveness of opioid agonist treatment. Millar T, Webb RT. Lancet Public Health. 2019;4(7):e314-e315. DOI: 10.1016/S2468-2667(19)30100-8.

Further information

About the NIHR HPRU in Evaluation of Interventions at the University of Bristol

The Health Protection Research Unit (HPRU) in Evaluation of Interventions, based in Population Health Sciences at the University of Bristol, is part of the National Institute for Health Research (NIHR) and a partnership between University of Bristol and Public Health England (PHE), in collaboration with University College London, Cambridge Medical Research Council (MRC) Biostatistics Unit and University of the West of England. We are a multidisciplinary team undertaking applied research on the development and evaluation of interventions to protect the public’s health. Our aim is to support PHE in delivering its objectives and functions. Our focus is on the PHE priority area of infection. Follow us on Twitter: @HPRU_EI