Aims
To estimate and test the difference in rates of violent and non-violent crime during medicated and non-medicated methadone treatment episodes.

Design, Setting and Participants
The study involved linkage of population level administrative data (health and justice) for all individuals (n = 14 530) in British Columbia, Canada with a history of conviction and who filled a methadone prescription between 1 January 1998 and 31 March 2015. Methadone maintenance treatment was the primary independent variable and was treated as a time-varying exposure. Each participant’s follow-up (mean: 8 years) was divided into medicated (methadone was dispensed) and non-medicated (methadone was not dispensed) periods with mean durations of 3.3 and 4.6 years, respectively.

Measurements
Socio-demographics of participants were examined along with the main outcomes of violent and non-violent offences.

Findings
During the first 2 years of treatment (≤ 2.0 years), periods in which methadone was dispensed were associated with a 33% lower rate of violent crime [0.67 adjusted hazard ratio (AHR), 95% confidence intervals (CI) = 0.59, 0.76] and a 35% lower rate of non-violent crime (0.65 AHR, 95% CI = 0.62, 0.69) compared with non-medicated periods. This equates to a risk difference of 3.6 (95% CI = 2.6, 4.4) and 37.2 (95% CI = 33.0, 40.4) fewer violent and non-violent offences per 100 person-years, respectively. Significant but smaller protective effects of dispensed methadone were observed across longer treatment intervals (2.0 to ≤ 5.0 years, 5.0 to ≤ 10.0 years).

Conclusions
Among a cohort of Canadian offenders, rates of violent and non-violent offending were lower during periods when individuals were dispensed methadone compared with periods in which they were not dispensed methadone.

Angela Russolillo, Akm Moniruzzaman, Lawrence C. McCandless, Michelle Patterson, Julian M. Somers
Addiction, 19 November 2017
DOI: 10.1111/add.14059
http://onlinelibrary.wiley.com/doi/10.1111/add.14059/abstract

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