Determining the impact of opioid substitution therapy upon mortality and recidivism among prisoners: A 22 year data linkage study.

Prisoners experience very high rates of drug dependence, health problems and premature mortality. Without intervention they are highly likely to come into further contact with the criminal justice system, creating further health risk. Opioid dependence is a common problem among prisoners, and opioid substitution therapy (with methadone and buprenorphine) for opioid dependence may be an effective intervention in preventing morbidity, mortality and offending. Using retrospective data linkage, this study evaluated engagement with treatment, patterns of offending, incarceration and mortality among opioid-dependent people who received OST in New South Wales, Australia, at some time between 1985-2010. We linked all OST records with data on all court appearances 1993-2011, custody episodes 2000-2012, and mortality 1985-2012. A total of 638,545 charges were laid against cohort members between 1993-2011. Eight in ten males (79.7%) and 67.9 percent of females had at least one charge; rates were 94.15 per 100 PY (95% CI 93.89-94.41) among males, and 53.19 per 100 PY (95% CI 52.91-53.46) among females, and highest at 15-19 years (175.74 per 100 PY males (95% CI 174.45-177.03), 75.60 per 100 PY females (95% CI 74.46-76.76)) and 20-24 years (144.61 per 100 PY males (95% CI 143.70-145.53), 84.50 per 100 PY females (95% CI 83.53-85.48)). The most frequent charges were theft (24.5% of all charges), traffic/vehicle offences (16.3%), offences against justice procedures (10.5%), illicit drug offences (10.0%), intentional injury offences (9.9%) and public order offences (8.9%). Almost four in ten of the cohort (37%; 43% of men and 24% of women) had at least one episode of incarceration between 2000-2012. Men had a median of 3 (ranging between 1-47) incarcerations, and women, 2 (ranging between 1-35). Costs of incarceration of this cohort between 2000 and 2012 totalled nearly AUD$3 billion. Our findings suggest that a substantial minority of opioid dependent people experience incarceration, usually on multiple occasions and at significant cost. Of the 34,962 people in the cohort, 6,830 were Indigenous and 28,132 were non-Indigenous. Among the 6,830 Indigenous people, 4,615 (67.6%) were male and 2,215 (32.4%) female. The median number of charges against Indigenous people (25, IQR 31) was significantly greater than non-Indigenous people (9, IQR 16) (p<0.001). The median proportion of follow-up time that Indigenous males and females spent in custody was twice that of non-Indigenous males (21.6% vs. 10.1%, p<0.001) and females (6.1% vs. 2.9%, p<0.001). The proportion of Indigenous people who first commenced OST in prison (30.2%) was three times that of non-Indigenous people (11.2%) (p