Does exposure to opioid substitution treatment in prison reduce the risk of death after release? A national prospective observational study in England.
OBJECTIVE
People with opioid use disorder (OUD) in prison face an acute risk of death after release. We estimated whether prison-based opioid substitution treatment (OST) reduces this risk.


METHODS
Prospective observational cohort study using prison health care, national community drug misuse treatment and deaths registers.


METHODS
Recruitment at 39 adult prisons in England (32 male; seven female) accounting for 95% of OST treatment in England during study planning.


METHODS
Adult prisoners diagnosed with OUD (recruited: September 2010-August 2013; first release: September 2010; last release: October 2014; follow-up to February 2016; n = 15 141 in the risk set).
At release, participants were classified as OST exposed (n = 8645) or OST unexposed (n = 6496). The OST unexposed group did not receive OST, or had been withdrawn, or had a low dose.


METHODS
Primary outcome: all-cause mortality (ACM) in the first 4 weeks.


RESULTS
drug-related poisoning (DRP) deaths in the first 4 weeks; ACM and DRP mortality after 4 weeks to 1 year; admission to community drug misuse treatment in the first 4 weeks. Unadjusted and adjusted Cox regression models (covariates: sex, age, drug injecting, problem alcohol use, use of benzodiazepines, cocaine, prison transfer and admission to community treatment), tested difference in mortality rates and community treatment uptake.


RESULTS
During the first 4 weeks after prison release there were 24 ACM deaths: six in the OST exposed group and 18 in the OST unexposed group [mortality rate 0.93 per 100 person-years (py) versus 3.67 per 100 py; hazard ratio (HR) = 0.25; 95% confidence interval (CI) = 0.10-0.64]. There were 18 DRP deaths: OST exposed group mortality rate 0.47 per 100 py versus 3.06 per 100 py in the OST unexposed group (HR = 0.15; 95% CI = 0.04-0.53). There was no group difference in mortality risk after the first month. The OST exposed group was more likely to enter drug misuse treatment in the first month post-release (odds ratio 2.47, 95% CI = 2.31-2.65). The OST mortality protective effect on ACM and DRP mortality risk was not attenuated by demographic, overdose risk factors, prison transfer or community treatment (fully adjusted HR = 0.25; 95% CI = 0.09-0.64 and HR = 0.15; 95% CI = 0.04-0.52, respectively).


CONCLUSIONS
In an English national study, prison-based opioid substitution therapy was associated with a 75% reduction in all-cause mortality and an 85% reduction in fatal drug-related poisoning in the first month after release.
Addictions Department, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
John
http://orcid.org/0000-0002-1307-2498
J
Marsden
Addictions Department, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
Garry
G
Stillwell
School of Social and Community Medicine, Faculty of Health Sciences, University of Bristol, Bristol, UK.
Hayley
H
Jones
Alcohol, Drug and Tobacco Division, Health and Wellbeing Directorate, Public Health England, London, UK.
Alisha
A
Cooper
Alcohol, Drug and Tobacco Division, Health and Wellbeing Directorate, Public Health England, London, UK.
Brian
B
Eastwood
National Drug and Alcohol Research Centre, University of New South Wales, New South Wales, Australia.
Michael
M
Farrell
Alcohol, Drug and Tobacco Division, Health and Wellbeing Directorate, Public Health England, London, UK.
Tim
T
Lowden
Alcohol, Drug and Tobacco Division, Health and Wellbeing Directorate, Public Health England, London, UK.
Nino
N
Maddalena
School of Social and Community Medicine, Faculty of Health Sciences, University of Bristol, Bristol, UK.
Chris
C
Metcalfe
Institute of Brain, Behaviour and Mental Health, University of Manchester, Manchester, UK.
Jenny
J
Shaw
School of Social and Community Medicine, Faculty of Health Sciences, University of Bristol, Bristol, UK.
Matthew
M
Hickman
D000328:Adult; D015331:Cohort Studies; D062787:Drug Overdose / Q000517:prevention & control*; D004739:England; D005260:Female; D006801:Humans; D008297:Male; D058850:Opiate Substitution Treatment / Q000706:statistics & numerical data*; D009293:Opioid-Related Disorders / Q000628:therapy*; D011329:Prisoners / Q000706:statistics & numerical data*; D011330:Prisons; D011446:Prospective Studies; D012307:Risk Factors; D040242:Risk Reduction Behavior
All-cause mortality; drug-related poisoning mortality; heroin; opioid substitution treatment; opioid-use disorder; prison