Providing prison leavers with OST on their final day in custody was associated with a 50 per cent reduced risk of all-cause mortality and a 54 per cent reduced risk of a drug-related death in the four weeks following release, according to analysis by OHID and the Ministry of Justice (MoJ).
Overdose rates are notoriously high in the period immediately after release, largely the result of reduced tolerance.
The report looked at the outcomes for prison leavers in substance misuse treatment in England between 2018 and 2022, analysing more than 270,000 prison spells and linking data from the MoJ’s Prison National Offender Management Information System (p-NOMIS), the ONS mortality register and NDTMS statistics.
Almost 40 per cent of prison spells completed between August 2018 and December 2022 were matched to a prison-based substance misuse record, with spells of between eight and fourteen days more than twice as likely to matched to treatment record than spells of seven days or under. Prison spells for theft had the highest rate of treatment, at more than 60 per cent.
Drug use rates are particularly high for prisoners serving short sentences, with a 2025 MoJ report finding that three quarters of those serving a year or less had an identified substance misuse need. According to NDTMS figures, nearly half of prisoners receiving treatment said opiates were one of their problem substances, while Dame Carol Black’s Independent review of drugs stated that ‘people with serious drug addiction’ now occupy one in three prison places.
There were almost 2,900 deaths linked to prison spells in the analysis data set, 293 of which occurred within four weeks of leaving prison – of these, more than 60 per cent were drug-related deaths. ‘The first week after release had the highest risk of death, with 48.5 per cent of all deaths in the first four weeks after release occurring in the first seven days,’ says the report.
‘This study found that people receiving OST on their final day in prison were significantly less likely to die from drug-related causes within four weeks of release,’ the report concludes. ‘This finding supports previous research and emphasises the effectiveness of OST as a harm reduction strategy, and its potential to save lives during the critical period immediately after release from prison.’
According to a National Audit Office (NAO) report from earlier this year, the prison service had been too slow in responding to the ‘substantial, increasing and rapidly changing’ threat from drugs in the prison estate, including the increasing problem of synthetic drugs. Security weaknesses – such as around the use of drones to smuggle drugs into prisons – needed to be ‘addressed with more urgency’, it stressed, with the age and condition of many prisons making them particularly vulnerable to smuggling.
A report from HM Inspectorate of Prisons last year concluded that drugs were now undermining ‘every aspect’ of prison life, with rising levels of assaults and a negative impact on rehabilitative work. Former justice secretary David Gauke’s sentencing review, meanwhile, concluded that capacity pressures had brought the prison system ‘dangerously close to collapse’.
Prison leavers in substance misuse treatment: 4-week outcomes is available here