Almost half of all ex-prisoner deaths identified through the NCIS were classified as accidental drug-related deaths. Ex-prisoners who died of accidental drug-related causes were on average younger and less likely to be Indigenous, born in Australia, married, or living alone at or around the time of death, compared with those who died from all other reportable causes. Evidence of mental illness or self-harm was less common among accidental drug-related deaths, whereas evidence of previous drug overdose, injecting drug use, history of heroin use and history of drug withdrawal in the previous six months were more common. Consistent with previous research, accidental drug-related deaths in this study were less likely to be associated with psychiatric morbidity or self harm behaviour [
16] and more likely to be associated with being single, poly-drug use, history of heroin dependence, overdose and injecting drug use [
16,
23].
These findings highlight the need to consider drug overdose within the wider context of ex-prisoner experiences so that preventive programmes can be appropriately structured and targeted. For example, in this study the majority of accidental drug-related deaths occurred in a home environment. A previous study in New South Wales also found that the majority of drug-related deaths occurred in a home environment; however, an ambulance was called while the subject was alive in only 10% of cases, and a substantial minority of drug users died alone [
22]. One way to reduce drug-related mortality in ex-prisoners may therefore be to train and support peers and family members to recognise, intervene and seek medical assistance in response to an overdose [
16,
27], possibly in addition to the delivery of take-home naloxone [
28-
30]. Another effective strategy may be to facilitate access to a safer injecting facility (SIF) for those who return to injecting drug use [
31]. This may be achieved by extending the hours of operation for currently operating SIFs, or by funding the operation of more centres. Currently, there is only one SIF operating in Australia, in Kings Cross, Sydney; evaluations have suggested that this SIF has resulted in a reduction in overdose deaths and provided a gateway to drug treatment and counselling [
32].
While the majority of accidental drug-related deaths occurred in a home environment, a significant proportion occurred in a public location such as a car park, railway station or the street (16%). A further 9% occurred in temporary accommodation such as boarding houses or hostels. These findings are consistent with a body of research suggesting a link between accidental overdose and use of drugs in unusual settings [
33,
34]. They may also be understood in terms of the difficulties that many ex-prisoners experience in securing accommodation upon release from custody [
35]. These observations provide insight into potential target areas for transitional programmes for prisoners, such as assistance in securing stable and affordable accommodation post-release [
15].
In the current study, toxicological findings revealed that the majority of accidental drug-related deaths involved a combination of drugs including opioids, benzodiazepines and alcohol. This is consistent with previous research indicating that a significant proportion of drug-related deaths in ex-prisoners involve concurrent use of multiple psychoactive substances, particularly multiple central nervous system (CNS) depressants [
6,
27,
36]. It is now well recognised that concomitant use of opioids with other CNS depressants, such as benzodiazepines and alcohol, increases the risk of overdose [
10]. Indeed, Gossop et al found that for every supplementary drug administered in conjunction with an opioid, the risk of death from opioids nearly doubles [
37]. While there has been much focus on reduced tolerance as a driver of drug overdose in ex-prisoners [
38,
39], these findings indicate that poly-drug use is also important and should be incorporated into multi-faceted interventions. Ex-prisoners may under-estimate the risks posed by decreased tolerance in combination with concomitant use of multiple psychoactive substances. To the extent that this is the case, it may be possible to reduce drug-related deaths in ex-prisoners through educational programs delivered both prior to and after release from custody.
This study had three main limitations. First, data were extracted from largely free-text documents within coronial records and consequently, the information abstracted varied between records, reducing the number of valid observations for particular analyses. Second, it was rarely possible to determine from coronial records when the deceased was released from custody, and thus the amount of time lapsed between release and death. However, recent evidence suggests that ex-prisoner deaths identified through a search of the NCIS are disproportionately drug-related, and occur in the weeks immediately following release [
40]. Further, the aim of this paper was to explore the circumstances surrounding drug-related deaths in ex-prisoners, rather than to add to the already substantial body of evidence [
1,
2,
6,
27] regarding the time between release and death. As we cannot confirm the amount of time lapsed between release from custody and death, the term ‘ex-prisoner’ in the context of this paper, while literally correct, does not necessarily imply recent release, although it does imply prior imprisonment. Third, our search method would have identified only a small proportion of all ex-prisoner deaths [
40], and our conservative decision rule for deeming a death to be of an ex-prisoner may have excluded additional cases from our analysis. Although the sample for this study was therefore a convenience sample, and represented only a small subset of ex-prisoner deaths in Australia, this is the first study to examine drug-related deaths among ex-prisoners nationally, using coronial records.