Switching of opioid agonist treatment modality during imprisonment: a novel marker for increased support need during and following release from prison

Using Canadian correctional administrative data, Farrell MacDonald and colleagues (2021) established a retrospective cohort study to describe during- and post-prison outcomes among people prescribed opioid agonist treatment (OAT). Outcomes were stratified by OAT modality - oral methadone, sublingual buprenorphine/naloxone, or both (OAT switching) - and included a comparison group who reported illicit opioids as their most used drug in the 12 months before imprisonment but chose not to access OAT.

These data are the first to characterize OAT-switching individuals during imprisonment. While the authors found no difference in the average time to return to custody between individuals released on methadone and buprenorphine, those who switched OAT modality returned to prison 57% faster than those prescribed methadone. However, people in the OAT switching group also exhibited a comparatively greater criminal risk profile. They were more likely to be polysubstance users, had a higher severity of substance use in the 12 months prior to arrest, faced longer sentences, demonstrated increased in-prison positive urine toxicology results, and were more likely to have a mental health concern identified by Correctional Service Canada. They were also more likely to receive disciplinary charges and be involved in security and behavioural incidents (Farrell MacDonald et al., 2021).

The study by Farrell MacDonald et al. (2021) identifies OAT-switching during imprisonment as a novel marker for substance use complexity. This is a group who appear to be experiencing more complex patterns of substance use and may benefit from increased support during community reintegration beyond OAT alone. Early identification of those at increased risk of returning to custody could prompt interventions to support successful community re-entry.

Data describing the impact of different directions of OAT switching, the reasons for switching and OAT retention post-release were not available to the authors and gaps remain in understanding why OAT switching may be associated with negative outcomes. While not explored by Farrell MacDonald et al. (2021), we note that previous research has found that retention in OAT post-release is associated with reductions in the risk of recidivism (Larney et al., 2012), alongside reduced risk of post-release opioid related mortality following prison release (Bird et al., 2015; Degenhardt et al., 2014; Green et al., 2018; Groot et al., 2016; Marsden et al., 2017). The increased rate of return to custody among those who switched OAT modality in prison suggests that OAT-switching may also be a marker for increased risk of OAT discontinuation post-release.

Additional insights come from the subgroup of individuals who elected not to initiate OAT during imprisonment. This group had comparable severity of substance use and a more pronounced link between substance use and crime, and yet were less likely to participate in correctional education, employment and other programming. Previous research has identified stigma surrounding OAT and a desire to be drug-free (including OAT), side effects (e.g. constipation) and a general ambivalence about OAT as personal barriers to treatment uptake among people in Australian prisons (Larney et al., 2017). Future research should prioritise identifying and overcoming these types of personal and structural barriers to OAT enrolment during imprisonment.

A significant concern for prison authorities is the impact of OAT diversion, primarily sublingual buprenorphine/naloxone, on prison operations (Grella et al., 2020). OAT diversion was detected among 13% of those prescribed sublingual buprenorphine/naloxone and 11% of those who switched OAT modality (Farrell MacDonald et al., 2021). As OAT coverage is scaled-up in Canadian prisons, and the number of people in prison on buprenorphine/naloxone increases, the absolute number of diversions may also increase, potentially limiting further OAT expansion (Grella et al., 2020; McKenzie et al., 2009). Alternatively, scaled-up OAT programs may reduce demand for diverted or other illicit opioids through increased access to OAT. Diversion may also be reduced through the use of enhanced dosing-supervision protocols and the addition of long-acting injectable buprenorphine (LAIB) as an OAT modality (Dunlop et al., 2021). The primary public health concern regarding use of diverted and illicit opioids in prison is the risk of overdose. While we do not support diversion of OAT, the use of diverted buprenorphine/naloxone in prison carries a significantly lower risk of overdose compared to use of other illicit opioids, which often contain potent synthetic opioids (e.g. fentanyl) (Bucerius & Haggerty, 2019; Carlson et al., 2020; Kaplowitz et al., 2021). Given the well-established benefits of prison-based OAT (Hedrich et al., 2012), potential diversion of OAT should not be considered a barrier to OAT scale-up.

While Farrell MacDonald et al. (2021) note a growing trend of buprenorphine/naloxone prescribing in Canada, and that that Correctional Service Canada lists buprenorphine/naloxone as their front-line OAT modality, they also describe a general preference for methadone among participants. Approximately half of participants who switched OAT modality switched from methadone to buprenorphine/naloxone. While requiring further investigation in relation to OAT prescription in Canadian prisons, potential encouragement from prison-based prescribers to switch to buprenorphine/naloxone may have contributed to reducing patient autonomy and treatment destabilisation. LAIB may also present a challenge to patient preference. LAIB formulations are attractive to prison officials and health care providers in custodial settings, given the reduced burden on health services and reduced risk of diversion (Dunlop et al., 2021). Although there is the potential to expand access to OAT in custodial settings through greater use of LAIB, there is also the potential, counter-intuitively, for reduced treatment access by restricting availability to OAT modalities preferred by authorities. In one correctional jurisdiction, individuals prescribed sublingual buprenorphine/naloxone were transferred en masse to LAIB during the COVID-19 pandemic (Roberts et al., 2021). In the pandemic context, the benefits of reducing face-to-face contact, particularly in custodial settings, are obvious, and LAIB has shown to be associated with strong treatment retention and other psycho-social outcomes (Lintzeris et al., 2021). This example does, however, highlight the potential for wholesale changes to clinical practice that remove patient choice. As access to buprenorphine/naloxone, LAIB and other OAT modalities grow, both in prison and the community, patient preference and the impact of limiting OAT modality choice must be considered, as matching patient preference to treatment has been shown to be associated with improved health outcomes (Friedrichs et al., 2016).

Finally, while nuanced research that seeks to inform OAT programs to maximise their uptake and benefits during and following imprisonment is important, for many people in prison with histories of drug use, imprisonment offers little rehabilitative value. This population is likely better served through decarceration options to better address the underlying causes of their criminogenic behavior. Alternatives to imprisonment can be more successful in reducing recidivism, cheaper than imprisonment, and do not elevate the risk of opioid-overdose on release (Clark et al., 2017; Gan et al., 2021; Mitchell et al., 2012; Wilson et al., 2006). While advocacy efforts for expanded access to OAT in prisons must continue, alternative responses to imprisonment must also be part of the conversation.