Effect of Incarceration and Opioid Treatment Transitions on Risk of Hospitalization with Bacterial Infections

"Within a large cohort of people with opioid use disorder in New South Wales, Australia, we performed a self-controlled study to test the effect of incarceration and OAT transitions on the risk of hospitalization with injection drug use-associated bacterial infections. Compared to time between five and 52 weeks continuously living in the community, incidence of injecting-related infections increased before incarceration; was similar during the first two weeks of incarceration; and then substantially decreased among people in prison for more than three weeks. Risk was again elevated in the weeks immediately following release from prison. Compared to time between five and 52 weeks continuously receiving OAT, incidence of injecting-related infections was highest during the weeks both before and after OAT initiation and OAT discontinuation. Overall, we found that risk for injecting-related bacterial infections varies greatly within-individuals over time. Social contextual factors likely contribute to the substantially raised risks around transitions in incarceration and OAT exposure. People entering and leaving prison, and people starting and stopping OAT, may benefit from improved access to harm reduction programs and health and social services to prevent injecting-related bacterial infections. Changes in the risk of hospital admissions with injecting-related infections in and out of prison and OAT may also reflect changes in the ability to access primary and secondary health services.

"The increase in risk immediately following prison release may reflect return to injection use, poor access to health and social supports, and material deprivation (poverty and homelessness) (Binswanger et al., 2012; Joudrey et al., 2019; Treloar et al., 2021). This underscores that people leaving prison would benefit from better health, social, and economic supports, and linkages to harm reduction services and primary care. The excess risk for injecting-related infections during this time period (when compared to people injecting drugs in the community at other times, we estimate 1.45 times the risk, 95% CI 1.22-1.72) may be more modest than that seen for overdose (e.g., 2.44 times higher fatal overdose rate in a cohort study from New South Wales, Australia (Degenhardt et al., 2014); 2.76 times higher nonfatal overdose risk in a self-controlled cases series from British Columbia, Canada (Keen et al., 2021)). Incarceration often leads to loss of opioid tolerance, especially among people not receiving OAT in prison (Degenhardt et al., 2014; Joudrey et al., 2019), which likely increases overdose risk more so than infection risk. Given that the median duration of prison stay was only 16 days, excess risk of infection-related hospitalization after release may also reflect people seeking treatment outside prison for infections that initially developed before or during incarceration (Lloyd et al., 2015)."