Is use of opioid agonist treatment associated with broader primary healthcare use among men with recent injecting drug use histories following release from prison? A prospective cohort study

BACKGROUND: A precipitous decline in health status among people recently released from prison is common. In Victoria, Australia, opioid agonist treatment (OAT) in the community involves frequent contact with primary care, potentially facilitating broader use of primary healthcare services. Among a cohort of men who injected drugs regularly pre-imprisonment, we estimated differences in rates of primary healthcare use and medication dispensation between people who did and did not receive OAT post-release. METHODS: Data came from the Prison and Transition Health Cohort Study. Three-month post-release follow-up interviews were linked with primary care and medication dispensation records. Generalised linear models were fit with one exposure (OAT: none/partial/complete) for 13 outcomes relating to primary healthcare use, pathology testing, and medication dispensation, adjusted for other covariates. Coefficients were reported as adjusted incidence rate ratios (AIRR). RESULTS: Analyses included 255 participants. Compared to no OAT use, both partial and complete OAT use were associated with increased rates of standard (AIRR: 3.02, 95%CI: 1.88–4.86; AIRR: 3.66, 95%CI: 2.57–5.23), extended (AIRR: 2.56, 95%CI: 1.41–4.67; AIRR: 2.55, 95%CI: 1.60–4.07) and mental health-related (AIRR: 2.71, 95%CI: 1.42–5.20; AIRR: 2.27, 95%CI: 1.33–3.87) general practitioner (GP) consultations, total medication (AIRR: 1.88, 95%CI: 1.19–2.98; AIRR: 2.40, 95%CI: 1.71–3.37), benzodiazepine (AIRR: 4.99, 95%CI: 2.81–8.85; AIRR: 8.30, 95%CI: 5.28–13.04) and gabapentinoid (AIRR: 6.78, 95%CI: 3.34–13.77; AIRR: 4.34, 95%CI: 2.37–7.94) dispensations, respectively. Partial OAT use was also associated with increased after-hours GP consultations (AIRR: 4.61, 95%CI: 2.24–9.48) and complete OAT use? with increased pathology utilisation (e.g. haematological, chemical, microbiological or immunological tissue/sample testing; AIRR: 2.30, 95%CI: 1.52–3.48). CONCLUSION: We observed higher rates of primary healthcare use and medication dispensation among people who reported partial and complete OAT use post-release. Findings suggest that access to OAT post-release may have a collateral benefit in supporting broader health service utilisation, underscoring the importance of retention in OAT after release from prison.