Initiation, cessation and resumption of attendance at the Melbourne supervised injecting room among a cohort of people who inject drugs

Background:
Supervised injecting facilities (SIFs) reduce drug-related harms and associated costs, but evidence is limited to a few settings. This study estimates rates of initiation, cessation, and resumption of Melbourne’s Medically Supervised Injecting Room (MSIR) use among a cohort of people who inject drugs.

Methods:
Data were drawn from SuperMIX, an ongoing cohort study since 2008. Participants complete baseline and annual surveys, including MSIR use since its opening on 30 June 2018. We reported baseline characteristics and calculated incidence rates (IRs) of MSIR initiation, cessation, and resumption, stratified by recent homelessness and opiate agonist therapy (OAT) use, per 1000 person-years (PY).

Results:
Of 1650 eligible participants, 685 (42%) reported MSIR use at baseline. MSIR attenders were slightly older (median 43 vs. 41 years) and less often female (28% vs. 35%) than non-attenders. Most (71%) were infrequent attenders (<50% injections at MSIR). Frequent attenders (n = 202) injected more often (median monthly injections = 50) than infrequent (median = 30) and non-attenders (median = 20). The MSIR initiation rate was 525 per 1000 PY, similar between frequent and infrequent attenders (RR 1.10, 95% CI 0.94–1.28). The cessation rate was 264 per 1000 PY, with no difference between attendance groups (RR 1.11, 95% CI 0.60–2.04). The resumption rate was 250 per 1000 PY, also similar across infrequent and frequent attenders (RR 0.99, 95% CI 0.47–2.09).

Conclusions:
We found high MSIR service uptake, relative to cessation. Attendance was higher among men, Aboriginal and/or Torres Strait Islander people, and those recently homeless, with frequent attenders injecting more often and those on OAT less likely to attend frequently.