Theme: Epidemiology & Public Health Research Year: 2018
Background:
Needle-syringe programs (NSP) and opioid agonist therapy (OAT) form the basis of
harm reduction among PWID. While OAT is consistently associated with reduced
risk of HCV acquisition, the impact of NSP remains unclear, and most of the
evidence for their combined effect relies on modelling projections. Though important
to inform elimination strategies, no studies have examined whether NSP/OAT have
similar effects among HCV-naïve and previously-infected PWID.
Aims:
1. Estimate the rate of HCV infection and its association with NSP/OAT coverage
among PWID in Montreal;
2. Compare estimates among HCV-naïve and previously-infected PWID.
Methods:
Design: prospective cohort (2010-2017). Eligible participants reported past-6-month
injection at enrolment, previous opioid/OAT use, and tested HCV-Ab-negative or
Ab+/RNA-negative. NSP/OAT data was collected and HCV testing performed at 3/6-
month visits to detect primary or recurrent HCV (Ab+ or RNA+ test among previously
negative participants, respectively). OAT coverage was defined by self-reported
current dose: high (≥60mg/day); low (<60mg/day); none. High NSP coverage was
defined as reporting 100% safe needle-syringe sources in the past 3/6m (vs <100%).
Combined coverage was defined as: minimal=low both OAT/NSP; full=high both
OAT/NSP; partial=other OAT/NSP combinations. Cox regression models estimated
associations between harm reduction coverage and time-to-HCV-infection.
Results:
56 primary and 50 recurrent HCV events were observed over 526 and 657
respective person-years of follow-up: IRP=10.6/100py; IRR=7.6/100py. Full coverage
of harm reduction was associated with a 70% and 60% reduced risk of HCV
acquisition (vs. partial and minimal, respectively). High-dose OAT was associated
with a 65% and 75% reduction in HCV infection risk, vs. low-dose-OAT and no OAT,
respectively. NSP alone was not significantly associated with HCV incidence.
Estimates were similar among HCV-naïve and previously-infected PWID.
Conclusion:
Full coverage of harm reduction interventions, particularly high-dose OAT, should be
promulgated alongside treatment-as-prevention approaches to reduce ongoing HCV
transmission among both HCV-naïve and previously-infected PWID.
Disclosure of Interest Statement:
NM and AAA are supported through CanHepC PhD trainee scholarships. JB is
receiving advisor fees from Gilead Sciences and Merck and a research grant from
Gilead Sciences, outside of this current work. None of the other authors have
commercial relationships that may pose a conflict of interest in connection with this
work.