by Michael Carter
Implementation of comprehensive harm reduction policies has achieved impressive reductions in incidence of hepatitis C virus (HCV) infections among people who inject drugs (PWID) in Scotland, research publish in PLOS ONE shows.
In 2008, the Scottish government expanded access to sterile injecting equipment and also improved the provision of opioid substitution treatment. HCV incidence among people who inject drugs declined sharply between 2008 and 2012 and the investigators estimated that the harm reduction interventions averted 1000 new chronic HCV infections in this population.
“We observed a decline in HCV incidence among PWID during a period of harm reduction services in Scotland,” comment the authors. “This is the first study to demonstrate that impressive reductions in HCV incidence can be achieved among PWID over a relatively short period through high coverage of a combination of interventions.”
Hepatitis C is a blood-borne virus and people who inject drugs are at high risk of contracting the infection through the use of non-sterile injecting equipment.
Harm reduction services for people who inject drugs have tended to focus on the provision of clean needles and syringes and opioid substitution therapy. However, it is known that sharing of other injecting paraphernalia – spoons, filters and water – is associated with hepatitis C transmission.
In 2008, the Scottish government introduced a comprehensive programme of harm reduction interventions to prevent hepatitis C infections among people who inject drugs. The package included the distribution of sterile injecting packs including filters and spoons as well as needles and syringes and also improvements in opioid substitution therapy.
A team of investigators designed a study to examine the impact of these interventions on hepatitis C infection rates among people who inject drugs between 2008 and 2012. They explored changes in access to harm reduction interventions; associations between uptake of interventions and injecting risk behaviour; and the number of new hepatitis C infections averted by the introduction of the interventions and their uptake.
The study population consisted of 8000 people who inject drugs who were recruited to three separate cross-sectional studies. Approximately three-quarters (72 to 73%) were male, mean age was between 34 and 35 and mean time since the onset of injecting was 10.5 to 11.6 years.
There were major changes in service provision after 2008. Between 2008/9 and 2009/10, provision of filters and spoons increased sixfold and fourfold, respectively. Distribution of sterile needles and syringes remained stable, with approximately 4.7 million distributed each year.
The proportion of people who reported currently receiving opioid substitution therapy increased from 50% in 2008/9 to 64% in 2011/12. The proportion of people reporting access to sterile spoons and filters increased from between a fifth and a quarter in 2008/9 to approximately 70% in 2011/12.
There were declines in the proportion of individuals who reported daily injecting (from 63% to 49%), sharing needles/syringes (15% to 8%), reusing one’s own needles/syringes (64% to 45%), sharing spoons (42% to 20%), sharing filters (33% to 17%) and sharing water (31% to 21%). All these reductions were significant.
There were a total of 53 incident HCV infections. The incidence rate declined from 13.6 per 100 person years in 2008/9 to 7.3 per 100 person years in 2011/12.
High needle/syringe and paraphernalia coverage (compared to low coverage) was associated with a reduced risk of recent HCV infection (AOR = 0.14, 95% CI, 0.04-0.48, p = 0.002; AOR = 0.11, 95% CI, 0.03-0.44, p = 0.002).
People with high coverage of needle/syringe/paraphernalia who were also on opioid substitution therapy had a significantly lower risk of recent HCV infection compared to people with the lowest levels of service coverage.
The estimated number of new HCV infections declined from 1063 in 2008 to 566 in 2012. The number of new chronic infections fell from 787 in 2008 to 419 in 2012. The authors estimate that 1400 new infections and 1000 chronic infections were averted by the scale-up of harm reduction between 2008 and 2012.
“These data provide evidence of a downward trend in HCV incidence among PWID in Scotland,” conclude the investigators. “Future monitoring of PWID will be required to establish whether the downward direction in HCV transmission…is sustained.”