Elimination of hepatitis C among people who inject drugs in Europe will require simultaneous scale-up of direct-acting antiviral treatment, needle and syringe programmes (NSP) and opioid substitution treatment (OST), and a re-think of attitudes to drug policy and harm reduction in Central Europe, according to a modelling study led by researchers from the University of Bristol.
The study findings, published in advance online by the Journal of Hepatology, show that although increasing the number of people treated for hepatitis C may result in large reductions in prevalence in countries with low hepatitis C virus (HCV) prevalence, it will have little impact on new infections in most settings.
Elimination of hepatitis C – which the World Health Organization defines as a 65% reduction in HCV-related deaths and a 90% reduction in new infections by 2030 – will depend on both treatment of existing chronic infections and the prevention of new infections.
Some experts see the potential to eliminate hepatitis C transmission in some populations by diagnosing and treating everyone with hepatitis C but this would depend on treatment being affordable and accessible for all. Rapid elimination through treatment alone also depends on the screening of the population to identify people with hepatitis C and good engagement in health care.
In the European Union, 3.6 million people were estimated to have chronic HCV infection in 2016. Estimates of the number of people with hepatitis C who inject drugs are difficult to arrive at, due to lack of surveillance systems, lack of information about possible sources of exposure and uncertainty about the size of the current injecting population in European countries.
The European Monitoring Centre for Drugs and Drug Addiction estimates that the United Kingdom has the largest number of current injectors in the European Union – over 120,000 – compared with 9900 current injectors in Spain.
Researchers at the University of Bristol and colleagues at other European Union universities developed a model to assess the impact of varying levels of treatment coverage, OST and clean needle and syringe provision on HCV prevalence and incidence up to 2026. They wanted to understand the relative contributions of treatment and prevention to HCV incidence and to determine what levels of treatment and prevention coverage might be necessary in different settings in order to deliver substantial reductions in HCV incidence.
The model used prevalence and population data for eleven cities or countries, reported between 2009 and 2014. The prevalence of HCV among people who inject drugs ranged from 27% in Slovenia to 66% in France, 67% in Scotland and 76% in Finland. The size of the drug-injecting population also varied, from around 6000 people in Slovenia to 80,000 in France. The model did not include all European countries because the object was to compare settings, with different characteristics, rather than arrive at a single estimate for the European Union.
The model compared enhanced rates of treatment and prevention coverage compared to the status quo. It showed that in eight of the eleven sites included in the model HCV prevalence would fall by less than 5% over a decade among people who inject drugs at current rates of treatment uptake. Only in Amsterdam, the Czech Republic and Slovenia would current rates of treatment lead to greater decreases in HCV prevalence.
Even if treatment coverage doubled, this would not be sufficient to reduce prevalence in countries with the highest prevalence, such as Sweden and Finland. In countries with moderate HCV prevalence, such as Scotland, doubling treatment coverage would result in reductions in prevalence of between 11.6% and 23.5%. To achieve substantial reductions in prevalence it would be necessary to treat at least 5% of the drug-injecting population each year. This scale of treatment would achieve a 99% reduction in prevalence in the Czech Republic and Slovenia, but a large reduction in prevalence would only come about in other countries if the coverage of OST and NSP reached 80%.
Achieving HCV incidence below 2% would require treatment coverage to be increased 17 times in Sweden and 200 times in Finland above current levels without scaling up OST and NSP. Even with the scale-up of OST and NSP, treatment coverage would need to expand tenfold in Sweden and 159 times above current levels to force HCV incidence below 2%.
“Reducing HCV incidence to <2% by 2026 requires little action in Amsterdam, Czech Republic and Slovenia, whereas in Belgium, Denmark, Hamburg, Norway, and Scotland it will require at least a fivefold increase in the current HCV treatment rates, or 1.8 to 4.7-fold if OST and NSP are scaled up,” the authors conclude.
They also point out that better surveillance of prevalence and new infections will be needed to achieve elimination, pointing out that the costs of surveillance are trivial in comparison to drug costs but necessary for HCV 'treatment as prevention' to be validated as effective.
"Their findings reiterate the importance of high prevention coverage as a primary method of reducing incidence and prevalence," write Margaret Hellard and colleagues from Monash University, Melbourne, in an accompanying editorial. They draw attention to the need to engage people who inject drugs in harm reduction services and health care, as well as the development of models of care that are acceptable to people who inject drugs, as essential for high uptake of treatment.
Fraser H et al. Model projections on the impact of HCV treatment in the prevention of HCV transmission among people who inject drugs in Europe. Journal of Hepatology, advance online publication (2018), https://doi.org/10.1016/j.jhep.2017.10.010