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Injection drug use harm reduction decreases HCV prevalence

Model projections of scaled-up opioid substitution therapy and needle and syringe programs in Europe demonstrated a potential reduction in hepatitis C prevalence of 18% to 79% and could reduce treatment scale-up need by 20% to 80%.

“Preventing HCV transmission among people who inject drugs (PWID) is critical for averting future liver disease in Europe and elsewhere and new HCV infections in this group,” Hannah Fraser, PhD, from the University of Bristol, United Kingdom, and colleagues wrote. “Primary prevention through opioid substitution therapy (OST) and high-coverage needle and syringe programs (NSPs) can reduce HCV transmission among PWID and averts new HCV infections, but substantial reductions in HCV prevalence are unlikely to be achieved without scaling-up HCV treatment.”

Treatment scaled up, prevalence reduced

Fraser and colleagues developed a stratifying model to estimate the current HCV treatment rates and coverage OST and NSPs among PWIDs in Europe.

The study included 11 sites: Amsterdam, Belgium, Czech Republic, Denmark, Finland, France, Hamburg, Norway, Scotland, Slovenia and Sweden.

The percentage of injection drug users treated for chronic HCV in 2015 and 2016 varied from less than 0.1% in Finland; to a range of 0.5% to 2% in Sweden, Denmark, Belgium, Norway and Amsterdam; to more than 5% in Czech Republic and Slovenia.

At baseline in 2016, the researchers projected that chronic HCV prevalence among PWIDs varied from 20.9% (95% CI, 18.2-23.8) in Czech Republic and 16.2% (95% CI, 10.7-21.7) in Slovenia to 56.1% (95% CI, 53.1-59.4) in Finland and 60% (95% CI, 57.4-62.9) in Sweden.

If all 11 sites switched from interferon therapy to DAAs with the current treatments rates and increased OST and NSP coverage to 80%, the researchers project that HCV prevalence would decrease by 17.6% (95% CI, 10-27.9) in Finland; 19.5% (95% CI, 11.7-27.6) in Hamburg; between 30% and 50% in Scotland, Sweden, France, Norway, Denmark and Belgium; more than 50% in Czech Republic and Amsterdam; and more than 75% in Slovenia.

If the sites were to double their DAA treatment rates and increase OST and NSP coverage by 80%, the projected decrease in HCV prevalence ranged from 17.9% (95% CI, 10.3-28.2) in Finland to 99.5% (95% CI, 91.8-99.9) in Slovenia.

Significant decrease in HCV prevalence in sites with established high baseline treatment rates, such as Czech Republic and Slovenia, was primarily related to doubling DAA treatment rates, with or without scaled-up OST and NSP coverage. In contrast, sites with low baseline treatment rates, such as Finland and Sweden, had more significant reductions in prevalence due to increased OST and NSP coverage rather than doubled DAA treatment rates.

The researchers found that HCV incidence was likely to remain largely unchanged with current OST and NSP coverage in all but three sites if current DAA treatment rates were maintained. However, if OST and NSP coverage was scaled-up by 80%, the projections displayed an approximate decrease of more than 35% at all sites.

The researchers note that among the limitations in their study, data collection was relatively inconsistent across all sites, particularly due to the difficulty in obtaining accurate injection drug user population estimates.

“Robust HCV surveillance data among PWID were not always available and chronic HCV prevalence was uncertain,” the researchers wrote. “To ensure that empirical evidence of the impact of HCV treatment as prevention can be generated, it is important that more attention is given to establishing robust surveillance systems to reduce the uncertainty surrounding chronic HCV prevalence among PWID. The potential and relative costs of introducing effective HCV surveillance are trivial compared to the costs of HCV treatment, and need to be encouraged across Europe.”

‘Lessons should be learnt’

In a related editorial, Margaret Hellard, PhD, FRACP, and colleagues discussed the barriers related to the suggested DAA and harm reduction coverage increases.

“A comprehensive elimination program requires more than just DAAs, and depending on the starting point it can take many years to set up sufficient service diversity, infrastructure capacity and surveillance systems to facilitate the increases in testing and retention in care that are required,” Hellard and colleagues wrote. “Lessons should be learnt from other settings on the most effective models of care to maximize treatment uptake.”

The first barrier discussed is that widespread treatment scale-up is currently precluded by restricted and inconsistent access policies in many European countries, as the model’s projections show the greatest benefit when prevention and treatment scale-up occurred in unison. The second barrier comes in the form of countries’ capacities and health infrastructures to deliver prevention and treatment at the suggested scales. Thirdly, effectively engaging injection drug users will continue to present difficulties in the face of stigma and discrimination built from decades of conservative drug policies.

“The establishment of flexible and culturally acceptable models of care for patients, in particular PWID, has been shown to improve both capacity and engagement. The simplicity of treatments means they can be administered in primary health care settings, rather than confined, as in the era of pegylated interferon and ribavirin, to hospital settings,” Hellard and colleagues wrote. “Universal access to DAAs is required to achieve the WHO 2030 elimination targets and ultimately this will happen in the region. However, while waiting for this to occur, countries should act now to improve their health services infrastructure and ensure the platforms required are in place to successfully deliver scaled-up DAA treatment in a timely manner when universal access does arrive.” – by Talitha Bennett

Disclosure: Fraser reports she received an honorarium from Merck Sharp & Dohme. Please see the full study for the other authors’ relevant financial disclosures.