December 17, 2015
As mentioned in earlier CATIE News bulletins, the development and licensure of all-oral regimens for the treatment of hepatitis C virus (HCV) infection will usher in a new era of treatment success. These drugs, called direct-acting antivirals (DAAs), are associated with very high rates of cure -- around 95%. Furthermore, these drugs are generally well tolerated and are usually taken for only 12 weeks. As a result, researchers, policy analysts, doctors and other stakeholders are beginning to consider the steps needed to dramatically reduce or even virtually eliminate the HCV epidemic in some high-income countries and regions.
Researchers at the British Columbia Centre for Excellence in HIV/AIDS, together with others at the Kirby Institute (Sydney, Australia), the BC Centre for Disease Control and the University of British Columbia have collaborated on an important project. Their efforts have led to the development of a mathematical model to explore the impact of different options to substantially reduce the HCV epidemic in this province.
The analyses from their model suggest that the widespread use of DAAs , given their potency and tolerability, is likely to help bring about the virtual end of the HCV epidemic. However, such massive change will require the enhanced deployment of low-barrier HCV testing and counselling, followed by swift access to care and treatment in cases of positive results, all on a large scale.
The researchers note that many people who have acquired HCV in B.C. in the recent era did so, in part, because of struggles with addiction and mental health. Therefore, in order to help people who are cured from being re-infected with HCV, programs that address mental health and addiction issues will need to be made available to people who are at high risk for re-infection.
Researchers used data from the year 2012 because it was the most recent year with complete data that could be used for the purposes of developing their model. According to the data, in B.C. there are just over 18,000 people who inject drugs and the research team estimated that about 65% of this group is infected with HCV. Using these data from clinical trials and other figures, the researchers projected the impact of different interventions on the HCV epidemic in that province starting in 2016 through 2030.
The researchers found that a substantial fall in the HCV epidemic would occur if regimens containing only DAAs were used.
They also modelled treatment access using small, medium and large numbers of people to determine the impact on the epidemic. Here are a couple of examples:
Access to HCV treatment in Canada is generally subsidized by provincial and territorial Ministries of Health. As the price of such treatment is high, these bodies ration access to treatment. One common way of rationing treatment is to only allow it in cases where there is some degree of HCV-associated liver injury (scarring, graded as F2 or greater). According to the B.C. researchers, if this policy of limiting access based on liver injury were to continue, "we would never stabilize the [HCV] epidemic and disease elimination would not be possible."
The B.C. team noted that efforts to squash the HCV epidemic cannot only rely on DAA-based treatment regimens alone. They pointed out that "an enhanced harm-reduction program focused on individuals highly vulnerable to re-infection after successfully completing therapy can further decrease the impact of the epidemic."
Evidence cited by the research team suggests that the street drugs commonly injected in B.C. are cocaine and heroin. According to the researchers, "since 2005 the use of methamphetamine has been increasing, but it is still at a lower level than [cocaine and heroin]."
The B.C. researchers said that the success of any plan to dramatically reduce the size of the HCV epidemic will depend on efforts to "identify and [offer testing] to individuals unaware that they are HCV positive. To do so, it is important that different agencies in our healthcare system implement an aggressive 'seek' campaign to identify and [offer testing to these individuals]."
The research team noted that many people who inject street drugs "also suffer from mental illness or other [conditions] and ... there is some reluctance on the part of healthcare providers to engage these individuals into HCV assessment and treatment due to fear of non-adherence." However, the team notes that clinical trials of HCV treatment have found that when people who inject drugs are supported, they do just as well on treatment as those who do not inject drugs. Furthermore, the B.C. researchers said that concerns about "adherence could be addressed by directly observed therapy, consistent with the approach taken to treat opioid dependence in B.C." Even so, they added that an "aggressive seek, test and treat approach would still be necessary as would a retention in care and harm-reduction strategy to minimize the risk of re-infection."
The B.C. team plans to refine its model in the future to include other factors such as modelling the impact of interventions in people who inject street drugs who are co-infected with HCV and HIV.
Their findings suggest that large-scale interventions in that province's HCV epidemic have the potential to reduce the burden of HCV-related illness and death. Their findings also provide strong support for scaling up the response to a serious epidemic. Public health officials, healthcare professionals, policy analysts and community members can now come together to explore different scenarios to cure people, reduce cases of new infections and perhaps virtually eliminate HCV in B.C.
The B.C. mathematical model could serve as a template for other regions that are also considering ways to bring a swift end to the HCV epidemic.
Understanding cirrhosis of the liver: First steps for the newly diagnosed -- Canadian Association of Hepatology Nurses (CAHN), CATIE
Harvoni -- CATIE fact sheet
Holkira Pak -- CATIE fact sheet
Lima VD, Rozada I, Grebely J, et al. Are interferon-free direct-acting antivirals for the treatment of HCV enough to control the epidemic among people who inject drugs? PLoS One. 2015 Dec 3;10(12):e0143836.
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