Treatment scale-up among injectable drug users key to HCV elimination in SG

Achieving the World Health Organization’s (WHO) target to eliminate hepatitis C virus (HCV) by 2030 is possible in Singapore, but this requires immediate scaling up of treatment among injectable drug users (IDUs) together with harm reduction efforts, as suggested in a study.

IDUs make up the vast majority of HCV-infected population locally, according to the study authors. But even with the decline in injectable drug use and the introduction of pan-genotypic direct-acting antiviral (DAA) regimens into government subsidy programmes, barriers remain with regard to sufficient testing, linkage to care, and a lack of a national strategy for HCV elimination.

“Without a national directive and committed funding to both testing and treatment, it is unlikely the scale-up of treatment required would be achievable,” they said.

To determine the level and prioritization of intervention needed to achieve the WHO targets of reducing new HCV infections by 80 percent and related deaths by 65 percent by 2030, the authors developed a dynamic model of HCV transmission and disease progression among current and former IDUs in Singapore (about 11,000 with drug use history in 2017, 45 percent HCV seropositive) in a setting with declining injectable drug use but no harm reduction interventions.

The model estimates a total of 3,855 IDUs with chronic HCV infection in 2019, which will decrease to 3,330 in 2030 without any intervention. Projections for new HCV cases followed a similar pattern, with the numbers falling from 148 in 2019 to 113 in 2030. HCV-related deaths remain relatively flat from 62 to 58 during the same period.  [J Gastroenterol Hepatol 2020;doi:10.1111/jgh.15211]

To achieve the target of an 80-percent decrease in HCV incidence, 272 individuals have to be treated in 2019 or a total of 2,444 by 2030. These numbers will decrease with targeted treatment, specifically by about 60 percent if IDUs are prioritized (105 individuals in 2019 or a total of 949 by 2030) or by about 30 percent if IDUs with cirrhosis or more advanced liver disease are prioritized (186 individuals in 2019 or a total of 1,677 by 2030). The target cannot be achieved with prioritization of cirrhotic individuals.

“Harm reduction implementation, such as opiate substitution therapy (OST), could [further] reduce treatments required and provide additional benefits, such as prevention of HIV and overdose,” the authors noted. They pointed out that if scaled-up to 40 percent, OST should reduce treatment requirement by 20.7 percent with random allocation and 23.7 percent with IDU prioritization.

Meanwhile, achieving the 65-percent reduction in mortality target requires more treatment than needed to achieve the incidence target, that is, 631 individuals in 2019 or a total of 3,816 over by 2030.

“Based on a current estimated cost of HCV treatment (including DAAs and delivery) of SGD 9,834, treating 630 patients in 2019 as required by our model to achieve both WHO targets would require SGD 6.2 million, representing 0.05 percent of the total allocated healthcare expenditure budget,” the authors said.

“Concomitant OST would reduce the annual cost by reducing the numbers needed to treat to reach HCV elimination,” they added. “However barriers to scale-up remain in Singapore given problems faced during buprenorphine availability between 2002 and 2006, which some [IDUs] injected for recreational drug purposes instead, thus eventually resulting in its abandonment.” [Singapore Med J 2006;47:919-921]

The authors believe that future OST schemes can be effective if they are to be centralized and administered by the National Addiction Services under strict protocol. They also said that OST expansion may help expand the ability to diagnose HCV among IDUs, highlighting that HCV case-finding is critical to reaching the target.

“[Other] strategies to improve case finding could include universal screening in foci of high HCV prevalence such as the National Addiction Services, Singapore Prison Services, and halfway houses,” they said. “At present, haemodialysis patients are the only group which receive three monthly mandatory universal HCV screening.”

The present analysis is consistent with studies indicating fewer treatments are required if treatment is prioritized to IDUs and individuals with cirrhosis or more advanced disease, as well as if harm reduction is provided in combination, they said. [Int J Epidemiol 2018;47:550-560; Hepatobiliary Pancreat Dis Int 2019;18:143-148]