Distribution of hepatitis C virus genotypes in Canada: Results from the LCDC Sentinel Health Unit Surveillance System

A public health response to a newly diagnosed case of hepatitis C associated with lapse in Infection Prevention and Control practices in a dental setting in Ontario, Canada

BACKGROUND

Haliburton, Kawartha, Pine Ridge District Health Unit (HKPRDHU) investigated an exposure in an Ontario operatory dental facility related to a newly diagnosed hepatitis C virus (HCV) infection caused by a virus with an uncommon hepatitis C genotype. Lapses in Infection Prevention and Control (IPAC) and a second epidemiologically-linked case (with the same uncommon hepatitis C genotype) were identified, prompting a broader public health response and outbreak investigation.

OBJECTIVES

a) To describe the investigation of a newly diagnosed case of hepatitis C; b) to describe the broader public health response, and c) to address a paucity in the literature related to the risk of disease transmission in dental settings due to IPAC lapses.

METHODS

A collaborative approach with two dental practices, public health partners and regulatory bodies was used. An IPAC inspection was completed to determine and mitigate the risk of blood borne infection transmission within the facilities. Appropriate protocols were followed for the IPAC investigation and public health response.

RESULTS

The investigation identified a risk of potential HCV transmission between two cases linked to the same dental facility. There were no other epi-linked cases of HCV identified. Challenges included a lack of adherence to IPAC standards in one of the dental settings and awareness in the dental community regarding HCV transmission, coordination with regulatory bodies and public health experts and low uptake of laboratory testing by patients.

CONCLUSION

Despite the unique challenges associated with the investigation, HKPRDHU conducted a successful IPAC lapse investigation and public health response. Public health units need to maintain collaborative approaches with regulated health professionals, their regulatory bodies and public health experts.

Can we afford not to screen and treat hepatitis C virus infection in Canada?

BACKGROUND

Screening for hepatitis C virus (HCV) followed by direct-acting antiviral (DAA) treatment in individuals born between 1945 and 1964 has been shown to be both effective and cost-effective, but the question of affordability remains unresolved. We looked at long-term cost and health outcomes of HCV screening for Ontario up to 2030.

METHODS

We used a validated state-transition model to analyze the budget and health impact of HCV screening followed by DAA treatment in individuals born between 1945 and 1964 versus current practice. We used a payer's perspective, discounting costs at an annual rate of 1.5%. Costs, liver-related deaths, and hepatocellular carcinoma (HCC) and decompensated cirrhosis (DC) cases detected were measured over a 14-year period.

RESULTS

By 2030, the cost of implementing a HCV screening program for individuals born between 1945 and 1964 will add an additional $845 million to the Ontario health care budget. Sensitivity analyses showed that DAA costs had the largest effect on the budget, and decreasing DAA costs to $16,000 will lead to a significantly lower budget impact of $331 million. Regarding population health, a screen-and-treat strategy will prevent 1,199 cases of HCC, 1,565 cases of DC, and 1,665 liver-related deaths by 2030.

CONCLUSIONS

Contrasting the budget impact of this HCV screening strategy with other recommended health services and technologies, we conclude that HCV screening should be considered affordable. If Canada is committed to meeting the targets set out by the World Health Organization, then provinces cannot afford to not expand current screening programs.

Cost-effectiveness of daclatasvir plus sofosbuvir-based regimen for treatment of hepatitis C virus genotype 3 infection in Canada

OBJECTIVE

New regimens for the treatment of chronic hepatitis C virus (HCV) genotype 3 have demonstrated substantial improvement in sustained virologic response (SVR) compared with existing therapies, but are considerably more expensive. The objective of this study was to evaluate the cost-effectiveness of two novel all-oral, interferon-free regimens for the treatment of patients with HCV genotype 3: daclatasvir plus sofosbuvir (DCV + SOF) and sofosbuvir plus ribavirin (SOF + RBV), from a Canadian health-system perspective.

METHODS

A decision analytic Markov model was developed to compare the effect of various treatment strategies on the natural history of the disease and their associated costs in treatment-naïve and treatment-experienced patients. Patients were initially distributed across fibrosis stages F0-F4, and may incur disease progression through fibrosis stages and on to end-stage liver disease complications and death; or may achieve SVR. Clinical efficacy, health-related quality-of-life, costs, and transition probabilities were based on published literature. Probabilistic sensitivity analysis was performed to assess parameter uncertainty associated with the analysis.

RESULTS

In treatment-naive patients, the expected quality-adjusted life years (QALYs) for interferon-free regimens were higher for DCV + SOF (12.37) and SOF + RBV (12.48) compared to that of pINF + RBV (11.71) over a lifetime horizon, applying their clinical trial treatment durations. The expected costs were higher for DCV + SOF ($170,371) and SOF + RBV ($194,776) vs pINF + RBV regimen ($90,905). Compared to pINF + RBV, the incremental cost-effectiveness ratios (ICER) were $120,671 and $135,398 per QALYs for DCV + SOF and SOF + RBV, respectively. In treatment-experienced patients, DCV + SOF regimen dominated the SOF + RBV regimen. Probabilistic sensitivity analysis indicated a 100% probability that a DCV + SOF regimen was cost saving in treatment-experienced patients.

CONCLUSION

Daclatasvir plus sofosbuvir is a safe and effective option for the treatment of chronic HCV genotype 3 patients. This regimen could be considered a cost-effective option following a first-line treatment of peg-interferon/ribavirin treatment experienced patients with HCV genotype-3 infection.

A Parallel Sliding Region Algorithm to Make Agent-Based Modeling Possible for a Large-Scale Simulation: Modeling Hepatitis C Epidemics in Canada

Agent-based models (ABMs) are computer simulation models that define interactions among agents and simulate emergent behaviors that arise from the ensemble of local decisions. ABMs have been increasingly used to examine trends in infectious disease epidemiology. However, the main limitation of ABMs is the high computational cost for a large-scale simulation. To improve the computational efficiency for large-scale ABM simulations, we built a parallelizable sliding region algorithm (SRA) for ABM and compared it to a nonparallelizable ABM. We developed a complex agent network and performed two simulations to model hepatitis C epidemics based on the real demographic data from Saskatchewan, Canada. The first simulation used the SRA that processed on each postal code subregion subsequently. The second simulation processed the entire population simultaneously. It was concluded that the parallelizable SRA showed computational time saving with comparable results in a province-wide simulation. Using the same method, SRA can be generalized for performing a country-wide simulation. Thus, this parallel algorithm enables the possibility of using ABM for large-scale simulation with limited computational resources.

Cost-effectiveness of screening for hepatitis C in Canada

BACKGROUND

The seroprevalence of hepatitis C virus (HCV) infection among Canadians is estimated at 0.3% to 0.9%. Of those with chronic HCV infection, 10% to 20% will experience advanced liver disease by 30 years of infection. Targeted screening seems a plausible strategy. We aimed to estimate the health and economic effects of various screening and treatment strategies for chronic HCV infection in Canada.

METHODS

We used a state-transition model to examine the cost-effectiveness of 4 screening strategies: no screening; screen and treat with pegylated interferon plus ribavarin; screen and treat with pegylated interferon and ribavarin-based direct-acting antiviral agents; and screen and treat with interferon-free direct-acting antivirals. We considered Canadian residents in 2 age groups: 25-64 and 45-64 years of age. We obtained model data from the literature. We predicted deaths related to chronic HCV infection, costs, quality-adjusted life-years (QALYs) and incremental cost-effectiveness ratios.

RESULTS

We found that screening and treating would prevent at least 9 HCV-related deaths per 10,000 persons screened over the lifetime of the cohort. Screening was associated with QALY increases of 0.0032 to 0.0095 and cost increases of $124 to $338 per person, which translated to an incremental cost-effectiveness ratio of $34,359 to $44,034 per QALY gained, relative to no screening, depending on age group screened and antiviral therapy received.

INTERPRETATION

A selective one-time HCV screening program for people 25-64 or 45-64 years of age in Canada would likely be cost-effective. Identification of silent cases of chronic HCV infection and the offer of treatment when appropriate could extend the lives of Canadians at reasonable cost.

Distribution of Hepatitis C virus genotypes among newly acquired HCV infections in British Columbia (2000-2013)

BACKGROUND

Characterization of newly acquired Hepatitis C virus (HCV) infections is important in order to understand the epidemiology and spread of HCV.

OBJECTIVE

To describe the Hepatitis C virus (HCV) genotype distribution of newly acquired HCV infections in the province of British Columbia for the period 2000-2013.

METHODS

A descriptive cross-sectional analysis of multi-year data on HCV genotypes. Time trends for the proportion of different HCV genotypes are presented only for newly acquired (incident) HCV infections.

RESULTS

For acute cases, genotype 1a remains the dominant HCV type in circulation (50%), followed by genotype 3a (34%). HCV genotype 1b declined, while genotype 2 was relatively stable. Phylogenetically-related clusters of HCV strains were observed indicating a common source of infection.

CONCLUSION

Enhanced hepatitis surveillance provides a mechanism for monitoring different HCV strains currently circulating in the community. While HCV genotype 1a continues to be the most prevalent, changes in the relative frequency of genotypes 1 and 3 have been observed. This may have important implications for the control and prevention of the infection.

Pretreatment resistance to hepatitis C virus protease inhibitors boceprevir/telaprevir in hepatitis C virus subgenotype 1a-infected patients from Manitoba

BACKGROUND

Traditional therapy with pegylated interferon and ribavirin combined with the new protease inhibitors boceprevir or telaprevir has demonstrated improved outcomes in hepatitis C virus (HCV)-infected patients. Prevalence data regarding pre-existing drug-resistant variants to these two new virus inhibitors in the Canadian population are not available.

OBJECTIVE

To detect pre-existing mutations conferring resistance to boceprevir and⁄or telaprevir in Canadian patients infected with HCV genotype 1a.

METHODS

Resistance-associated mutations (RAMs) were evaluated in 85 patients infected with HCV genotype 1a who had not yet received antiviral therapy. The NS3 protease gene was sequenced and common RAMs were identified based on a recently published list.

RESULTS

The overall prevalence of pre-existing RAMs to boceprevir and telaprevir was higher compared with other similar studies. All of the observed RAMs were associated with a low level of resistance. A surprisingly high proportion of patients had the V55A RAM (10.6%). None of the mutations associated with a high level of resistance were observed. The simultaneous presence of two low-level resistance mutations (V36L and V55A) was observed in only one patient. Three other patients had both T54S RAM and V55I mutations, which may require a higher concentration of the protease drugs. The prevalence of various mutations in Aboriginal Canadian patients was higher (37.5%) compared with Caucasians (16.39%) (P=0.038).

CONCLUSIONS

The present study was the first to investigate pre-existing drug resistance to boceprevir⁄telaprevir in Canadian HCV-infected patients. A relatively high proportion of untreated HCV genotype 1a patients in Manitoba harbour low-level RAMs, especially patients of Aboriginal descent, which may contribute to an increased risk of treatment failure.

Current approaches to HCV infection in current and former injection drug users

Injection drug use (IDU) accounts for 75% of incident cases of hepatitis C virus (HCV) infection in the developed world. Of those infected with HCV, up to 80% will go on to develop chronic disease. Intervention with effective treatment in eligible subjects will limit the impact of the long-term consequences of infection. The use of combination therapy with pegylated interferon and ribavirin may lead to a cure in up to 80% of treated individuals who carry genotype 2 or 3 isolates. Such individuals account for up to 45% of certain cohorts, such as in the inner city of Vancouver. Historically, many IDUs have not received treatment for HCV infection even if it were medically indicated. Recent data (including our own) suggest that, in the right context, response rates similar to those reported in clinical trials of HCV therapy can be achieved in IDUs, even with ongoing drug use. This is all the more important given that prior infection may protect against re-infection even in the presence of ongoing risk behaviors for HCV transmission. The keys to a successful program appear to be appropriate patient selection as well as the delivery of care within an appropriate setting, preferably with a multidisciplinary team in a way that addresses the issue of addiction and other conditions simultaneously. The development of such programs may be quite complex, but the ultimate benefit (for the treated population and for society as a whole) is certainly worth the effort.

Directly observed therapy for the treatment of hepatitis C virus infection in current and former injection drug users

BACKGROUND AND AIM

There are few studies investigating the treatment of hepatitis C virus (HCV) infection in current and former drug users. With this in mind, we sought to evaluate the antiviral efficacy of interferon alpha-2b (IFN alpha-2b) or pegylated-interferon alpha-2b (PEG-IFN alpha-2b) and ribavirin (RBV) in injection drug users (IDU) enrolled in a directly observed therapy (DOT) program, as measured by sustained virologic response (SVR).

METHODS

Viremic HCV-infected IDU, with alanine aminotransferase (ALT) >1.5x upper limit of normal (ULN) were offered 24-48 week (based on HCV genotype) therapy with RBV (800-1200 mg/day, based on weight) along with IFN alpha-2b (3 million IU thrice weekly) replaced by PEG-IFN alpha-2b (1.5 ìg/kg once weekly) as it became available. All injections were directly observed. The primary endpoint was SVR.

RESULTS

Overall, 40 patients (33 males) received IFN alpha-2b (12) or PEG-IFN alpha-2b (28), 55% with HCV genotypes 2 or 3. Only 14 discontinued therapy, 5 due to toxicity, 6 due to illicit drug use and 3 did not achieve an early virologic response. In an intent-to-treat analysis, the overall SVR was 55% (22/40), 64% (14/22) in subjects with genotypes 2/3. There was no significant difference in response rates among those with >6 (50%) or <or=6 months (64%) drug abstinence (P = 0.51) or among those with (53%) and without (57%) intercurrent drug use (P = 0.99); however, frequent users (n = 9) had a decreased SVR (22%) when compared with occasional users (n = 10, 80%, P = 0.12).

CONCLUSION

Treatment of HCV in current and former IDU within a multidisciplinary DOT program can be successfully undertaken, resulting in SVR similar to those in randomized controlled trials.

Rapid genotyping of hepatitis C virus by primer-specific extension analysis

Quick and accurate genotyping of hepatitis C virus (HCV) is becoming increasingly important for clinical management of chronic infection and as an epidemiological marker. Furthermore, the incidence of HCV infection with mixed genotypes has clinical significance that is not addressed by most genotyping methods. We have developed a fluorescence-based genotyping assay called primer-specific extension analysis (PSEA) for the most prevalent HCV genotypes and have demonstrated the capacity of PSEA-HCV for detecting mixed-genotype HCV infections. PSEA-HCV detects genotype-specific sequence differences in the 5' untranslated region of HCV in products amplified by the COBAS AMPLICOR HCV Test, v2.0. Simulated mixed HCV infection of plasma with RNase-resistant RNA controls demonstrates that PSEA-HCV can detect as many as five genotypes in one specimen. Furthermore, in dual-genotype simulations, PSEA-HCV can unequivocally detect both genotypes, with one genotype representing only 3.1% of the mixture (313/10,000 IU in starting plasma). Compared to INNO-LiPA HCV II, both assays determined the same genotype for 191/199 (96%) patient specimens (175 subtype and 16 genotype-only identifications). Following the initial evaluation, PSEA-HCV was used routinely to genotype HCV from patient specimens submitted to our laboratory (n=312). Seventeen (5.4%) mixed infections were identified. The distribution of single-infection HCV genotypes in our population was 60.9% type 1 (n=190), 12.8% type 2 (n=40), 20.2% type 3 (n=63), 0.3% type 4 (n=1), and 0.3% other (n=1). In conclusion, PSEA-HCV provides an inexpensive, high-throughput screening tool for rapid genotyping of HCV while reliably identifying mixed HCV infections.

Injection drug use and the hepatitis C virus: considerations for a targeted treatment approach--the case study of Canada

Infection with the hepatitis C virus (HCV) is a major public health burden in Canada and globally. The literature shows that injection drug use is currently the primary transmission route for HCV, and that a majority of injection drug users (IDUs) are currently infected with HCV in Canada. This article first reviews the burden of HCV within IDU populations and the transmission risks and the treatment implications specific to IDUs. Traditionally, IDUs have been excluded from HCV treatment unless abstaining from illicit drug use. However, recent research suggests that categorical exclusion is not medically necessary. A series of key questions about the feasibility of offering HCV treatment to IDUs in the specific Canadian context are considered, including concerns related to the motivation of treatment for IDUs, treatment delivery, treatment side effects, HCV reinfection, and the social environment. The article concludes that treatment of HCV-infected illicit drug users is both feasible and may be necessary to reduce transmission and adverse outcomes in this high-risk population.