Engagement with the HCV care cascade among high-risk groups: a population-based study

Abstract

Background: Hepatitis C virus (HCV) elimination requires a thorough understanding of the care cascade. A direct-acting-antiviral (DAA)-era description of the care cascade has not been undertaken in Ontario, Canada. Our primary objective was to describe the current population-level care cascade in the general Ontario population and among key risk-groups ─ baby-boomers, immigrants, and individuals experiencing residential instability. The secondary objective was to identify predictors of engagement. Methods: We conducted a population-based cohort study of Ontario residents undergoing HCV testing between January 1, 1999, and December 31, 2018, and mapped the care cascade [antibody diagnosed, RNA tested, RNA positive, genotyped, treated, achieved sustained virologic response (SVR), reinfected/relapsed] as of December 31, 2018. The cascade was stratified by risk groups. Cause-specific hazard modeling was used to identify demographic, and socioeconomic predictors of engagement with key steps of the cascade. Results: Among 108,428 Ontario residents living with an HCV antibody diagnosis, 88% received confirmatory RNA testing; of these, 62% tested positive and 94% of positive tests were genotyped. Of those with confirmed viremia, 53% initiated treatment, and 76% of treated individuals achieved SVR, while ~1% experienced reinfection or relapse. Males, older birth cohorts, long-term residents, those with a history of substance use disorder and social marginalization (e.g., material deprivation, residential instability), and those initially diagnosed in the pre-DAA era exhibited lower rates of engagement with almost every step of HCV care. Conclusions: Despite DAA-era improvements, treatment initiation remains a major gap. HCV screening and linkage-to-treatment, particularly for those with a history of substance use disorder and social marginalization, will be needed to equitably close gaps in HCV care in Ontario.

In search of a ‘good number’: knowledge controversy and population estimates in the endgame of hepatitis C elimination

“…Spontaneous viral clearance is where a positive HCV antibody indicating a history of infection is followed by a negative HCV PCR indicating the absence of virus without treatment. A rate of 9% duplication in notifications across states and territories was assumed since 2019, and since 2022, the rate of spontaneous viral clearance has increased to 36% (from a previously assumed 25%), partly based on estimates elsewhere38–40:…”

“…For instance, in contrast to the accounts of some scientists, the accounts of some community stakeholders emphasised: ‘This isn’t a usual ticking over of the numbers, this is a major, this is a major change that’s proposed’ (P28). The controversy situates altered estimation as a site of ‘scale politics’, producing ‘scalar narratives’40 in the sizing and shaping of hepatitis C as a matter of policy and community concern. Scalar narratives are those that use scale as a resource to explain events and present an argument,41 42 here about hepatitis C. Here is one perspective on this deliberation:…”

Feasibility of hepatitis C elimination by screening and treatment alone in high-income countries

“…First, the model-simulated reported incidence of CHC is very similar to the historical reported incidence in Ontario from 2006 to 2019 (Supplemental Figure S3.1A, http://links.lww.com/HEP/I258). 39 Similarly, the model-simulated CHC-related incidence of DC and HCC (Supplemental Figure S3.1B, http://links.lww.com/HEP/I258 and Supplemental Figure S3.1C, http://links.lww.com/HEP/I258) closely matches the health administrative data records 39 . Lastly, the projected population size, including the high-risk groups simulated by the model, also closely matches the size of Ontario’s population observed from 2006 to 2022 (Supplemental Figure S3.1D, http://links.lww.com/HEP/I258).…”

“…All probabilities regarding disease progression and the efficacy of DAA treatments were collected from the WHO publications and the published literature 1,31–37 . Parameters associated with screening and treatment rates were obtained from published literature based on health administrative data in Ontario 38,39 (Supplemental Table S1.2, http://links.lww.com/HEP/I258). The negative impact on screening and treatment rates due to the COVID-19 pandemic was estimated based on provincial public health data and data from the Canadian Institute for Health Information 8,19 .…”

“…Many parameter values required by the model, such as those related to MSM sexual activity or relationships between PWID, are unavailable or unlikely to be accurately determined in the real world. Model-simulated estimates of the reported incidence of CHC, CHC-induced DC, and CHC-induced HCC in Ontario, the percentage of MSM among men, and the percentage of PWID in the population were calibrated against observed reported cases and percentages in Ontario from 2006 to 2017, respectively 39,42,45 . Historical incidence data from 2018 to 2019 were used purely for validation.…”