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

Background: 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's most populous jurisdiction. 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, 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 sustained virologic response, while similar to 1% experienced reinfection or relapse. Males, older birth cohorts, long-term residents, those with a history of substance use disorder and social marginalization (eg, 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 the province.