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

Abstract

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 ~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.

FIGURE 1

The level of HCV care cascade engagement among key risk groups. Figure showing the population level HCV care cascade in Ontario (A) for all individuals ever diagnosed with hepatitis C from January 1999 onwards and alive up to December 2018 inclusive and stratified by (B) birth year, (C) immigrant status, and (D) residential instability. Abbreviations: AB, antibody; SVR, sustained virologic response.

FIGURE 2

Covariate -adjusted hazard ratios for engagement with key stages of the HCV care cascade. Figure showing the predictors associated with (A) time-to-HCV RNA testing among HCV antibody positive cases, (B) time-to-treatment initiation among HCV RNA positive cases, and (C) time-to-SVR among HCV treated cases. Cause-specific hazard models for time-to-event outcomes were used to estimate HRs adjusting for multiple predictors. Abbreviations: AB, antibody; ADG, aggregated diagnostic groups; DAA, direct-acting antiviral; DC, decompensated cirrhosis; SVR, sustained virologic response.