Treatment as Prevention Effective in Reducing HCV Incidence Rates

Professor Gregory Dore, PhD

A team of investigators led by Professor Gregory Dore, PhD, of The Kirby Institute, found that a direct-acting antiviral (DAA) treatment scale-up was associated with a reduced incidence of chronic hepatitis C virus (HCV) in prison, which the team said is indicative of the effect of HCV treatment-as-prevention.

Data show DAA regimens are a well-tolerated, shorter pangenotypic treatment for chronic HCV, with cure rates greater than 95%.

Dore and colleagues noted that marginalized populations, including people who inject drugs, are incarcerated at high rates, while also at a higher burden of HCV infection and transmission.

Study

The investigators hypothesized that a rapid scale-up of direct-acting antiviral (DAA) treatment in prisons would reduce HCV transmission. Transmission was defined as incidence of primary HCV infection and re-infection.

As a result, the team used the SToP-C perspective study with a before-and-after analysis to evaluate the effect of HCV treatment-as-prevention.

Incidence rates of HCV were compared before and after rapid scale up of treatment, in 4 prisons in New South Wales, Australia. The prisons included 2 male maximum-security prisons and 2 medium security prisons, 1 male and 1 female.

Eligible participants for the study included any inmate ≥ 18 years old, regardless of HCV infection status, treatment history, risk behaviors, or sentence status.

After testing for HCV, participants in the study were monitored for risk behaviors and infection.

Investigators used 3 sub-populations, including uninfected (HCV antibody-negative), previous infected (HCV antibody-positive, HCV RNA-negative), and infected (HCV antibody and HCV RNA-positive).

Then, uninfected participants had a follow-up period every 3 – 6 months to detect HCV primary infection, while previously infected participants were followed up with every 3 – 6 months to detect re-infection.

Study participants with HCV infection were assessed for standard-of-care treatment from 2014 to mid-2017 and then DAA treatment scale up, with 12 weeks of sofosbuvir and velpatasvir, administered through SToP-C.

Participants were then followed up with until the study closure in November 2019.

The primary outcome of the study was HCV incidence rate ratio (IRR), a comparison of HCV incidence before and after DAA treatment scale-up among participants at risk of primary infection or re-infection.

Secondary outcomes included HCV treatment outcome.

Results

In the study period of October 2014 – September 2019, 3691 participants were enrolled, with 82% male and a median age of 33 years.

At study enrollment, 2240 participants (61%) had a negative HCV antibody test, 725 (20%) had a positive HCV antibody test and negative HCV RNA test, and 719 (19%) had a positive HCV RNA test.

DAA treatment scale-up included treatment of 349 (70%) of 499 participants, with 324 receiving treatment through SToP-C and 25 receiving treatment through the prison health service.

A total of 1643 participants at risk of HCV infection or re-infection were included in the HCV incidence analysis, with 487 (30%) reporting injecting drugs in prison.

The incidence rate of HCV decreased from 8.31 per 100 person-years during the study pre-treatment scale-up period to 4.35 per 100 person-years in the post-treatment scale-up period (incidence ratio ratio (IRR), 0.52; 95% CI, 0.36 – 0.78; P = .0007).

Investigators found the incidence of primary infection decreased from 6.64 per 100 person-years in the pre-treatment scale-up period to 2.85 per 100 person-years in the post-treatment scale-up period (IRR, 0.43; 95% CI 0.25 – 0.74; P = .0019).

The team also found the incidence of re-infection decreased from 12.36 per 100 person-years to 7.27 per 100 person-years (IRR, 0.59; 95% CI, 0.35 – 1.00; P = .050).

In participants who reported injecting drugs, the incidence of primary infection decreased from 39.08 per 100 person-years in the pre-treatment scale-up period to 14.03 per 100 person-years in the post-treatment scale-up period (IRR, 0.36; 95% CI 0.16 – 0.80; P = .0091).

In the same population, the incidence of re-infection decreased from 15.26 per 100 person-years to 9.34 per 100 person-years (IRR 0.61; 95% CI, 0.34 – 1.09; P = .093).

After adjusted analysis, investigators found a significant reduction found in the risk of HCV infection between the pre-DAA treatment scale-up and post-DAA treatment scale up period (hazard ratio 0.50; 95% CI, 0.33 – 0.76; P = .0014).

Conclusion

The team concluded that the SToP-C study provided evidence for the effectiveness of HCV treatment-as-prevention in the prison setting, supporting an enhancement in HCV treatment across populations of incarcerated people.

“The findings support enhanced delivery of DAA therapy for incarcerated populations, and suggest further consideration of HCV treatment-as-prevention strategies among the broader population at risk of HCV infection,” investigators wrote.

The study, “Evaluation of hepatitis C treatment-as-prevention within Australian prisons (SToP-C): a prospective cohort study,” was published in The Lancet Gastroenterology & Hepatology.