Overestimation of HCV Prevalence Hinders Cost-Effectiveness of Universal Screening

Aiden McCormick

Credit: Irish Examiner

Findings from a pair of studies examining the community prevalence of hepatitis C virus (HCV) infection in Ireland suggest its prevalence may be overestimated, posing important implications about the need for and cost-effectiveness of universal birth cohort screening.¹

Results also called attention to a low proportion of hepatitis C antibody-positive patients with hepatitis C antigen, suggesting spontaneous clearance rates may be high and/or there has been a significant uptake of curative antiviral treatment in Ireland.¹

“The cost-effectiveness of screening is critically dependent on the population prevalence,” wrote Aiden McCormick, consultant hepatologist at St. Vincent’s University Hospital, and colleagues, highlighting the importance of accurate prevalence assessments for determining the viability of implementing a birth cohort HCV screening program.¹

Estimated to affect a global 58 million people, HCV infection often occurs through exposure to blood from unsafe injection practices, unsafe health care, unscreened blood transfusions, injection drug use, and sexual practices leading to blood exposure. The World Health Organization recommends testing people who may be at increased risk of infection to promote early diagnosis and subsequent prevention of related health problems and transmission. Some have gone even further and proposed universal birth cohort screening to identify asymptomatic individuals who may not know they have HCV, although the cost-effectiveness of this approach has not been confirmed and is dependent upon population prevalence.²

To determine the community prevalence of HCV infection, focusing specifically on the birth cohort 1965-1985, investigators conducted 2 studies. The first examined anonymized residual serum samples from general practitioner-requested blood tests in 8 hospitals. The second leveraged residual sera from SARS-CoV-2 testing from individuals > 18 years of age provided by the National Serosurveillance Program, reflecting the national age distribution of the Irish population and not restricted to the 1965–1985 birth cohort range.¹

A total of 14,320 samples were tested, 9347 of which were from the birth cohort 1965–1985. Investigators noted 72 samples were positive for hepatitis C antibody and 12 (17%) were positive for hepatitis C antigen.¹

In the birth cohort study, 2 samples were hepatitis C antigen-positive. In the second study, 10 samples were antigen-positive, 6 of which fell within the birth cohort age group. Thus, a total of 8 patients in the birth cohort were positive for hepatitis C antigen, corresponding to a 0.09% prevalence rate. Of note, the hepatitis C antigen prevalence was 0.08% in both the non-birth cohort (4/4973) and the total sample (12/14,320).¹

Investigators pointed out both HCV seroprevalence and the proportion of antibody-positive patients with hepatitis C antigen were lower than expected and previously estimated. Although the present studies posed notable strengths in their prospective, community-based design with a large sample size and wide geographical coverage, investigators were careful to note some high-risk populations may have been underrepresented and thus skewed the results.¹

Based on the results from the present study, investigators deduced national birth cohort screening is unlikely to be cost-effective but suggested birth cohort screening targeted at higher prevalence areas should be considered.¹

“The fact that only 17% of hepatitis C antibody–positive patients had hepatitis C antigen suggests that spontaneous clearance rates are high, or there has been a significant uptake of curative antiviral treatment or a combination of both. These results also suggest that Ireland is on track to achieve the WHO elimination targets for hepatitis C,” investigators concluded.¹

References:

1. ^{McCormick PA, O’Grady M, De Gascun CF, et al. Hepatitis C community prevalence is over-estimated: a prospective, birth cohort study. Ir J Med Sci (2024). https://doi.org/10.1007/s11845-023-03604-2}
2. ^{World Health Organization. Hepatitis C. Newsroom. July 18, 2023. Accessed February 8, 2024. https://www.who.int/news-room/fact-sheets/detail/hepatitis-c}