The National Health and Nutrition Examination Survey (NHANES) fails to capture the actual prevalence of HCV infection. Researchers developed two models to estimate US adult HCV prevalence from 2017 to 2020. Despite effective treatment availability for years, HCV prevalence stagnated during this period, due to increased injection drug use elevating estimates compared to 2013-2016. 1
The first approach (NHANES+) utilized methods to enhance HCV prevalence estimates among the US noninstitutionalized civilian population. Using the NHANES+ model, the estimated HCV RNA prevalence using the NHANES+ model was 1%, indicating approximately 2,463,700 current infections among US adults from 2017 to 2020. This model integrates data from a literature review and meta-analysis to enhance prevalence estimates among populations not adequately covered by NHANES sampling.1
With an estimated global impact of 58 million individuals, HCV infection typically arises from exposure to blood, commonly due to unsafe injection practices, inadequate healthcare, unscreened blood transfusions, injection drug use, and risky sexual behaviors involving blood exposure. The World Health Organization advises testing individuals at heightened risk of infection to facilitate early detection, which can prevent health complications and transmission. Some advocates suggest universal birth cohort screening to detect asymptomatic individuals unaware of their HCV status, although the cost-effectiveness of this approach remains uncertain and hinges on population prevalence.2
In the second approach persons who inject drugs (PWID) adjustment, a model was developed to address the underrepresentation of PWID in NHANES. This involved incorporating estimates of adult PWID in the US and applying HCV prevalence rates specific to this group. Using the PWID adjustment model, the estimated HCV RNA prevalence was higher at 1.6%, corresponding to approximately 4,043,200 current HCV infections.1
3 Key Takeaways
- NHANES underestimates HCV prevalence in the US, particularly among high-risk groups like PWID, prompting the development of more accurate estimation models.
- Despite the availability of effective treatments, the estimated prevalence of HCV from 2017 to 2020 in the US has shown no improvement, indicating a stagnation in efforts to reduce infection rates.
- Urgent national action is needed to expand testing, improve access to treatment, and enhance surveillance efforts, especially among medically underserved populations.
A similar dual study assesses the prevalence of HCV infection within the community, aiming to enhance clarity on prevalence rates, which may have been overestimated. The study revealed low levels of HCV seroprevalence and antigen positivity, suggesting that implementing universal birth cohort screening may not be necessary or cost-effective.
The first study analyzed residual serum samples from routine blood tests requested by general practitioners across eight hospitals. The second study utilized residual sera from SARS-CoV-2 testing among individuals over 18 years of age, sourced from the National Serosurveillance Program, which reflects the age distribution of the Irish population and includes individuals beyond the 1965–1985 birth cohort range.2
In the birth cohort study, two samples tested positive for HCV antigen. In the second study, with a broader age range, 10 samples were positive for HCV antigen, with 6 falling within the 1965–1985 birth cohort. Therefore, 8 individuals within the birth cohort tested positive for HCV antigen, resulting in a prevalence rate of .09%. Notably, the prevalence of HCV antigen was also .08% among the non-birth cohort group (4 out of 4973 samples) and the entire sample (12 out of 14,320 samples).2
“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.2
In summary, national action is needed to expand testing, improve access to treatment, and enhance surveillance, especially among medically underserved populations, to advance the goal of eliminating HCV. Understanding global trends can provide valuable insights into strategies for addressing HCV prevalence in the US.
References
Hall, E, Bradley H, Laurie K, et. al. Estimating Hepatitis C Prevalence in the United States, 2017–2020. Hepatology ():10.1097/HEP.0000000000000927, Published May 13, 2024. Accessed July 9, 2024. DOI: 10.1097/HEP.0000000000000927
