HCV Monitoring in Low-Risk, Undiagnosed Blood Donors Reveals Ongoing Untreated Infections

Sheila O’Brien, PhD, RN

Credit: Sheila O’Brien on LinkedIn

Despite being screened for hepatitis C virus (HCV) risk and having a lower prevalence of infection than the general population, findings from a recent study suggest blood donors mirror HCV trends in the general population and highlight the ongoing prevalence of untreated infections in groups less likely to have obvious risks for acquisition.¹

The study leveraged data for more than 2 million first-time donors from the Canadian Blood Services dataset and a case-control study of a subset of first-time donors between 1993-2021. During this 28-year span, the proportion of blood donors positive for HCV antibodies declined, although greater HCV positivity was observed among male patients, those born between 1945-1975, in the western provinces, and in those living in materially deprived and ethno-cultural concentrated neighborhoods.¹

According to the World Health Organization (WHO), globally, an estimated 50 million people have chronic HCV infection, with about 1 million new infections occurring per year. The WHO recommends focused or targeted testing of specific high-risk groups, including migrants from endemic regions; health-care workers; people who inject drugs; people in prisons and other closed settings; men who have sex with men; sex workers; and HIV-infected individuals. Individuals without these risk factors often are not the focus of HCV testing but may still be at risk of infection.²

“Blood donors are deferred for injection drug use, and sexual risks as well as cirrhosis, liver cancer, symptoms of hepatitis, and known HCV infection. As such, blood donors are a low-risk segment of the population who do not think they could have HCV and are unlikely to be tested in a clinical setting,” Sheila O’Brien, PhD, RN, associate director of epidemiology and surveillance for Canadian Blood Services and an adjunct professor at the University of Ottawa, and colleagues wrote.¹ “We have previously reported declining anti-HCV positivity in first-time blood donors from the implementation of testing up to 2005.”

To provide an additional 16 years of HCV prevalence in blood donors through 2021, investigators analyzed a pair of datasets including first-time blood donors in Canada. The first dataset was the Canadian Blood Services, which collects blood donations from all provinces in Canada except Quebec. All first-time blood donors from 1993-2021 were analyzed, with chronic HCV infection defined as persistent, detectable serum HCV RNA for > 6 months with or without derangement of liver function.¹

The second dataset was a case-control study from 2005-2021 of first-time donors with chronic HCV who were invited to participate in a telephone interview about risks for acquisition. HCV-positive donors (cases) since 2005 and HCV-negative donors (controls) matched for age, sex, and location were invited to complete a risk factor interview. For each case donor who participated, four control donors who had tested negative for HCV and all other markers matched according to age, sex, first-time donation status, and geographic region were randomly selected.¹

In total, 2,334,238 donors from 1993-2021 were included in the present analysis. Prevalence for HCV antibodies was 0.33% in 1993 and 0.07% in 2021 (P <.0001). Additionally, in 2021, investigators noted 0.03% of donors had chronic HCV.¹

Logistic regression analysis with chronic HCV as the dependent variable revealed significant main effects for being male (odds ratio [OR], 1.84; 95% CI, 1.60–2.13); both older birth cohorts, with the 1945-1975 birth cohort OR being greater than for those born before 1945 (born before 1945 OR, 4.40; 95% CI, 2.53–7.66; born 1945-1975 OR, 7.10; 95% CI, 5.92–8.52), British Columbia (OR, 1.44; 95% CI, 1.20–1.72) and Alberta (OR = 1.31, 95%CI 1.09–1.58) regions; and living in materially deprived neighborhoods (OR, 2.71; 95% CI, 2.12–3.45) and neighborhoods with ethnocultural concentration (OR, 1.78; 95% CI, 1.29–2.46).¹

Of 898 chronic HCV-positive donors invited to the case-control study, 318 (35.4%) participated. Of 3209 controls invited, 1272 (39.6%) participated. Upon analysis, the strongest risks for acquisition were a history of injection drug use (OR, 96.9; 95% CI, 22.3-420.3) and birth in a high prevalence country (OR, 24.5; 95% CI, 11.2-53.6).¹

Investigators acknowledged multiple limitations to these findings, including the observational nature of the study; the assumption that neighborhood indicators of material deprivation and ethnocultural status describe individuals and are representative of the wider community; the potential for participation bias in the case-control study; and some interview participants may not have disclosed all risks for acquisition due to stigma.¹

“In summary, blood donors are screened for HCV risks for acquisition and have lower prevalence than the general population,” investigators concluded.¹ “Nevertheless, donors largely mirror trends in the general population and highlight the ongoing prevalence of untreated infections in groups less likely to have obvious behavioral risks for acquisition.”

References

1. ^{O’Brien SF, Ehsani-Moghaddam B, Osmond L, et al. Epidemiology of Hepatitis C over 28 years of monitoring Canadian blood donors: Insight into a low-risk undiagnosed population. BMC Public Health. https://doi.org/10.1186/s12889-024-19790-2}
2. ^{World Health Organization. Hepatitis C. Newsroom. April 9, 2024. Accessed August 30, 2024. https://www.who.int/news-room/fact-sheets/detail/hepatitis-c}