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

Data for more than 2 million blood donors in Canada provides insight into HCV antibody positivity trends in this notoriously low-risk patient population.

Sheila O’Brien, PhD, RN | Credit: Sheila O’Brien on LinkedIn

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
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