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Risk of HIV infection from blood transfusion in Montreal
R S Remis1, G Delage, R W Palmer
1Department of Public Health Sciences, University of Toronto, Ont.
Objectives:
To determine the incidence (including associated donor characteristics and time trends) of HIV infection among repeat blood donors and to estimate the risk of HIV transmission from blood transfusion in Montreal and in Canada as a whole.
Design:
Retrospective cohort analysis.
Setting:
Montreal Centre Blood Transfusion Service.
Participants:
People who donated blood at least twice after Nov. 1, 1985, and at least once from Apr. 1, 1989, to Mar. 31, 1993.
Intervention:
Blood was screened for HIV by enzyme-linked immunosorbent assay and results were confirmed by Western blot analysis.
Outcome Measures:
Incidence density (the incidence rate per person-time) of HIV infection among repeat blood donors by sex, age group and region of residence, and incidence density and risk among first-time donors and for Canada as whole.
Results:
There were 200,196 eligible donors and 432,631 person-years (PY) of observation. From 1989 to 1993, there were 18 HIV seroconversions among repeat donors. The crude incidence density was 3.3 per 100,000 PY (95% confidence interval [CI] 1.8 to 5.4 per 100,000 PY); it was 4.9 per 100,000 PY among men and 0.61 per 100,000 PY among women. Age-specific incidence per 100,000 PY was 2.5 among those 12-29 years of age, 5.1 among those 30-49, 2.9 among those 40-49, and 1.4 among those 50 and older. Based on an estimated mean "window period" (from when a donor's blood is capable of transmitting HIV until detectable antibody appears) of 25 days, the current risk of HIV infection from repeat donors in the window period is estimated at 1 in 440,000. Inclusion of blood units from first-time donors produces an overall risk of 1 in 390,000 (95% CI 1 in 250,000 to 655,000). The estimated risk per blood unit in Canada as a whole is 1 in 913000 (95% CI 1 in 507,000 to 2,050,000).
Conclusions:
This "sentinel" population of repeat blood donors is subject to important trends in HIV spread. Therefore, estimating the incidence density of HIV infection in repeat donors provides insight into the epidemiologic characteristics of HIV infection at minimal expense. As a result of measures to improve blood safety, including HIV testing, the incidence of HIV infection among blood donors in Canada is low and the risk of HIV transmission from transfusion is extremely small, although not zero.
Insights
The incidence of human immunodeficiency virus (HIV) infection among repeat blood donors is low, with an estimated risk of transmission from transfusion being extremely small. Ongoing monitoring of blood donors provides valuable insights into HIV spread.
Area of Science:
- Epidemiology
- Infectious Diseases
- Public Health
Background:
- Repeat blood donors serve as a sentinel population for monitoring trends in human immunodeficiency virus (HIV) spread.
- Understanding HIV incidence in this group is crucial for assessing transfusion-transmitted HIV risk.
Purpose of the Study:
- To determine the incidence of HIV infection among repeat blood donors in Montreal.
- To estimate the risk of HIV transmission via blood transfusion in Montreal and Canada.
- To analyze donor characteristics and time trends associated with HIV infection.
Main Methods:
- Retrospective cohort analysis of blood donors from the Montreal Centre Blood Transfusion Service.
- Screening of blood for HIV using enzyme-linked immunosorbent assay (ELISA) and confirmation by Western blot.
- Calculation of incidence density and estimation of HIV transmission risk, considering the "window period".
Main Results:
- From 1989-1993, 18 HIV seroconversions occurred among 200,196 repeat donors (incidence density: 3.3 per 100,000 person-years).
- Higher incidence was observed in men (4.9/100,000 PY) compared to women (0.61/100,000 PY).
- Estimated risk of transfusion-transmitted HIV from repeat donors in the window period was 1 in 440,000; overall risk in Canada was 1 in 913,000.
Conclusions:
- Repeat blood donors offer valuable epidemiological insights into HIV spread at minimal cost.
- Blood safety measures, including HIV testing, have resulted in low HIV incidence among Canadian blood donors.
- The risk of transfusion-transmitted HIV in Canada is extremely low, though not entirely eliminated.
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