Abstract
Selection of voluntary donors who are at low risk of transfusion-transmissible viral infection (TTVI) is central in maintaining the safety of the blood supply. Evaluation of the effectiveness of donor selection and the dynamics of the process may offer opportunities to further improve transfusion safety. We analysed the impact of donor selection on the relative prevalence of TTVIs in all allogeneic donations in Australia between July 2000 and June 2006. We further explored the donor selection process where donors were found to have a TTVI despite pre-donation screening. Donors repeat reactive for a TTVI were offered counselling and confidential interview where potential infective risk exposures were reassessed, and disclosure of risk exposures at initial screening re-evaluated. 6,274,144 donations were received during the study period and tested for HCV, HBV, HIV, and HTLVI/II; of these, 1449 (0.02%) were repeat reactive for at least one TTVI and were discarded. Twenty-nice (2.5%) positive donors were not contactable or declined interview, giving an interview participation rate of 98.5%; all 1449 positive donors are included in the prevalence analysis. This comprised 605 (42%) positive for Hepatitis B; 818 (56%) positive for Hepatitis C; 18 (1%) positive for HIV; and 20 (1%) positive for HTLVI/II. The prevalence of HBV in accepted donors was at least 50 times lower than that in the Australian population; for HCV, 75 times lower; and HIV for 350 times lower. In new donors the prevalence was at least 6 times lower for HBV, 12 times lower for HCV and 140 times lower for HIV. In 1158 of 1420 donors interviewed (80%) an infective risk was identified; 509 donors (44%) had more than one risk. The most common identified were country of birth and parental ethnicity (N=682, 26% of reported risks); tattoos/piercings (N=448, 18%); and intravenous drug use (N=302, 12%). Other common risks included surgery or endoscopy (201 donors, 8%); receipt of blood products (N=144, 6%); and other blood contact, such as following sporting injuries (N=232, 10%). High-risk sexual contacts were uncommon risk exposures, but disproportionately significant in donors with HIV. Many of the identified risk exposures were temporally remote. The relative importance of risks varied significantly between TTVIs. In 302 cases (21%) disclosure of the identified risk exposures at pre-donation screening would have resulted in donor deferral. The proportion of positive donations which would not have been accepted had exposures been reported accurately was 3% for HBV; 35% for HCV; 39% for HIV; and 5% for HTLVI/II. Factors influencing non-disclosure included the temporal remoteness or isolated nature of the exposure, belief behaviour was not high-risk (eg, that needles were not shared during drug use), and perceptions that laboratory testing rendered disclosure unnecessary. Concerns about privacy or confidentiality of personal information were uncommon. These findings affirm the effectiveness of current stringent donor selection criteria in reducing the residual risk of TTVI. Ongoing donor education regarding the importance of risk disclosure is required. The development of screening criteria for use with emerging infections also offers continued opportunity for further improvements in transfusion safety.
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