A review of general hepatitis C virus lookbacks in Canada
Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada. Vox Sanguinis
(Impact Factor: 2.8).
02/2004; 86(1):21-7. DOI: 10.1111/j.0042-9007.2004.00380.x
This article reviews the Canadian experience with general hepatitis C virus (HCV) lookback programmes.
Comprehensive literature searches were conducted in PubMed, Medline, HealthSTAR and EMBASE. In addition, bibliographic searches were performed on all retrieved articles, and provinces were contacted to determine whether they had performed general HCV lookbacks.
Of the seven Canadian general HCV lookbacks identified, two focused specifically on the paediatric population. The proportion of transfused patients presumed to be alive varied from 48.9 to 97.5%. Between 55.3 and 99.1% of letters were successfully delivered. The proportion of patients tested for HCV and subsequently found to be HCV positive varied considerably (66.2-80.4% and 0.9-5.0%, respectively). Newly diagnosed patients represented 42-58% of cases identified.
The Canadian general HCV lookback experience successfully identified previously undiagnosed HCV-positive patients, but the resources required to notify patients are high and the yield is relatively low. The effectiveness may be greatest in the paediatric population.
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- "HCV lookback was initiated in many countries shortly after the anti-HCV testing of donors had been introduced: 1990 in Holland (Vrielink, van der Poel et al. 1995), 1994 Scotland (Ayob, Davidson et al. 1994), 1995-97 England (NBS 2002), 1996 Denmark, 1994-99 Canada (Hume 2000); (Bowker, Smith et al. 2004), 1998 USA. So far only a limited directed HCV lookback has been performed in Sweden (Norda, Duberg et al. 1995; Foberg, Ekermo et al. 1996). "
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ABSTRACT: Integrated spread spectrum modem and digital voice processor designs can achieve processing gain adaptation without communication interruption. Only those adaptations that hold constant PN chip and/or FH hop rate to avoid modem resynchronization, are considered useful. Sync outages can render modem processing gain advantages ineffective. Variable chip embedding, data redundancy, and header insertion signaling techniques can modify modem processing gain without disturbing operation of the interfacing digital voice processor.
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ABSTRACT: The Centers for Disease Control and Prevention recommend hepatitis C virus (HCV) antibody (anti-HCV) screening for persons who received blood products before July 1992. A general transfusion lookback program was implemented to identify, counsel, and screen persons who received transfusions at the Alaska Native Medical Center between January 1980 and July 1992.
Hard-copy transfusion records data were entered, and available databases were queried to identify deceased patients and the mailing address of those living. Patients were notified by letter of their HCV risk and encouraged to seek counseling and testing. Serum samples were screened for anti-HCV and HCV RNA, and program costs were estimated.
Overall, 3169 transfusion recipients were identified, with 1356 (43%) living and targeted for notification. Of 764 patients notified and screened by this program, 41 (5%) were anti-HCV-positive and 19 (2%) were HCV RNA-positive. There was a higher probability of detecting anti-HCV with each subsequent increase of a transfusion event. Among 298 lookback patients, 33 percent were unaware of having received a blood transfusion. The estimated cost per person sent notification was US$57 and to detect an anti-HCV-positive case it was US$3146.
This general transfusion lookback program successfully notified and screened patients at a reasonable cost. Further investigation would be helpful in determining the role these programs or other measures could play in promoting HCV screening in persons receiving transfusions before July 1992, especially among those who are unaware of their transfusion history.
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