The UK blood transfusion service: over a (patent) barrel?

Development of a nucleic acid lateral flow strip for detection of hepatitis C virus (HCV) core antigen

The object of this study was to develop a simple, rapid, specific, and highly sensitive method to detect HCV core antigen. A nucleic acid aptamer was designed with the high specificity and sensitivity in a nucleic acid lateral flow strip to compete with HCV core antigen and DNA probes. The lower detection limit of the test strip was calculated to be 10 pg/mL with the scanner and 100 pg/mL with naked eyes. Results showed that there were no cross-interactions with other proteins such as HCV NS3, E1/E2 antigens, HIV p24 antigens, or BSA proteins (HCV unrelated protein). When the viral load exceeded 10(4) copies/mL, the positive coincidence rates of ELISA and strip detection, when compared with the HCV RNA assay, were 98.44% and 97.28%, respectively. The results indicated that the ELISA detection and strip assay were in good agreement with the measured value. The results indicated that a nucleic acid lateral flow strip was a simple, rapid, specific, highly sensitive, and cost-effective field-based method for detecting HCV core antigen. The strip assay is an acceptable alternative to diagnose HCV core antigen and to investigate its epidemiology in clinical laboratories lacking specialized equipment and skills.

Hepatitis C virus core antigen assay: can we think beyond convention in resource limited settings?

Hepatitis C virus infects over 15 million patients from India and 2.86 million from Brazil. Detection of anti-hepatitis C virus antibodies has limited sensitivity during acute phase: the pre-seroconversion window period. Hepatitis C virus-RNA detection techniques are used to overcome this shortfall, but are costly and unavailable widely in developing countries. Estimation of hepatitis C virus core-antigen, a protein with highly conserved sequence, by enzyme-immunoassays is an economic and simpler alternative to RNA detection. This study was conducted in Delhi, involving 300 acute and chronic liver disease patients, tested for anti-hepatitis C virus 3rd-generation ELISA, hepatitis C virus core-antigen-ELISA and hepatitis C virus-RNA reverse transcription-polymerase chain reaction. Among the acute patients, hepatitis C virus core-antigen assay could identify 13 out of 14 pre-seroconversion window period cases and 6 out of 8 seroconverted cases, with a pre-seroconversion window period sensitivity of 92.9% and specificity of 100%. In hepatitis C virus core-antigen-positive cases, the viral load was in the range of 4900 to 1.46 × 10⁶ IU/mL, whereas in hepatitis C virus core-antigen-negative cases, the range of viral load was 100–4500 IU/mL. The cost of the hepatitis C virus core-antigen-ELISA was estimated around 3–4 times lesser than the in-house reverse transcription-polymerase chain reaction and 9–10 times lesser than the United States Food and Drug Administration approved reverse transcription-polymerase chain reaction. With a good sensitivity and specificity in the acute phase of infection, hepatitis C virus core-antigen-ELISA can thus be a useful alternative in the developing nations.

Comparison of monolisa HCV Ag/Ab ULTRA with two anti-HCV assays for the detection of HCV infection in hospital setting

In this study, we compared the performance of three serological assays (Monolisa HCV Ag/Ab ULTRA, Innotest HCV Ab IV enzyme immunoassay--EIA, and Ortho HCV 3.0 enzyme-linked immunosorbent assay--ELISA) for the detection of HCV infection. Ninety plasma samples were collected, representing 63 samples from groups at risk for acquiring HCV infection and 27 HCV RNA-positive samples. The results of Ortho HCV 3.0 ELISA, Innotest HCV Ab IV, and Monolisa HCV Ag/Ab ULTRA were fully concordant for 27 HCV RNA-positive samples. Ortho HCV 3.0 ELISA test and Innotest HCV Ab IV also gave the same results for risk groups, while three samples were found to be reactive by Monolisa HCV Ag/Ab ULTRA and were consequently found negative for HCV RNA. As two of the solely Monolisa HCV Ag/Ab ULTRA-positive samples were also hepatitis B s antigen (HBsAg)-positive, neutralization of HBsAg was performed but no arguments for the HBsAg interference were observed. In conclusion, the non-specific reactive signal was observed, in three samples using Monolisa HCV Ag/Ab ULTRA, to be negative by other serological assays, and observed to be negative in an HCV RNA assessment, a result that could not be attributed to the interference with HBsAg. In the context of diagnostic testing, no test for various HCV genotypes was observed to be superior to any other.

Antibodies to a novel antigen in acute hepatitis C virus infections

BACKGROUND

Conformational viral proteins potentially play an important role in the immunobiology of acute hepatitis C virus (HCV) infection and may enable earlier antibody detection.

MATERIALS AND METHODS

HCV RNA was detected using nucleic acid testing. Early antibody production was evaluated using three enzyme immunoassays (EIAs) containing antigenic proteins not present in licensed EIAs. Respectively, these contained: (1) multiple-epitope fusion antigen (MEFA) 7.1-NS3/4a, (2) F and Core, and (3) E1/E2 proteins. NS3/4a is a conformational antigen retaining protease and helicase enzymatic activities. MEFA 7.1 contains the linear epitopes used in licenced EIAs, including the latest EIA-3.0, in combination with genotype 1-3 specific epitopes. Forty-two RNA positive, EIA-3.0 negative samples, including two persistently serosilent cases, were used to evaluate these research EIAs. As controls, 54 EIA-3.0 negative/RNA negative and three HCV RNA+/antibody positive specimens were included.

RESULTS

Only the MEFA 7.1-NS3/4a EIA was positive in seven (17%) of the 42 HCV RNA + specimens, in all three EIA-3.0 positive controls but in none of 54 EIA-3.0 negative/HCV RNA negative controls. Notably, six of the seven (86%) specimens had evidence of active hepatitis (ALT > 210 IU/l). The two serosilent cases were research EIA negative.

CONCLUSION

A novel EIA with conformational and linear epitopes detected HCV antibodies in 17% of viraemic specimens missed by the standard reference EIA-3.0. Our research EIA appears to detect HCV antibodies closer to the initiation of acute hepatitis. Given that the average RNA-positive, antibody-negative window period is 56.4 days, this 17% yield would translate into a 10-day earlier detection of antibodies.

Twenty-four mini-pool HCV RNA screening outside a blood transfusion setting: Results of a 2-year prospective study

The usefulness of 24 mini-pool hepatitis C virus (HCV) RNA screening was evaluated in a 2-year prospective study carried out on a total of 6432 consecutive anti-HCV negative specimens in a routine diagnostic laboratory setting. A total of 268 mini-pools were tested using an automated commercial PCR assay for qualitative detection of HCV RNA, with a lower limit of detection of 50 IU/ml. Eighteen (0.28%) anti-HCV negative/HCV RNA positive serum samples obtained from 12 patients (all intravenous drug users), were detected. Ten patients responded to an invitation for follow-up testing. Five, three and one patient seroconverted in the first, second and third follow-up sample, respectively. One patient had not seroconverted by the end of the study period. The interval between the first HCV RNA positive sample and the first anti-HCV positive samples was 24-192 days. The costs of detecting a single anti-HCV negative/HCV RNA positive sample and a single anti-HCV negative/HCV RNA positive patient using the 24 mini-pool HCV RNA screening strategy were estimated to be around euro 643 and 965, respectively. It was shown that screening for HCV infection using the 24 mini-pool HCV RNA screening strategy can also be both useful and cost effective outside a blood transfusion setting.

Transmission of hepatitis C virus by blood transfusions and other medical procedures: a global review

Hepatitis C virus (HCV) is a leading cause of chronic blood-borne infection and chronic liver disease. The global epidemic of HCV infection emerged in the second half of the 20th century, and several lines of evidence indicate that it was primarily triggered and fed iatrogenically by the increasing use of parenteral therapies and blood transfusion. In developed countries, the rapid improvement of healthcare conditions and the introduction of anti-HCV screening for blood donors have led to a sharp decrease in the incidence of iatrogenic hepatitis C, but the epidemic continues to spread in developing countries, where the virus is still transmitted through unscreened blood transfusions and non-sterile injections. This article reviews the published literature concerning HCV transmission through blood transfusions and other unsafe medical procedures. Given the substantial difference in current disease transmission patterns between the northern and southern hemispheres, the situation in developed and developing countries is separately analysed.

Globalization and blood safety

Globalization may be viewed as the growing interdependence of countries worldwide through the increasing volume and variety of cross‐border transactions in goods and services, and also through the more rapid and widespread diffusion of technology. Globalization is not just an economic phenomenon, although it is frequently described as such, but includes commerce, disease and travel, and immigration, and as such it affects blood safety and supply in various ways. The relatively short travel times offered by modern aviation can result in the rapid spread of blood‐borne pathogens before measures to counteract transmission can be put in place; this would have happened with SARS if the basic life cycle of the SARS virus did not include an asymptomatic viraemia. This risk can be amplified by ecological factors which effect the spread of these pathogens once they are transferred to a naïve ecosystem, as happened with West Nile virus (WNV) in North America. The rationalization and contraction of the plasma products industry may be viewed as one aspect of globalization imposed by the remorseless inevitability of the market; the effect of this development on the safety and supply of products has yet to be seen, but the oversight and assurance of a shrinking number of players will present particular challenges. Similarly, the monopolization of technology, through patent enforcement which puts access beyond the reach of developing countries, can have an effect on blood safety. The challenges presented to blood safety by globalization are heightening the tensions between the traditional focus on the product safety – zero‐risk paradigm and the need to view the delivery of safe blood as an integrated process. As an illustration of this tension, donor deferral measures imposed by globalization‐induced risks such as vCJD and WNV have resulted in the loss of the safest and most committed portion of the blood donor population in many Western countries, leading to an increased risk to safety and supply. It is only through an appreciation of the basic needs of transfusion medicine, including the enunciation of appropriate principles to manage, rather than eliminate, risks, that the challenges imposed by globalization may be overcome.

A prospective study investigating the cost effectiveness of intraoperative blood salvage during liver transplantation

BACKGROUND

Adult orthotopic liver transplantation is associated with significant use of allogenic blood products, which places considerable demands on finite resources. This could be reduced by autologous red cell salvage use, and we evaluated its cost effectiveness in this prospective study.

METHODS

Intraoperative autotransfusion was used in 660 adult liver transplant patients between January 1997 and July 2002. These included 134 with acute liver failure, 62 retransplants, 90 alcohol-related, 183 viral, 98 cholestatic chronic liver diseases, and 93 with other etiologies.

RESULTS

The total volume of red blood cells transfused was 3641+/-315 ml, 2805+/-234 ml, 2603+/-443 ml, and 2785+/-337 ml for alcohol-related, viral, cholestatic, and others, respectively. Low preoperative hemoglobin was significantly associated with higher intraoperative transfusion requirements. Blood volumes transfused at retransplantation were significantly higher (7077+/-1110 ml vs. 2864+/-138 ml; P<0.001) than for acute liver failure and chronic liver disease. Autologous blood volumes transfused were similar in all diagnostic groups, but were significantly greater in retransplantation (2754+/-541 ml vs. 1524+/-77 ml; P<0.01). Venovenous bypass was significantly associated with higher transfusion requirements. Total savings per case were similar for all diagnostic groups but were greater in cases of retransplantation (864+/-222 pounds (1235+/-317 US dollars) vs. 238+/-24 pounds (340+/-34 US dollars; P<0.001). With the use of autologous transfusion over the study period, a cost saving of 131,901 pounds (188,618 US dollars) was achieved.

CONCLUSIONS

Intraoperative red blood cell salvage and autologous transfusion is cost effective in adult liver transplantation. Currently, where optimum resource utilization and fiscal constraint are paramount in healthcare delivery, autologous transfusion is an important adjunct in liver transplantation.

Performance of ORTHO HCV core antigen and trak-C assays for detection of viraemia in pre-seroconversion plasma and whole blood donors

OBJECTIVE

Logistics and cost of nucleic acid amplification testing (NAT) screening preclude its current use in many developing countries. Development of hepatitis C virus (HCV) core antigen assays offer an alternative to NAT. We evaluated two specimen populations to assess the sensitivity, relative to NAT, of the HCV core antigen (HCVcAg) ELISA (enzyme-linked immunosorbent assay) test system and the trak-C assay: (1) plasma donor HCV NAT-conversion panels and (2) cross-sectional whole blood donor NAT yield specimens.

METHODS

Differential sensitivities among NAT (NGI; Chiron/Gen-Probe) and both HCVcAg assays (Ortho-Clinical Diagnostics, Rochester, NY) were evaluated using: (1) 102 serial ramp-up phase specimens from 37 plasma donor NAT-conversion panels (Alpha Therapeutic/BioClinical Partners); and (2) 42 cross-sectional whole blood donor NAT yield specimens (confirmed RNA positive, antibody negative) plus 54 NAT false-positive specimens (American Red Cross).

RESULTS

Viral load among the plasma donor NAT-conversion panels at the cutoffs for HCVcAg and trak-C assays were 32 000 copies/ml (95% confidence interval [CI] 8000-120 000) and 8000 copies/ml (95% CI: 2200-28 000), respectively. The mean (95% CI) difference in window period reduction compared to routine mini-pool NAT screening (estimated sensitivity 100 copies/ml) was delayed 5.2 days (2.2-7.6 days) for HCVcAg assay and 3.8 days (2.1-5.5 days) for the trak-C assay. Among the 42 NAT yield specimens, the HCVcAg assay detected 31 (74%) as core antigen-positive while the trak-C assay detected 37 (88%) as core antigen-positive. Viral loads for the five specimens not detected by the trak-C HCVcAg assay ranged from 100 to 7770 copies/ml. All 54 NAT false-positive specimens were non-reactive on both HCV core antigen assays.

CONCLUSION

These data indicate that the trak-C assay has sensitivity approaching routine mini-pool NAT screening for the detection of seronegative HCV infection. In the absence of routine NAT screening for early HCV infection, the use of an HCV core antigen assay should be considered.

Combination hepatitis C virus antigen and antibody immunoassay as a new tool for early diagnosis of infection

Reduction of the window period of hepatitis C virus (HCV) infection represents an important goal in the transfusional and diagnostic setting. A prototype assay designed to simultaneously detect circulating HCV antigen and anti-HCV, has been developed. Aim of this study was to evaluate the performance of this new assay in terms of specificity and sensitivity and to compare its efficacy with commercial assays. To evaluate the specificity of the assay, 400 samples from the general population and 100 'difficult' sera, negative for anti-HCV, were tested. To assess sensitivity, the new test was used on 76 PCR-positive and anti-HCV negative sera, seven natural or commercial seroconversion panels that included 17 RNA-positive and anti-HCV negative sera and 31 anti-HCV positive sera, 20 weak anti-HCV positive sera, 80 viraemic and anti-HCV-positive sera from patients infected with different subtypes and 10 sera from patients with HBV-HCV or HIV-HCV co-infections. Of 500 anti-HCV negative samples, 499 (99.8%) were negative with a cut-off index <0.5, while one sample was within the grey zone. Of the 93 HCV-RNA positive and anti-HCV negative sera from patients and panels, 85 (91.4%) resulted positive, and one had the cut-off index in the grey zone. The reduction in the diagnostic window period observed with the new test and HCV-RNA assays were equal, on average, to 24 and 34.4 days respectively. All anti-HCV positive sera were positive. The new assay shows high sensitivity and specificity and could be a useful tool not only in the diagnostic setting, where procedures to reduce the window period, such as antigen or HCV-RNA detection, are not currently recommended, but also in the screening of blood donations, when nucleic acid technologies is not feasible because of costs, organization, emergency and/or logistic difficulties.

Is an assay for simultaneous detection of hepatitis C virus core antigen and antibody a valuable alternative to nucleic acid testing?

BACKGROUND

A new enzyme immunoassay based on the simultaneous detection of nucleocapsid proteins of hepatitis C virus (HCV) and anti-HCV (Monolisa HCV antigen-antibody Ultra, Bio-Rad) was evaluated as an alternative to nucleic acid testing (NAT) for the diagnosis of HCV infection during the window period in blood donations.

STUDY DESIGN AND METHODS

The study included 107 sequential samples from 10 HCV seroconversion commercial panels; 81 samples were in the preseroconversion phase, and 26 were collected after seroconversion. All samples were tested with HCV antigen-antibody assay and the two minipool (MP) NAT procedures that are routinely used in France (transcription-mediated amplification in pools of 8 and COBAS AmpliScreen HCV test [Roche Diagnostic] in pools of 24 donations).

RESULTS

From the 44 samples collected during window period that were MP-NAT-positive, 31 (70.5%) were also positive with the Monolisa HCV antigen-antibody assay. The mean delay in detecting HCV infection between these two methods was 5.1 days (range, 0-24 days). The Monolisa HCV antigen-antibody assay led to a reduction in the window period of 26.8 days (range, 0-72 days). All samples collected after seroconversion were detected with the HCV antigen-antibody assay. The specificity analyzed in 2503 consecutive blood donations was estimated at 99.88 percent.

CONCLUSION

This new developed assay presents an improvement for the detection of HCV infection, especially in the early phase of infection when antibodies are undetectable. Although less sensitive than NAT, this assay could be a suitable solution for blood screening in developing countries where NAT (or HCV core antigen-specific assay) is not affordable or its implementation is not feasible.

Residual risk of transfusion transmitted human immunodeficiency virus, hepatitis B virus, hepatitis C virus and human T lymphotrophic virus

BACKGROUND

The risk of transfusion transmitted viral infection is now so low that mathematical modelling is required to estimate the residual risk. The first national viral risk estimates for hepatitis B virus (HBV), human immunodeficiency virus (HIV) and hepatitis C virus (HCV) were recently published by the Australian Red Cross Blood Service. Using several refinements to the original methodology, as well as an additional 2 years of data, new risk estimates have been derived.

METHODS

Viral screening data for Australian donors for 2000/2003 were retrospectively analysed. The data were applied to three published models to estimate the residual risk of transmitting HIV, HBV, HCV or human T lymphotrophic virus (HTLV) by blood transfusion in Australia.

RESULTS

Applying the three models to HBV, HIV and HCV, three point estimates of the residual risk per unit were calculated for each virus. The median point estimates were 1 in 1,339,000 for HBV, 1 in 1 in 7,299,000 for HIV, and 1 in 3,636,000 for HCV. Although the HTLV risk could not be equivalently calculated because of the lack of incident infection it was estimated to be considerably less than 1 in 1,000,000 using a separate method.

CONCLUSIONS

The most current and accurate estimate of residual risk of viral transmission in Australia has been provided in the present study. The residual risk in Australia is exceptionally small, continuing to decrease and is generally less than European or US risk estimates. These new estimates demonstrate that for viral transmission the Australian blood supply is amongst the safest in the world, and provide a basis for evaluating the cost benefit of future viral testing methodologies.

Detection of HCV and HIV-1 antibody negative infections in Scottish and Northern Ireland blood donations by nucleic acid amplification testing

BACKGROUND AND OBJECTIVES

To reduce the risk of transfusion-transmissible viruses entering the blood supply, the nucleic acid amplification testing (NAT) was implemented to screen Scottish and Northern Irish blood donations in minipools. After 5 years of NAT for hepatitis C virus (HCV) and 2 years for human immunodeficiency virus-1 (HIV-1), the yield of serologically negative, nucleic acid positive 'window donations' and cost-benefit of NAT is under review.

MATERIALS AND METHODS

When the Scottish National Blood Transfusion Service (SNBTS) implemented NAT in 1999, a fully automated 'black box' system was not available. Therefore, an 'in-house' assimilated NAT assay was developed, validated and implemented. The system is flexible and allows testing for additional viral markers to be introduced with relative ease.

RESULTS

The HCV and HIV NAT assays have 95% detection levels of 7.25 IU/ml and 39.8 IU/ml, respectively, as determined by probit analysis. One HCV (1 in 1.9 million) and one HIV (1 in 0.77 million) window donation have been detected in 5 and 2 years, respectively, of NAT.

CONCLUSION

The SNBTS NAT assays are robust and have performed consistently over the last 5 years. The design of the in-house system allowed HIV NAT to be added in 2003 at a relatively small additional cost per sample, although for both assays, the royalty fee far exceeds the cost of the test itself. Clearly NAT has a benefit in improving the safety of the blood supply although the risks of transfusion-transmitted viral infections, as reported in the Serious Hazards of Transfusion (SHOT) report, are extremely low. Also, in UK the yield of HCV antibody negative, NAT positive donations is far lower than predicted although the early detection of an HIV window period donation and the increase of HIV in the blood donor and general populations may provide a stronger case for HIV NAT. SUMMARY SENTENCE: The yield of HCV and HIV NAT in UK is significantly less than that anticipated from statistical models.

Simultaneous detection of hepatitis C virus (HCV) core antigen and anti-HCV antibodies improves the early detection of HCV infection

To evaluate whether a new enzyme immunoassay developed for the simultaneous detection of hepatitis C virus (HCV) core antigen (Ag) and anti-HCV antibodies (anti-HCV Ab) (Monolisa HCV Ag/Ab ULTRA; Bio-Rad) could improve the early detection of HCV infection, we compared its sensitivity to that of anti-HCV, HCV core Ag, and HCV RNA assays. The populations studied included 12 blood donor samples positive for HCV RNA and HCV core Ag but negative for anti-HCV antibodies and 23 hemodialysis patients who developed anti-HCV Ab (seroconversion) during the follow-up. From these 23 individuals, 83 samples sequentially collected prior to seroconversion and 108 samples collected after seroconversion were tested. Six of 12 blood donations were positive by the HCV Ag/Ab assay. In the hemodialysis cohort, the 24 HCV RNA-negative samples were negative by the HCV Ag/Ab assay and 23 of the 59 HCV RNA-positive samples (39%) were positive. The HCV Ag/Ab assay detected HCV infection on average 21.6 days before the most sensitive antibody assay. The HCV Ag/Ab assay did not detect HCV infection as early as the HCV RNA assay (mean delay, 30.3 days) or HCV Ag assay (mean delays, 27.9, and 16.3 days by the HCV core Ag quantification assay and the HCV Ag blood screening assay, respectively). This new assay provides a notable improvement for the early detection of HCV infection during the so-called window period compared with anti-HCV Ab assays and could be a useful alternative to HCV RNA detection or HCV core Ag assays for diagnosis or blood screening when nucleic acid technologies or HCV core Ag detection are not implemented.

The role of core antigen detection in management of hepatitis C: a critical review

Several assays in research format and two commercial assays for the detection of hepatitis C virus (HCV) core protein or HCV core antigen have been developed in recent years. In order to elucidate the role and significance of HCV core antigen detection in the diagnosis and management of hepatitis C, we reviewed 56 studies published in peer-reviewed journals until September 2004. Evaluations in transfusion settings showed that the HCV core antigen assay detects HCV infection, similarly as nucleic acid techniques (NAT), between 40 and 50 days earlier than the current third generation HCV antibody screening assays. HCV core antigen levels closely track HCV RNA dynamics, and allow clinical monitoring of a patient's therapy, independently of HCV genotype, however, mainly in the samples with HCV RNA levels above 20,000 IU/ml. Considering the lower sensitivity of HCV core antigen detection in comparison to NAT, the HCV core antigen assay is not practical for the determination of the end of treatment response and sustained viral response, but could be useful for the determination of early viral response in the pegylated interferon-alpha and ribavirin treated patients infected with HCV genotype 1. The HCV core antigen detection is a viable tool for study of hepatitis C pathogenesis. The HCV core antigen can be used as a marker of HCV replication in anti-HCV positive individuals in the areas of the world that cannot afford NAT and/or in the settings that are not equipped or competent to perform HCV RNA testing. Because the manufacturer of HCV core antigen assays recently stopped an active marketing of these assays in several countries, it will, unfortunately and probably, never be possible to determine the actual potential and usefulness of HCV core antigen testing in the management of hepatitis C.

Evaluation of a total core antigen assay for the diagnosis of hepatitis C virus infection in hemodialysis patients

Hemodialysis patients are recognized as a group at high risk of infection with hepatitis C virus (HCV). Therefore, such a population should be screened routinely for the presence of HCV viremia. Since nucleic acid techniques remain expensive and largely unavailable in many laboratories in the developing world, the present study assesses the clinical usefulness of the HCV core antigen enzyme immunoassay for the diagnosis of HCV infection in dialysis patients. One hundred seventy-five dialysis patients were screened for the presence of anti-HCV antibodies and HCV RNA in the serum. One hundred twenty-eight serum samples were collected from the 76 patients who were anti-HCV antibody- and/or HCV RNA-positive. These were evaluated for total HCV core antigen. Of these samples, 55 had sufficient volume to be further tested to quantify HCV RNA by reverse transcription polymerase chain reaction (RT-PCR). Genotyping of the HCV strains showed that the majority belonged to genotype 1b (77%). The HCV core antigen assay showed a sensitivity and specificity of 84% and 89%, respectively. The use of core antigen assay has enabled the early detection of three patients who developed an acute hepatitis C infection during the period of study. A correlation study was undertaken between the quantitative values of viral load, expressed as pg/ml of HCV core antigen in serum, and viral RNA in UI/ml. A significant correlation was observed (Pearson's correlation coefficient: 0.552; P<0.001). In conclusion, detection of HCV core antigen in serum is an inexpensive, reliable, and highly specific assay that can be useful in most laboratory settings to diagnose HCV infection, and especially in laboratories where nucleic acid technologies are not yet available.

[Survival after blood transfusion: a study at Rouen university hospital]

The aim of this study was to estimate short term survival rate after blood transfusion according to various criteria.

PATIENTS AND METHODS

Patients admitted and transfused from January, 1 until June, 30 1996 at Rouen university hospital were retrospectively included, and their status (alive or dead) was determined. The characteristics of patients admitted and transfused were compared to the overall population of inpatients. Independent factors associated with mortality six months after blood transfusion were evaluated using Cox model.

RESULTS

During the study period, 1887 patients were transfused. These patients were older, more often admitted in surgical or in intensive care units, and had a longer duration of stay, than the overall inpatients population. The survival rate at six months in transfused patients was 76.1%. Mortality rate at six months was independently higher in patients aged 75 and older, in men, in patients admitted in intensive care units, or transfused with homologous fresh-frozen plasma or packed platelet blood cells. Mortality rate was lower in patients who underwent a surgical procedure, in children under 16, and in patients whose stay was classified in "Circulatory system disorders", "Musculoskeletal system and connective tissues disorders or trauma", or "Injuries, allergy or poisoning".

CONCLUSION

In this study implemented in a teaching hospital inpatients receiving blood transfusion, the survival was mainly associated with the severity and characteristics of the diseases requiring transfusion.

The rationale for pathogen-inactivation treatment of blood components

Blood transfusion provides an ideal portal of entry for microorganisms. Although current residual risks of microbial infection by transfusion are extremely low in the developed world, the requirements for even safer blood are paradoxically increasing. Such requirements are partly a legacy of the tragic transmissions of human immunodeficiency virus (HIV) by blood early in the acquired immunodeficiency syndrome pandemic and are legally expressed in consumer protection laws imposing strict product liability. Enhanced safety is called for, not only for recognized agents (especially bacteria, which cause most current transfusion-transmissible infections [TTIs]and have only recently been addressed) but also for potential future "emerging" TTIs. These possibilities are not merely theoretical. TTIs of HIV-1, HIV-2, hepatitis B virus vaccine escape mutants, human herpesvirus 8, West Nile fever virus, and variant Creutzfeld-Jakob disease amply demonstrate the continual emergence of such threats. For recognized agents, the possibilities of test errors, misreporting, process-control failures, and false-negative results (although rare with modern automation) remain. In principle, an all-embracing, pan-effective microbe-inactivation procedure offers a potential solution to blood safety concerns. Such procedures may also allow the removal of several existing antimicrobial interventions. However, blood services remain to be convinced that the various prerequisites for safe and effective pathogen inactivation have been met. Not the least of these prerequisites is that all blood components can be inactivated to provide a single streamlined alternative blood safety strategy. Furthermore, the huge potential value of effective pathogen-inactivation systems for developing countries should not be forgotten once such systems are perfected.

Long-term survival after blood transfusion: a population based study in the North of England

BACKGROUND

Blood transfusion may transmit infectious diseases with long incubation periods. Estimation of the risks of transmission of such disease requires know-ledge of long-term survival of transfused patients. No such information is available in the UK, where there is particular concern about possible transmission by trans-fusion of variant CJD.

STUDY DESIGN AND METHODS

Information on survival after transfusion and demographics was collected for all patients transfused during June 1994 in a population of 2.9 million served by a single blood center.

RESULTS

A total of 2899 patients were transfused with 10,760 units of RBCs (99% of RBCs issued during the study period). Follow-up to death or 5 years was completed for 98.2 percent, and 46.9 percent of all transfusion recipients were alive at 5 years; 41 percent of transfused RBC units and 36 percent of transfused FFP were given to patients who were alive at 5 years. Median age at transfusion was 67 years (mean, 60.9 years). Shorter patient survival was associated with increasing patient age, increasing numbers of RBC units transfused, trans-fusion of plasma or PLTs, and nonsurgical indications for transfusion.

CONCLUSIONS

Posttransfusion survival is lower than estimated in previous decades in other countries. This is probably due to a relative increase in use of transfusion for older patients and for medical indications. Our figures may be used to predict and stratify the risk of infections, such as variant CJD, amongst different groups of transfusion recipients.

Acute hepatitis C virus seroconversion in a Scottish blood donor: HCV antigen is not comparable with HCV nucleic acid amplification technology screening

BACKGROUND AND OBJECTIVES

This study was conducted to analyse the usefulness of hepatitis C virus (HCV) core antigen tests for the confirmation of HCV infection in a donor presenting as nucleic acid amplification technology (NAT) positive but negative for antibodies to HCV (anti-HCV).

MATERIALS AND METHODS

Blood donations were screened, in parallel, for anti-HCV using the Abbott PRISM HCV Chemiluminescent immunoassay (ChLIA) and an 'in-house' HCV NAT (pools of up to 95 donations). An HCV NAT-positive antibody-negative donor was identified. Twelve follow-up samples were obtained and tested with various HCV antigen (including the recently marketed Trak-C second-generation assay) and HCV antibody assays.

RESULTS

The single HCV NAT-positive, antibody-negative donation was identified from 1 117 681 donations screened in the 4-year period, July 1999 to June 2003. The index donation was positive by Ortho HCV core antigen enzyme immunoassay (EIA) and Ortho Trak-C (second-generation HCV core antigen EIA). An archive sample, taken 127 days prior to the index donation, was negative for all HCV markers. Subsequent samples demonstrated a loss of reactivity in the Ortho HCV core antigen EIA and reduced activity in the Ortho Trak-C until day 69. Immunoblot (Ortho RIBA-3) and HCV PRISM became positive on day 62, whilst Ortho HCV ELISA was not positive until day 132 or Biorad HCV ELISA until day 160. An alternative immunoblot (Innogenetics Innolia III) was positive from day 55. RNA levels fluctuated considerably during the follow-up period, being completely undetectable by routine screening methods at the time-point around seroconversion; subsequently, antibody was detected using all assays investigated.

CONCLUSIONS

This HCV-converting blood donor provided a unique panel of samples for using to assess current (and future) HCV assay systems. The overall test results led to the conclusion that individual HCV antigen testing should not be considered as equivalent to HCV NAT minipool screening. Trak-C antigen testing may be considered as a suitable confirmatory assay for isolated HCV NAT reactivity.

Cost-effectiveness of transfusion of platelet components prepared with pathogen inactivation treatment in the United States

Background: The Intercept Blood System (IBS) for platelets has been developed to reduce pathogen transmission risks during transfusions.

Objective: This study was a comprehensive economic analysis of the cost-effectiveness of using the IBS for single-donor apheresis platelets (AP) and random-donor pooled platelet concentrates (PC) versus AP and PC without the IBS in the United States in patient populations in which platelets are commonly transfused.

Methods: All data used in this analysis were summarized from existing published sources (primarily indexed in MEDLINE) and data on file at Baxter Healthcare Corporation (Chicago, Illinois) and Cerus Corporation (Concord, California). A literature-based decision-analytic model was developed to assess the economic costs and clinical outcomes associated with the use of AP and PC treated with the IBS for several conditions and procedures that account for a considerable proportion of the platelet usage in the United States: acute lymphocytic leukemia, non-Hodgkin's lymphoma, coronary artery bypass graft, and hip arthroplasty Risks of infection with HIV, hepatitis C virus (HCV), hepatitis B virus, human T-cell lymphotropic virus type 1, or bacterial agents were incorporated into the model. Possible benefits of reduction of the risk of emerging HCV like pathogens and elimination of the need for gamma irradiation were explored in sensitivity analyses.

Results: The incremental cost per quality-adjusted life-year gained by using AP + IBS versus untreated AP ranged from $1,308,833 to $4,451,650 (without bacterial testing) and $4,759,401 to $22,968,066 (with bacterial testing). Corresponding figures for PC + IBS versus untreated PC ranged from $457,586 to $1,816,060. Inclusion of emerging HCV like virus and the elimination of the need for gamma irradiation improved the cost-effectiveness to a range of $177,695 to $1,058,127 for AP without bacterial testing, $176,572 to $1,330,703 for AP with bacterial testing, and $22,888 to $153,564 for PC. The model was most likely to be affected by mortality from bacterial contamination, IBS effect on platelet utilization, and the inclusion of potential benefits (ie, gamma irradiation and/or emergent HCVlike virus). The model was relatively insensitive to changes in the IBS price and viral transmission risks.

Conclusions: The cost-effectiveness of pathogen inactivation via the IBS for platelets is comparable to that of other accepted blood safety interventions (eg, nucleic acid amplification technology). The IBS for platelets may be considered a desirable strategy to increase the safety of platelet transfusions and a potential insurance against the threat of emerging pathogens.

A new HCV core antigen assay based on disassociation of immune complexes: an alternative to molecular biology in the diagnosis of early HCV infection

BACKGROUND

An EIA based on immune complex disassociation of nucleocapsid proteins of HCV has been developed to detect and quantify HCV core antigen.

STUDY DESIGN AND METHODS

To evaluate whether this new assay (trak-C, Ortho Clinical Diagnostics) could be an alternative to NAT during the window period, its sensitivity in this context was assessed, and its performance was compared with that of a first-generation HCV core antigen assay dedicated to the blood screening (HCV core antigen ELISA). Studied populations included nine HCV RNA-positive, HCV antibody-negative blood donors and 23 hemodialysis patients who underwent an HCV seroconversion. From these individuals, 81 samples (23 HCV RNA-negative and 58 HCV RNA-positive) sequentially collected during the phase before seroconversion were tested.

RESULTS

The nine blood donor samples were positive for the presence of HCV core antigen by the trak-C, and 6 of 8 tested were positive for the presence of HCV core antigen by blood screening ELISA. In the hemodialysis cohort, the 23 HCV RNA-negative samples were negative with the two HCV core antigen assays. Among the 58 HCV RNA-positive samples, 46 of 57 (80.7%) tested were positive for the presence of HCV core antigen with the blood screening assay, and 57 of 58 (98.2%) were positive for the presence of HCV core antigen with the trak-C. The mean delays in detecting HCV infection between trak-C and the appearance of HCV antibodies, between HCV RNA testing and trak-C, and between trak-C and HCV core antigen ELISA were 58.2, 0.24, and 3.33 days, respectively.

CONCLUSION

Trak-C was more sensitive than the blood screening assay and had similar performance to HCV RNA assay in the window period. Trak-C could constitute an alternative to NAT for the diagnosis of HCV infection during the window period, especially when molecular biology procedures cannot be implemented.

Making risk statements stick

Estimates of risk associated with blood transfusion are reported from a variety of sources using different numerical constructs. These data must be judged for validity and generalizability to facilitate decisions for interventions and to estimate potential benefits of interventions. Risk estimates reported in consistent terms, such as occurrences per million units transfused, will assist in comparisons of risks and the expected effect observed at the practitioner level. Use of the estimated number needed to treat puts the effect of an intervention in perspective for the individual practitioner and for national health authorities. We re-evaluated data reported from several recent studies of transfusion risk to highlight this approach. In the USA, the number needed to treat estimated to prevent one HIV transmission is 4.3 million (mini-pool NAT); to prevent one death from bacterial sepsis is 21 thousand (conversion to single donor platelets), and 16 thousand (bacterial screening of platelet concentrates). As interventions are continuing to drive infectious disease transmission rates lower and lower, expressing residual risk as the number needed to treat demonstrates that further improvements in safety are unlikely to be recognized at the local level even though the overall impact at the national level is significant.