Cost-effectiveness of nucleic acid test screening of volunteer blood donations for hepatitis B, hepatitis C and human immunodeficiency virus in the United States

Occult hepatitis B virus infection in Thai blood donors

BACKGROUND

An evaluation by the National Blood Center, the Thai Red Cross Society, of two commercial multiplex nucleic acid tests (NATs; the Chiron PROCLEIX ULTRIO test and the Roche Cobas TaqScreen MPX test) for screening Thai blood donors for hepatitis B virus (HBV), hepatitis C virus, and human immunodeficiency virus Type 1 identified 175 HBV NAT-reactive/hepatitis B surface antigen (HBsAg)-negative donors. The classification of the HBV infection of these donors was confirmed by follow-up testing.

STUDY DESIGN AND METHODS

Index samples were tested for HBV serologic markers and HBV viral loads were determined. Donors were followed for up to 13 months and samples were tested with both NAT assays and for all HBV serological markers.

RESULTS

Of 175 HBV NAT-yield donors, 72 (41%) were followed. Based on the follow-up results, the majority of donors who were followed had an occult HBV infection (66.7%), followed by donors with a primary, acute infection (26.4%). The majority of donors in this latter group (20.8%) were in the window period. Three donors (4.2%), who were anti-HBs positive, had a reinfection or breakthrough infection.

CONCLUSION

The majority of donors detected during routine screening, who were HBsAg negative and NAT reactive, had an occult HBV infection, thus validating the decision to introduce NAT for blood donations in Thailand.

Natural history of hepatitis B virus infection: pediatric perspective

Hepatitis B virus (HBV) infection is an important disease globally. Chronic HBV infection may result in serious complications. Its transmission may be either perinatal or horizontal. Perinatal transmission is particularly important after the implementation of a universal vaccination program. Through either route, chronic carrier status is usually established in early childhood. The course of the disease course is determined by the host-virus interaction. The host's immune system initially tolerates the virus, and then gradually attempts to clear it. The virus, on the other hand, tries to avoid host immune system attack by a strategy involving targeted epitope mutations. By generating mutants, the virus can survive attacks from the host's immune system, enabling the infection to persist. Different individuals have different responses to HBV infection; genetic polymorphisms in cytokines, hormones, and other immune modulators may affect the final outcome of chronic HBV infection. Due to the implementation of a universal infant HBV vaccination program, HBV infection is now under control. Unfortunately, there still are some cases of vaccination failure. Very high maternal viremia, in utero infection, or escape mutants are possible reasons for vaccination failure. Immunocompromised hosts also risk vaccination failure. Blood or organ donors with occult HBV infection are possible sources for immunocompromised hosts. These victims of vaccination failure may exhibit a different disease course due to chronic HBV infection from those who acquired the infection before the universal vaccination era. The achievement of our ultimate goal of HBV elimination depends on a globally effective universal vaccination program, as well as the application of some novel successful medications to control those who are already infected.

Cost-effectiveness study comparing pharmaceutically licensed plasma for transfusion (OctaplasLG®) versus fresh frozen plasma (FFP) in critically Ill patients in the UK

This study evaluates the cost-effectiveness of OctaplasLG® (pharmaceutically licensed plasma for transfusion) versus fresh frozen plasma (FFP) in critically ill patients in the UK using a decision-analytic approach. Transfusion with OctaplasLG® resulted in 0.03 quality adjusted life years (QALYs) and 0.03 life years saved compared with FFP. The discounted cost per life year was £949 ($1504), and the discounted cost per QALY saved was £1030 ($1632) with OctaplasLG® in the UK. Based on a higher price of £70 ($111) for OctaplasLG® versus £28.42 ($45.04) for FFP, OctaplasLG® is considered to be cost-effective at a threshold of £30,000 ($47,548) per QALY.

Cost-effectiveness of pooled nucleic acid amplification testing for acute HIV infection after third-generation HIV antibody screening and rapid testing in the United States: a comparison of three public health settings

BACKGROUND

Detection of acute HIV infection (AHI) with pooled nucleic acid amplification testing (NAAT) following HIV testing is feasible. However, cost-effectiveness analyses to guide policy around AHI screening are lacking; particularly after more sensitive third-generation antibody screening and rapid testing.

METHODS AND FINDINGS

We conducted a cost-effectiveness analysis of pooled NAAT screening that assessed the prevention benefits of identification and notification of persons with AHI and cases averted compared with repeat antibody testing at different intervals. Effectiveness data were derived from a Centers for Disease Control and Prevention AHI study conducted in three settings: municipal sexually transmitted disease (STD) clinics, a community clinic serving a population of men who have sex with men, and HIV counseling and testing sites. Our analysis included a micro-costing study of NAAT and a mathematical model of HIV transmission. Cost-effectiveness ratios are reported as costs per quality-adjusted life year (QALY) gained in US dollars from the societal perspective. Sensitivity analyses were conducted on key variables, including AHI positivity rates, antibody testing frequency, symptomatic detection of AHI, and costs. Pooled NAAT for AHI screening following annual antibody testing had cost-effectiveness ratios exceeding US$200,000 per QALY gained for the municipal STD clinics and HIV counseling and testing sites and was cost saving for the community clinic. Cost-effectiveness ratios increased substantially if the antibody testing interval decreased to every 6 months and decreased to cost-saving if the testing interval increased to every 5 years. NAAT was cost saving in the community clinic in all situations. Results were particularly sensitive to AHI screening yield.

CONCLUSIONS

Pooled NAAT screening for AHI following negative third-generation antibody or rapid tests is not cost-effective at recommended antibody testing intervals for high-risk persons except in very high-incidence settings.

The cost-effectiveness of introducing nucleic acid testing to test for hepatitis B, hepatitis C, and human immunodeficiency virus among blood donors in Sweden

BACKGROUND

The purpose of this study was to estimate the cost-effectiveness of using individual-donor nucleic acid testing (ID-NAT) in addition to serologic tests compared with the sole use of serologic tests for the identification of hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) among blood donors in Sweden.

STUDY DESIGN AND METHODS

The two strategies analyzed were serologic tests and ID-NAT plus serologic tests. A health-economic model was used to estimate the lifetime costs and effects. The effects were measured as infections avoided and quality-adjusted life-years (QALYs) gained. A societal perspective was used.

RESULTS

The largest number of viral transmissions occurred with serologic testing only. However, the risks for viral transmissions were very low with both strategies. The total cost was mainly influenced by the cost of the test carried out. The cost of using ID-NAT plus serologic tests compared to serologic tests alone was estimated at Swedish Krona (SEK) 101 million (USD 12.7 million) per avoided viral transmission. The cost per QALY gained was SEK 22 million (USD 2.7 million).

CONCLUSION

Using ID-NAT for testing against HBV, HCV, and HIV among blood donors leads to cost-effectiveness ratios that are far beyond what is usually considered cost-effective. The main reason for this is that with current methods, the risks for virus transmission are very low in Sweden.

Level of evidence of the value of care in federally qualified health centers for policy making

THE PROBLEM

Community health centers (CHCs) are part of the United States' medical care safety net. Cost effectiveness is a critical element of value in today's health policy environment. Not all cost-effectiveness studies employ formal peer-reviewed methodologies. A review of the literature on CHCs' cost effectiveness is necessary to assess whether a higher level of evidence is needed to guide future policy.

PURPOSE

We sought to review the quality of the evidence on the economic value of CHCs and indicate whether a higher of level evidence would be useful for making policy.

KEY POINTS

Evidence exists to support the general value of care in CHCs, but no evidence comes from formal economic evaluations of CHC care.

CONCLUSION

More formal cost-effectiveness evaluations would enhance the economic argument for CHCs but will remain difficult to conduct and may be unnecessary in light of other work on the value of care in CHCs.

Nucleic acid testing (NAT) of organ donors: is the 'best' test the right test? A consensus conference report

Nucleic acid testing (NAT) for HIV, HBV and HCV shortens the time between infection and detection by available testing. A group of experts was selected to develop recommendations for the use of NAT in the HIV/HBV/HCV screening of potential organ donors. The rapid turnaround times needed for donor testing and the risk of death while awaiting transplantation make organ donor screening different from screening blood-or tissue donors. In donors with no identified risk factors, there is insufficient evidence to recommend routine NAT, as the benefits of NAT may not outweigh the disadvantages of NAT especially when false-positive results can lead to loss of donor organs. For donors with identified behavioral risk factors, NAT should be considered to reduce the risk of transmission and increase organ utilization. Informed consent balancing the risks of donor-derived infection against the risk of remaining on the waiting list should be obtained at the time of candidate listing and again at the time of organ offer. In conclusion, there is insufficient evidence to recommend universal prospective screening of organ donors for HIV, HCV and HBV using current NAT platforms. Further study of viral screening modalities may reduce disease transmission risk without excessive donor loss.

Why an alternative to blood transfusion?

Allogeneic blood transfusions have been associated with several risks and complications and with worse outcomes in a substantial number of patient populations and clinical scenarios. Allogeneic blood is costly and difficult to procure, transport, and store. Global and local shortages are imminent. Alternatives to transfusion provide many advantages, and their use is likely to improve outcomes as safer and more effective agents are developed.

Is dengue a threat to the blood supply?

Dengue is the most common arthropod-borne infection worldwide, affecting at least 50 million people every year and endemic in more than 100 countries. The dengue virus is a single-stranded RNA virus with four major serotypes. Infection with one serotype confers homotypic immunity but not heterologous immunity, and secondary infection with another serotype may lead to more severe disease. The major route of transmission occurs through the Aedes aegypti mosquito vector, but dengue has also been transmitted through blood transfusion and organ transplantation. Infection results in a spectrum of clinical illness ranging from asymptomatic infection, undifferentiated fever, dengue fever, dengue haemorrhagic fever (DHF) to dengue shock syndrome (DSS). Dengue is spreading rapidly to new areas and with increasing frequency of major outbreaks. A trend has also been observed towards increasing age among infected patients. This will impact blood supply availability as more blood donors are deferred because of dengue infection or exposure to infection. The risk of transmission through transfusion of blood from asymptomatic viraemic donors will also increase. Although screening tests for dengue and effective pathogen reduction processes are now available for the blood supply, the value of implementing these costly measures needs to be carefully considered. Demand for platelets and fresh frozen plasma will rise with increasing number of DHF/DSS. Evidence-based guidelines for the clinical use of these blood components in the management of patients with DHF/DSS have not been well established, and inappropriate use will contribute to the challenges faced by blood services.

Risk assessment and cost-effectiveness/utility analysis

Decision-makers at all levels of public health and transfusion medicine have always assessed the risks and benefits of their decisions. Decisions are usually guided by immediately available information and a significant amount of experience and judgment. For decisions concerning familiar situations and common problems, judgment and experience may work quite well, but this type of decision process can lack clarity and accountability. Public health challenges are changing as emerging diseases and expensive technologies complicate the decision-makers' task, confronting the decision-maker with new problems that include multiple potential solutions. Decisions regarding policies and adoption of technologies are particularly complex in transfusion medicine due to the scope of the field, implications for public health, and legal, regulatory and public expectations regarding blood safety. To assist decision-makers, quantitative risk assessment and cost-effectiveness analysis are now being more widely applied. This set of articles will introduce risk assessment and cost-effectiveness methodologies and discuss recent applications of these methods in transfusion medicine.

Transmission of human immunodeficiency virus and hepatitis C virus through liver transplantation

In November 2007, a liver transplant recipient was confirmed to have human immunodeficiency virus (HIV) and hepatitis C (HCV) infection after the organ procurement agency notified our institution that the donor has been HIV and HCV positive. We reviewed medical records and the collected blood sample results for HIV and HCV testing. A 66 year old female with nonalcoholic steatohepatitis cirrhosis underwent liver transplantation. The donor was a male who had sex with men who received multiple blood transfusions during resuscitation. Preoperative testing for HIV and HCV antibodies were negative for both donor and recipient. Ten months later, HIV and HCV were identified with nucleic acid testing in the recipient and in the stored donor sera. This is the first reported case of HIV transmission from solid organ transplantation in 20 years, and the first ever reported case of simultaneously transmitted HIV and HCV. The current case represents a high risk donor with newly-acquired HIV and HCV who transmitted the diseases during the window period of the infections. In this era of organ shortages one option would be avoidance of any high-risk donor organs. Another option would be to continue the use of such organs with appropriate informed consent, acknowledging the limitations of current screening tests for HIV and HCV. This report should serve as a wake-up call to the transplant community to consider revamping organ donor screening for HIV and HCV using nucleic acid testing as well as reconsidering the ongoing use of high-risk donors.

Cost-effectiveness of HIV screening of blood donations in Accra (Ghana)

OBJECTIVES

Areas with high HIV-incidence rates compared to the developed world may benefit from additional testing in blood banks and may show more favorable cost-effectiveness ratios. We evaluated the cost-effectiveness of adding p24 antigen, mini pool nucleic acid amplification testing (MP-NAT), or individual donation NAT (ID-NAT) to the HIV-antibody screening at the Korle Bu Teaching Hospital (Accra, Ghana), where currently only HIV-antibody screening is undertaken.

METHODS

The residual risk of HIV transmission was derived from blood donations to the blood bank of the Korle Bu Teaching Hospital in 2004. Remaining life expectancies of patients receiving blood transfusion were estimated using the World Health Organization life expectancies. Cost-effectiveness ratios for adding the tests to HIV-antibody screening only were determined using a decision tree model and a Markov model for HIV.

RESULTS

The prevalence of HIV was estimated at 1.51% in 18,714 donations during 2004. The incremental cost per disability-adjusted life-year (DALY) averted was US$1237 for p24 antigen, US$3142 for MP-NAT and US$7695 compared to the next least expensive strategy. HIV-antibody screening itself was cost-saving compared to no screening at all, gaining US$73.85 and averting 0.86 DALY per transfused patient. Up to a willingness-to-pay of US$2736 per DALY averted, HIV-antibody screening without additional testing was the most cost-effective strategy. Over a willingness-to-pay of US$11,828 per DALY averted, ID-NAT was significantly more cost-effective than the other strategies.

CONCLUSIONS

Adding p24 antigen, MP-NAT, or ID-NAT to the current antibody screening cannot be regarded as a cost-effective health-care intervention for Ghana.

Survival after blood transfusion

BACKGROUND

Long-term survival of transfusion recipients has rarely been studied. This study examines short- and long-term mortality among transfusion recipients and reports these as absolute rates and rates relative to the general population.

STUDY DESIGN AND METHODS

Population-based cohort study of transfusion recipients in Denmark and Sweden followed for up to 20 years after their first blood transfusion. Main outcome measure was all-cause mortality.

RESULTS

A total of 1,118,261 transfusion recipients were identified, of whom 62.0 percent were aged 65 years or older at the time of their first registered transfusion. Three months after the first transfusion, 84.3 percent of recipients were alive. One-, 5-, and 20-year posttransfusion survival was 73.7, 53.4, and 27.0 percent, respectively. Survival was slightly poorer in men than in women, decreased with increasing age, and was worst for recipients transfused at departments of internal medicine. The first 3 months after the first transfusion, the standardized mortality ratio (SMR) was 17.6 times higher in transfusion recipients than in the general population. One to 4 years after first transfusion, the SMR was 2.1 and even after 17 years the SMR remained significantly 1.3-fold increased.

CONCLUSION

The survival and relative mortality patterns among blood transfusion recipients were characterized with unprecedented detail and precision. Our results are relevant to assessments of the consequences of possible transfusion-transmitted disease as well as for cost-benefit estimation of new blood safety interventions.

Dengue virus in blood donations, Puerto Rico, 2005

BACKGROUND

A single instance of transfusion-transmitted dengue infection has been reported. The high incidence of dengue in endemic countries, the high proportion of asymptomatic infection, and the median 5-day viremia, however, suggest that transfusion-associated dengue transmission may be more widespread than documented.

STUDY DESIGN AND METHODS

The prevalence of dengue virus (DENV) RNA was determined in all blood donations to the American Red Cross in Puerto Rico from September 20 to December 4, 2005, using a specific type of nucleic acid amplification test called transcription-mediated amplification (TMA). TMA-positive donations were defined as those having two repeatedly reactive TMA results. TMA-positive donations were tested by enzyme-linked immunosorbent assay for immunoglobulin M (IgM) antibodies, by reverse transcription-polymerase chain reaction (RT-PCR), and by viral culture.

RESULTS

Twelve (0.07%) of 16,521 blood donations tested were TMA-positive. Four were positive by RT-PCR (DENV serotypes 2 and 3). Virus was cultured from 3 of 4 RT-PCR-positive donations. One of the 12 TMA-positive donations was IgM-positive. Only 5 donations remained TMA-positive when diluted 1:16, as is done for routine minipool screening for other transfusion-transmissible viral infections (hepatitis C, human immunodeficiency, West Nile viruses [WNVs]).

CONCLUSION

Nearly 1 in 1000 blood donations contained DENV RNA, and virus could be cultured from TMA-positive donations, suggesting a transfusion transmission risk similar to that which existed in the United States for WNV before universal donation screening. Similar to WNV, IgM antibody screening is likely to be ineffective, and some potentially infectious donations will be missed by minipool screening. Transfusion transmission should be considered in patients with dengue after blood transfusion.

Lessons from cost-effectiveness research for United States public health policy

The application of cost-effectiveness analysis to health care has been the subject of previous reviews. We address the use of economic evaluation methods in public health, including case studies of population-level policies, e.g., environmental regulations, injury prevention, tobacco control, folic acid fortification, and blood product safety, and the public health promotion of clinical preventive services, e.g., newborn screening, cancer screening, and childhood immunizations. We review the methods used in cost-effectiveness analysis, the implications for cost-effectiveness findings, and the extent to which economic studies have influenced policy and program decisions. We discuss reasons for the relatively limited impact to date of economic evaluation in public health. Finally, we address the vexing question of how to decide which interventions are cost effective and worthy of funding. Policy makers have funded certain interventions with rather high cost-effectiveness ratios, notably nucleic acid testing for blood product safety. Cost-effectiveness estimates are a decision aid, not a decision rule.

Residual infectious disease risk in screened blood transfusion from a high-prevalence population: Santa Catarina, Brazil

BACKGROUND

Infectious disease testing has improved but viral infection transmission through transfusion continues to occur. Residual risk, however, is now so low in some countries that it can only be estimated by mathematical modeling. With hierarchical Bayesian methods, this study estimates the residual risk of transfusion-transmitted infections in Santa Catarina, Brazil.

STUDY DESIGN AND METHODS

Data from the six state blood collection services covering Santa Catarina between 1998 and 2002 were used. Information was obtained on donor profiles, screening and confirmatory test results, and records of all allogeneic blood donations for repeat donors. Residual risk estimates of hepatitis B virus (HBV), human immunodeficiency virus (HIV), hepatitis C virus (HCV), and human T-cell leukemia virus (HTLV) were separately derived from posterior distributions of incidence rates and preseroconversion window-period lengths.

RESULTS

Estimated risks of a donation infectious for HBV and HIV entering the blood supply are 1:10,700 (95% confidence interval [CI], 1:4900-1:28,200) and 1:26,200 (95% CI, 1:14,800-1:64,100) donations, respectively. Estimated risks for HCV and HTLV were 1:19,300 (95% CI, 1:10,400-1:44,800) and 1:116,300 (95% CI, 1:40,200-1:1,000,000) donations, respectively. HBV risk is 1.8 times greater than HCV risk, 2.4 times greater than HIV risk, and 10.8 times that of HTLV. Actual risks would be lower due to immune recipients and subinfectious levels of undetected viremia.

CONCLUSION

The major factor contributing to risk differences between Santa Catarina and countries with similar testing regimes is the much higher source population diseases prevalence. Payoff for nucleic acid testing would be low, thus additional investment in safety should be based on studies of the cost-effectiveness of different strategies to reduce overall transmission.

A Systematic Review of Cost-Utility Analyses in HIV/AIDS: Implications for Public Policy

Objectives . To determine whether gaps exist in published cost-utility analyses as measured by their coverage of topics addressed in current HIV guidelines from the Department of Health and Human Services (DHHS). Design . A systematic review of US-based cost-effectiveness analyses of HIV/AIDS prevention and management strategies, based on original, published research. Methods . Predefined criteria were used to identify all analyses pertaining to prevention and management of HIV/AIDS; information was collected on type of strategy, patient demographics, study perspective, quality of the study, effectiveness measures, costs, and cost-effectiveness ratios. Results . One hundred and six studies were identified; 62 described strategies for averting new HIV infections, and 44 dealt with managing persons who are HIV positive. The quality of studies was generally high, but gaps were found in all studies. Especially common were omissions in reporting data abstraction methodology and discussions of direction and magnitude of potential biases. Among the 22 most highly rated papers (score of 90 or higher), only 1 was cited in the guidelines, and 3 papers reported on interventions that were superseded by newer approaches. Using a $100,000 threshold, the guidelines usually endorsed interventions found to be cost-effective. Exceptions included recommending postexposure prophylaxis (PEP) for populations in which PEP is unlikely to be cost-effective and not recommending primary resistance testing in treatment-naive persons, although the intervention was reported to have a cost-effectiveness ratio of less than $50,000. Conclusions . Despite an abundant literature on the cost-utility of HIV/AIDS-targeted strategies, guidelines cite relatively few of these papers, and gaps exist regarding assessments of some strategies and special populations.

Costs of needlestick injuries and subsequent hepatitis and HIV infection

BACKGROUND

Physicians, nurses and other healthcare workers (HCWs) are at risk of bloodborne pathogens infection from needlestick injuries, but costs of needlesticks are little studied.

METHODS

We used the cost-of-illness and incidence approaches. We used the perspective of the medical provider (medical costs) and the individual (lost productivity). Data on needlesticks, infections from hepatitis B and C (HBV, HCV) and human immune-deficiency (HIV) among HCWs, as well as data on per-unit costs were culled from research literature, Centers for Disease Control and Prevention reports, and Bureau of Labor Statistics reports. We also generated estimates based upon industry employment and scenarios for source-patients. These data and estimates were combined with assumptions to produce a model that generated base-case estimates as well as one-way and multi-way probabilistic sensitivity analyses. Future costs were discounted by 3%.

RESULTS

We estimated 644,963 needlesticks in the healthcare industry for 2004 of which 49% generated costs. Medical costs were $107.3 million of which 96% resulted from testing and prophylaxis and 4% from treating long-term infections (34 persons with chronic HBV, 143 with chronic HCV, and 1 with HIV). Lost-work productivity generated $81.2 million, for which 59% involved testing and prophylaxis and 41% involved long-term infections. Combined medical and work productivity costs summed to $188.5 million. Multi-way sensitivity analysis suggested a range on combined costs from $100.7 million to $405.9 million.

CONCLUSION

Detailed methodology was developed to estimate costs of needlesticks and subsequent infections for hospital-based and non-hospital-based health care workers. The combined medical and lost productivity costs comprised roughly 0.1% of all occupational injury and illness costs for all jobs in the economy. We did not account for lost home production or pain and suffering costs, however, nor did we estimate benefit/cost ratios of specific interventions to reduce needlesticks.

Legal, financial, and public health consequences of transfusion-transmitted hepatitis C virus in persons with haemophilia

BACKGROUND

Since the first cases of acquired immunodeficiency syndrome in persons with haemophilia were reported in 1982, much has been written about the consequences of human immunodeficiency virus (HIV) contamination of the blood supply. Relatively little attention has been paid to similar hepatitis C virus (HCV) concerns since the first cases of HCV-infected persons with haemophilia were identified in 1989.

METHODS

We review the history, public health, policy, and financial consequences of blood supply policy decisions made for persons with haemophilia who received HCV-contaminated blood products in eight countries that were severely impacted by viral contamination of the blood supply during the 1980s, contrasting these findings with those reported previously for HIV contamination of the blood supply during the same time-period. A Medline search and a hand search of retrieved bibliographies of English-language articles on HCV concerns in haemophilia patients published from 1989 to 2006 were performed.

RESULTS

Our review identified that two- to eightfold more persons with haemophilia in the eight countries contracted HCV vs. HIV from contaminated blood products during the 1980s. Opportunistic infections and immunosuppression-related complications among persons with haemophilia developed shortly after these patients received HIV-infected blood products whereas hepatic complications among HCV-infected persons with haemophilia are just now being diagnosed two decades after these individuals received HCV-contaminated blood products. Policy makers in four countries conducted official public inquiries into blood safety decisions related to HIV- and/or HCV-contamination of the blood supply. More than 20 countries allocated compensation funds for HIV-infected persons with haemophilia (mean award ranging from $37 000 to 400 000) whereas only the UK, Canada, and Ireland allocated compensation funds for HCV-infected persons with haemophilia (mean award ranging from $37 000 to 50 000).

CONCLUSION

While the clinical impact among persons with haemophilia of HCV contamination of the blood supply in the 1980s was larger than the impact of HIV contamination of the blood supply during this time-period, the policy response was smaller. Consideration should be given to adopting support programmes for HCV-infected persons with haemophilia in countries that do not have these programs.

Epidemiology of HBV infection in Asian blood donors: Emphasis on occult HBV infection and the role of NAT

Hepatitis B virus (HBV) infection is endemic in many Asian countries. Among many transmission routes, transfusion is the one that should be prevented. The first major success in enhancing transfusion safety came with the implementation of hepatitis B surface antigen (HBsAg) in the early 1970s. However, the studies quoted in this review demonstrate that transmission by blood components negative for HBsAg can still occur in the acute phase of infection during the seronegative window period, or during chronic stages of infection (i.c. "occult" HBV infection, OHB). OHB is defined as the presence of HBV DNA in blood or liver tissues in patients negative for HBsAg, with or without any HBV antibodies. Because of limitations in current blood screening practices, OHB is an overlooked source of HBV transmission. For policy development on screening for HBV infection in blood donors, it would be useful to assess the relative contribution of the above two sources of transfusion-transmitted HBV infection from HBsAg-negative donations. New screening policy should be evaluated on the basis of available data or newly designed studies. While anti-HBc screening can climinate residual risk of occult HBV transmission by transfusion in low-endemic areas, it would not be practical in most parts of the world where the prevalence of anti-HBc is >10% as too many otherwise healthy donors will be ineligible. On the contrary, studies mentioned in this paper indicate that nucleic acid amplification test (NAT) or new HBsAg tests of enhanced sensitivity would be effective in the screening of blood donors for OHB in highly endemic countries. However, the cost-effectiveness of blood screening tests is a major concern in Asia. We therefore have systemically reviewed the literature on prevalence and infectivity of OHB in Asian countries and the possible role of NAT for identifying blood donors in the pre-HBsAg window phase or in later stages of OHB.

Cost-effectiveness of alternative blood-screening strategies for West Nile Virus in the United States

BACKGROUND

West Nile virus (WNV) is endemic in the US, varying seasonally and by geographic region. WNV can be transmitted by blood transfusion, and mandatory screening of blood for WNV was recently introduced throughout the US. Guidelines for selecting cost-effective strategies for screening blood for WNV do not exist.

METHODS AND FINDINGS

We conducted a cost-effectiveness analysis for screening blood for WNV using a computer-based mathematical model, and using data from prospective studies, retrospective studies, and published literature. For three geographic areas with varying WNV-transmission intensity and length of transmission season, the model was used to estimate lifetime costs, quality-adjusted life expectancy, and incremental cost-effectiveness ratios associated with alternative screening strategies in a target population of blood-transfusion recipients. We compared the status quo (baseline screening using a donor questionnaire) to several strategies which differed by nucleic acid testing of either pooled or individual samples, universal versus targeted screening of donations designated for immunocompromised patients, and seasonal versus year-long screening. In low-transmission areas with short WNV seasons, screening by questionnaire alone was the most cost-effective strategy. In areas with high levels of WNV transmission, seasonal screening of individual samples and restricting screening to blood donations designated for immunocompromised recipients was the most cost-effective strategy. Seasonal screening of the entire recipient pool added minimal clinical benefit, with incremental cost-effectiveness ratios exceeding USD 1.7 million per quality-adjusted life-year gained. Year-round screening offered no additional benefit compared to seasonal screening in any of the transmission settings.

CONCLUSIONS

In areas with high levels of WNV transmission, seasonal screening of individual samples and restricting screening to blood donations designated for immunocompromised recipients is cost saving. In areas with low levels of infection, a status-quo strategy using a standard questionnaire is cost-effective.

Assessment of the economic value of the INTERCEPT blood system in Belgium

Emerging pathogens continue to threaten blood safety, requiring novel safety approaches. INTERCEPT Blood System for platelets (IBSP) inactivates pathogens, aiming at eliminating the risk of transmitting current and emerging pathogens. The objective was to evaluate the incremental cost-effectiveness ratio (ICER) for IBSP in Belgium. A decision model comparing a 'world with IBSP' to a 'world without IBSP' calculates lifetime costs and 'quality adjusted life years' (QALYs) following platelet transfusion in different indications. Disease-specific life expectancy and consequences of transfusion-transmitted infections were obtained from literature. Transfusion safety and costs were obtained from official sources. Hepatitis C virus-like emerging pathogen was simulated. A wide range of ICERs was observed, highly sensitive to the risk of emerging pathogen trans- mission, underlying disease and age. In the most conservative approach, ICER ranged from 3,459,201 Euro/QALY in absence of emerging pathogen to 195,364 Euro/QALY. The mean threshold of emerging infection risk for IBSP dominance (saving money and producing health gains) ranged from 1/1,079 to 1/2,858 transfusions. Considering the high value authorities appear to place on preventing accidental injury, and ICER of recent implementations in transfusion medicine (NAT: up to 2.3 million Euro per lifeyear), IBSP can be considered cost-effective, taking into account the potential risk of emerging pathogens.

Transmission of occult hepatitis B virus by transfusion to adult and pediatric recipients in Taiwan

BACKGROUND/AIMS

The infectivity of occult hepatitis B virus (HBV), defined as HBsAg-negative but HBV DNA-positive, after transfusion has been low but not negligible. To address this, we investigated the incidence of post-transfusion HBV infection after receiving screened blood units in Taiwan.

METHODS

Consecutive HBV-naïve (anti-HBc-negative) recipients with normal ALT were followed for HBV DNA and serologic markers before and after transfusion. Among 4448 blood recipients, 467 (10.5%) were anti-HBc-negative. Post-transfusion 6-month follow-up was completed for 327. We identified 5 (1.5%) who developed hepatitis B viremia 1 week after transfusion. Three were children who later seroconverted to anti-HBc but with normal ALT indicating subclinical acute infection, despite all had anti-HBs from previous vaccination. One had transient transfusion-transmitted HBV without seroconversion to anti-HBc and one possibly had occult HBV infection. Our findings suggested the possibility that occult HBV infection was transmissible by transfusion. The incidence of post-transfusion acute HBV infection was 0.9% (100 per million units) in naïve recipients in Taiwan, a figure 7 approximately 40-fold higher than in developed countries. Moreover, some vaccinated children with anti-HBs were still susceptible.

CONCLUSIONS

Therefore, despite active immunization, sensitive screening assays for occult HBV infection such as nucleic acid amplification test could be considered in endemic areas.

A multiplex polymerase chain reaction microarray assay to detect bioterror pathogens in blood

Heightened concern about the dangers of bioterrorism requires that measures be developed to ensure the safety of the blood supply. Multiplex detection of such agents using a blood-screening DNA microarray is a sensitive and specific method to screen simultaneously for a number of suspected agents. We have developed and optimized a multiplex polymerase chain reaction microarray assay to screen blood for three potential bioterror bacterial pathogens and a human ribosomal RNA gene internal control. The analytical sensitivity of the assay was demonstrated to be 50 colony-forming units/ml for Bacillus anthracis, Francisella tularensis, and Yersinia pseudotuberculosis (surrogate for Yersinia pestis). The absence of any false-positives demonstrated high analytical specificity. Screening B. anthracis-infected mouse blood samples and uninfected controls demonstrated effectiveness and specificity in a preclinical application. This study represents proof of the concept of microarray technology to screen simultaneously for multiple bioterror pathogens in blood samples.

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.

Relative sensitivities of licensed nucleic acid amplification tests for detection of viremia in early human immunodeficiency virus and hepatitis C virus infection

BACKGROUND

Screening donors for human immunodeficiency virus (HIV) and hepatitis C virus (HCV) RNA is primarily performed on minipools (MPs) with one of two commercial nucleic acid amplification tests (NAT; Roche Molecular Systems; or Gen-Probe/Chiron). We compared these assays with respect to detection of RNA in early HIV and HCV infection.

STUDY DESIGN AND METHODS

Twelve HIV plasma donor panels (116 serial samples) and 12 HCV panels (180 serial samples) were selected to optimally represent early viremia. Initial testing was performed in singlicate or triplicate on separately coded aliquots, both neat and at dilutions corresponding to MP screening (1:16 for Gen-Probe; 1:24 for Roche); 20 additional replicates were performed when discordant results were observed. Odds ratios (ORs) comparing detection of RNA by different assays were derived with logistic regression models. Differences in window-period closure and yields of assays in MP or individual-donation (ID) format were estimated.

RESULTS

Differences in detection rates between Roche and Gen-Probe NAT assays were small and only observed with samples with very-low-level viremia. ORs for detecting RNA by the Gen-Probe versus the Roche assay were significant for HIV if conducted on MPs (1.8; 95% confidence interval [CI], 1.3-2.5) but not neat (1.0; 95% CI, 0.72-1.4). Odds of detecting HCV RNA were higher if the Gen-Probe assay was conducted either neat (2.3; 95% CI, 1.6-3.2) or on MPs (4.0; 95% CI, 2.8-5.8). These differences translated to <1 day window-period closure and

CONCLUSIONS

Differences in sensitivities of licensed NAT assays for HIV and HCV are very small and clinically insignificant, particularly when compared to differences of MP versus ID NAT screening.

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Key Words Collapse

MESH Headings

• Blood Banking/methods
• HIV/genetics
• HIV/isolation & purification
• HIV Infections/blood
• HIV Infections/diagnosis
• Hepacivirus/genetics
• Hepacivirus/isolation & purification
• Hepatitis C/blood
• Hepatitis C/diagnosis
• Humans
• Licensure
• Mass Screening/methods
• Nucleic Acid Amplification Techniques/methods
• RNA, Viral/blood
• RNA, Viral/isolation & purification
• Sensitivity and Specificity
• Viremia/blood
• Viremia/diagnosis

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Grants

• N01-HB-47114 NHLBI NIH HHS
• N01-HB-97077 NHLBI NIH HHS
• N01-HB-97078 NHLBI NIH HHS
• N01-HB-97079 NHLBI NIH HHS
• N01-HB-97080 NHLBI NIH HHS
• N01-HB-97081 NHLBI NIH HHS
• N01-HB-97082 NHLBI NIH HHS

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Affiliation(s)

Michael P Busch Blood Systems Research Institute, San Francisco, California 94118, USA.
Simone A Glynn
David J Wright
Dale Hirschkorn
Megan E Laycock
Joan McAuley
Yongling Tu
Cristina Giachetti
James Gallarda
John Heitman
Steven H Kleinman

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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.

Reengineering transfusion and cellular therapy processes hospitalwide: ensuring the safe utilization of blood products

Efforts to make blood transfusion as safe as possible have focused on making the blood in the bag as disease-free as possible. The results have been dramatic, and the costs have been correspondingly high. Although blood services will have to continue to deal with emerging pathogens, efforts to reduce the transfusion of infectious agents presently posing a risk will require high incremental costs and result in only improvements of a small magnitude. The other aspect of safe blood transfusion, the actual transfusion process performed primarily in hospitals, has been accorded considerably less interest. We should turn our attention to enhancing overall blood safety by focusing on improving the process of blood transfusion. Errors involving patient, specimen, and blood product identification put transfused patients at risk, increasing the mortality risk for some. Solutions that could improve the transfusion process are discussed as a focus of this article.

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.

Hepatitis B virus (HBV) DNA screening of blood donations in minipools with the COBAS AmpliScreen HBV test

BACKGROUND

The risk of hepatitis B virus (HBV) transmission by blood transfusion (estimated at 1 in 63,000-1 in 205,000 units in the United States) exceeds that of hepatitis C virus (HCV) or human immunodeficiency virus (HIV). Reduction of window-period HBV transmissions through detection of HBV DNA-positive units by minipool nucleic acid testing (MP NAT) would be expected to decrease this risk.

STUDY DESIGN AND METHODS

A large multicenter study of the COBAS AmpliScreen HBV test (Roche Molecular Systems) was conducted on minipools of 24 blood donation specimens. The yield of HBV DNA-positive, hepatitis B surface antigen (HBsAg)-negative window-period donations was determined relative to current and newly licensed HBsAg assays. Donors with selected HBV DNA, HBsAg, and anti-hepatitis B core antigen (HBc) results were further evaluated.

RESULTS

The detection rate of window-period units was 1 in 352,451 (95% confidence interval, 1 in 2,941,176-1 in 97,561). Assay specificity was high (99.9964%). HBV DNA was detected in 84 percent of HBsAg-positive, anti-HBc-positive donations by MP NAT and in 94 percent when individual-donation (ID) NAT was added. HBV DNA was detected in 0.03 percent of HBsAg-negative, anti-HBc-positive donations by MP NAT and in 0.41 percent when ID NAT was added.

CONCLUSIONS

Implementation of HBV MP NAT will provide an increment in safety relative to HBV serologic screening, similar to that for HCV and in excess of that for HIV. Our data indicate that the implementation of HBV MP NAT would likely interdict 39 HBV window-period units and prevent 56 cases of transfusion-transmitted HBV infection annually. The current data indicate that HBV MP NAT should not lead to discontinuation of anti-HBc testing but that discontinuation of HBsAg testing with retention of anti-HBc testing may be possible.

High-throughput purification of viral RNA based on novel aqueous chemistry for nucleic acid isolation

BACKGROUND

Extraction protocols using magnetic solid phases offer a high potential for automation. However, commercially available magnetic-bead-based assays either lack the sensitivity required for viral diagnostics or are disproportionately expensive.

METHODS

We developed an aqueous chemistry for extraction of viral nucleic acids from plasma samples by use of common magnetic silica beads. Nucleic acids were bound to the beads at acidic conditions in the presence of a kosmotropic salt and were eluted at a slightly alkaline pH. The method was implemented on a standard pipetting workstation for fully automated extraction of up to 48 samples of 240 muL plasma in 1 batch.

RESULTS

The detection limit of the method was comparable to the spin-column-based QIAamp Viral RNA Mini Kit, which relies on chaotropic salts and binding to a silica membrane, as the comparison method. The 95% detection limit was 23.1 IU per PCR for HIV-1 and 10.7 IU per PCR for hepatitis C virus (HCV). Suitability for clinical routine testing was confirmed in a total of 178 HIV-1- or HCV-positive plasma samples. The method linearity (R(2)) was >0.99 for the viruses evaluated.

CONCLUSIONS

Use of reagents without organic solvents allows simple and cost-effective automation of this method on common pipetting robots with low risk of contamination. Performance characteristics of the novel extraction method make it suitable for use in diagnosis of infectious diseases and viral load determinations.

Screening the blood supply for West Nile virus RNA by nucleic acid amplification testing

BACKGROUND

The use of nucleic acid amplification tests of "minipools" of 16 samples to screen blood donors for West Nile virus RNA began in July 2003. We report the yield and characteristics of positive donations and the incremental yield and safety of nucleic acid amplification tests of individual donations.

METHODS

Reactive minipools were analyzed to identify the individual reactive donations. For the regions with the highest yield on minipool testing, retrospective nucleic acid amplification testing was performed on individual donations that were negative on minipool testing. Reactive donations were confirmed by alternative nucleic acid amplification tests and IgM and IgG tests, and donors were followed to document seroconversion.

RESULTS

From July 1 through October 31, 2003, 677,603 donations were prospectively screened for West Nile virus by minipool testing, yielding 183 confirmed viremic donations (0.027 percent, or 1 in 3703 donations). Retrospective individual testing of 23,088 donations from high-prevalence regions that were negative on minipool testing yielded 30 additional units with a low level of viremia, with 14 additional viremic units detected by prospective testing of individual donations late in the 2003 transmission season. Of all the viremic units detected, 5 percent were detected only by individual testing and were negative for IgM antibody, 29 percent were detected by individual testing after IgM seroconversion, and 66 percent were detected by minipool testing. West Nile virus infection was confirmed in both recipients of IgM-negative units that were reactive on individual testing, whereas neither recipient of antibody-positive blood components that were reactive on individual testing was infected. In 2004, prospective testing of individual donations in regions that yielded donations that were reactive on minipool testing resulted in a 32 percent incremental yield of units with a low level of viremia that would have been missed by minipool testing.

CONCLUSIONS

Although nucleic acid amplification testing of minipools of blood donations prevented hundreds of cases of West Nile virus infection in 2003, it failed to detect units with a low level of viremia, some of which were antibody-negative and infectious. These data support the use of targeted nucleic acid amplification testing of individual donations in high-prevalence regions, a strategy that was implemented successfully in 2004.

The rights of blood recipients should supersede any asserted rights of blood donors

Some gay men have argued that the laboratory testing of blood is so accurate that continued deferrals based upon sexual activity are unnecessary and unjust. They also assert that they have a right to donate blood. There has been much debate over altering the rule barring donation from men who have had sex with other men since 1977, with blood organizations disagreeing over the best course of action. Two studies have indicated that changing the rule would increase the risk of human immunodeficiency virus (HIV) transmission. This dilemma is part of a broader issue, namely: what are the responsibilities of blood services to blood donors and recipients? Blood services should base decisions regarding donor suitability on science rather than on their donors' desires. Blood services must recognize that the rights of blood recipients should supersede any asserted rights of blood donors.

Prevalence of hepatitis C infection in a population of asymptomatic people in a checkup unit in Mexico city

Hepatitis C virus (HCV) infection has an estimated prevalence of 3% around the world. Unfortunately, many persons with HCV infection are asymptomatic. The aim of this study was to determine the prevalence of hepatitis C Virus infection in asymptomatic persons. This study was carried out in a population-based cross-sectional study in the Checkup Unit of University Hospital in Mexico City. Patients with two or more HCV risk factors were studied. Serum specimens from all patients were screened for HCV RNA by qualitative polymerase chain reaction (PCR). HCV RNA-positive serum was also screened by quantitative PCR and for HCV genotype. Three hundred asymptomatic people were included, 194 men and 106 women, with a mean age of 46.8+/-11.9. Six (2%) of the 300 people were positive and viremic. The most common risk factors in positive patients were manicures or pedicures with a nonpersonal instrument and more than three sexual partners. We concluded that hepatitis C is frequent in asymptomatic people, and those people are often viremic. In addition, this study suggests that the spectrum of liver disease in asymptomatic and newly diagnosed HCV-positive persons is broad.