Indeterminate results in blood donor testing: what you don't know can hurt you

Improved detection of hepatitis C virus-positive blood donors and determination of infection status

BACKGROUND

In low-risk populations, variability in the sensitivity of current serological tests for Hepatitis C virus (HCV) blood donor screening may lead to the presence of false-positive results. This contributes to the unnecessary loss of blood donor samples as well as to difficulty in accurate donor counselling. The present study determined the optimal cut-off value of a chemiluminescent immunoassay for identification of HCV-reactive blood donors.

STUDY DESIGN AND METHODS

In a retrospective cross-sectional analysis of 193 973 blood donations, 578 samples that were positive for HCV antibody in a chemiluminescent immunoassay and/or RNA screening tests were identified. Blood from 379 of these positive samples was available for retesting by a second confirmatory HCV immunoassay followed by a receiver operating characteristic (ROC) curve analysis. Donors were also recalled for a new analysis.

RESULTS

Only 71 (18.7%) blood samples remained HCV-positive upon retesting, while 233 (61.5%) now tested negative and 75 (19.8%) yielding indeterminate results. A signal to cutoff ratio ≥4.32 was determined as the best differential threshold between a positive and negative result, increasing the positive predictive value from 27.3% to 66.7%.

CONCLUSION

Using a higher threshold for an HCV-positive blood sample enhances the chemiluminescent immunoassay screening test´s accuracy and helps to improve donor counselling and notification processes.

Donor notification of permanent deferral: a qualitative study on the perceptions and practices of notifier and blood donor in Mexico

BACKGROUND

Informing about permanent deferral requires a process that links the notifier with the donor in a particular way. Little is known about the type of information and how it is disclosed to the donors. The current study aimed to examine perceptions and practices of notifier and blood donor within the framework of the notification process of permanent deferral and from the perspective of the notifier-blood donor relationship.

METHODS

A qualitative study with in-depth interviews. The participants were 13 notifiers and 25 permanently deferred donors. Participants were recruited from a national blood bank and a state's blood bank. The entire dataset/narratives were analysed using the method of thematic analysis.

RESULTS

The disclosure of permanent deferral was understood as a matter of disclosing the serological test results and their medical meaning along with a concise explanation of the deferral status with regard to future blood donation and the plan to be followed. The notifiers preferred to act in accordance with the standard protocol despite acknowledging the adverse psychological and social effects to which donors are exposed when they are informed of the possible disease and the consequent permanent deferral. Donors described a variety of psychological and social affectations. They valued honesty in the communication, the clarity of the information provided and a greater involvement of the notifier.

CONCLUSION

Even though the notification process does not imply that medical care is being offered to donors, the notifier is the administrator of the well-being of the donor. Notification must not be considered as something apart from care, since it is intimately related to the health of each of the donors and their medical care.

Qualification of the Geenius HIV 1/2 supplemental assay for use in the HIV blood donation screening algorithm

BACKGROUND

A single, simplified approach for human immunodeficiency virus (HIV)-1/HIV-2 antibody confirmation/differentiation is needed for the HIV blood donation supplemental algorithm used in the United States. A clinical evaluation of the Geenius assay was performed-the same assay used for HIV diagnostic confirmation/differentiation in the United States since 2014.

STUDY DESIGN AND METHODS

Well-characterized unlinked donation samples classified as HIV negative, false positive, or confirmed positive were included in the study: 200 antibody-nonreactive, 200 HIV-1 immunofluorescence assay (IFA) confirmed-positive, and 100 antibody-screen false-positive donations, equally divided between serum and plasma. Samples were retrieved from a repository, relabeled, and tested by an immunochromatographic test (Geenius HIV 1/2 Supplemental Assay, Bio-Rad). Comparator testing involved parallel US Food and Drug Administration (FDA)-licensed HIV-1 IFA or HIV-2 enzyme immunoassay (EIA) supplemental testing for any sample missing those results as part of routine testing (otherwise test-of-record results were used). Samples with discordant results were further tested with a rapid test (Multispot HIV-1/HIV-2 Rapid Test, Bio-Rad) to provide final sample interpretations. Testing volume reductions with the Geenius were estimated from screening performed by the American Red Cross from September 2016 to April 2019.

RESULTS

Clinical results were 100% sensitivity and specificity with an indeterminate rate of 4.0% to 5.0%. From 2016 to 2019, sole use of the Geenius would reduce testing complexity for 5265 antibody repeat-reactive donations including 95.7% (5028) false positives, eliminating approximately 5000 unnecessary tests.

CONCLUSION

Geenius FDA licensure (August 26, 2019) adding the HIV-1/HIV-2 differentiation/confirmation donation supplemental claim will enable replacement of previously used FDA-licensed supplemental assays while maintaining comparable sensitivity, avoiding thousands of unnecessary HIV-1-IFA, western blot, and HIV-2-EIA tests.

Prevalence of HIV Indeterminate Western Blot Tests and Follow-up of HIV Antibody Sero-Conversion in Southeastern China

HIV-indeterminate Western blotting (WB) results are typically obtained in WB confirmatory assays, and the number of indeterminate samples may increase with the detection of HIV infections, which will present considerable challenges for the management of HIV/AIDS. Nucleic acid detection has been used as a laboratory test for screening suspected or indeterminate samples. However, the effectiveness of these assays for the differential diagnosis of HIV-indeterminate WB samples remained undetermined. In this study, 210 subjects with HIV-indeterminate WB results were detected from 6360 positive HIV screening samples between 2015 and 2016 in southeastern China, in which HIV-indeterminate WB results accounted for 3.30%. The highest proportion of indeterminate results was observed in pregnant and lying-in women receiving physical examinations (16.67%), followed by that in voluntary blood donors (8.82%). The most common WB band patterns were p24, gp160 and p24, and gp160. The follow-up study revealed that the highest negative and positive conversion rates of HIV antibodies were in samples with a single p24 band (80.28%), and with gp160 and p24 bands (86.21%), respectively. Among the Env, Gag, and Pol antibodies, samples with a Gag band showed the highest negative conversion rate (81.25%), whereas the highest positive conversion rate was observed in samples with an Env band (56.76%). In addition, quantitative and qualitative HIV nucleic acid testing exhibited the highest sensitivity (96.3%) and specificity (97.85%), respectively. Our results indicate a lower proportion of HIV indeterminate WB results in southeastern China compared to previous reports, and the follow-up re-examination of patients with HIV indeterminate results should be performed. Nucleic acid testing facilitates the identification of HIV infections.

Anti-HCV immunoblot indeterminate results in blood donors: non-specific reactivity or past exposure to HCV?

BACKGROUND AND OBJECTIVE

The significance of anti-HCV immunoblot (IB) indeterminate results can be difficult to determine. We analysed results for blood donors tested on the MP Diagnostics HCV Blot 3.0 IB assay to determine whether indeterminate results representing past exposure to HCV could be distinguished from those due to non-specific reactivity.

MATERIALS AND METHODS

Results for all donors tested by IB during the study period (July 2010 to December 2013) were included in this study.

RESULTS

Of 131 donors tested by IB, 34 (26.0%) were negative, 38 (29.0%) were indeterminate, and 59 (45.0%) were positive. There was no significant difference in IB band reactivity strength between indeterminate and positive donors. The PRISM HCV chemiluminescent immunoassay (ChLIA) sample to cut-off (s/co) ratio distribution for the indeterminate donors was significantly higher than for those with biological false reactivity (P = 0·037), but significantly lower than for donors who were IB positive/HCV RNA negative (P < 0·001) or IB not tested/HCV RNA positive (P < 0·001). Of donors available for follow-up, 53.1% of the indeterminate group disclosed a putative risk factor for HCV infection compared to 39.4% (P < 0·001) for the IB-negative group, 76.6% (P = 0·065) for the IB-positive group and 83.4% (P < 0·001) for the HCV RNA-positive group.

CONCLUSION

The results of this study indicate that PRISM ChLIA s/co ratios >2·00 with IB indeterminate results predict exposure to HCV, particularly in the presence of putative risk factors for HCV infection. These findings may be applied to optimizing counselling of donors with indeterminate HCV results.

Risk factors for retrovirus and hepatitis virus infections in accepted blood donors

BACKGROUND

Risk factor surveillance among infected blood donors provides information on the effectiveness of eligibility assessment and is critical for reducing risk of transfusion-transmitted infection.

STUDY DESIGN AND METHODS

American Red Cross, Blood Systems, Inc., New York Blood Center, and OneBlood participated in a case-control study from 2010 to 2013. Donors with serologic and nucleic acid testing (NAT) or NAT-only confirmed human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), or serology-confirmed human T-lymphotropic virus (HTLV) infections (cases) and donors with false-positive results (controls) were interviewed for putative behavioral and demographic risks. Frequencies and adjusted odds ratios (AORs) from multivariable logistic regression analyses for each exposure in cases compared to controls are reported.

RESULTS

In the study, 196 HIV, 292 HBV, 316 HCV, and 198 HTLV cases, and 1587 controls were interviewed. For HIV, sex with an HIV+ person (AOR, 132; 95% confidence interval [CI], 27-650) and male-male sex (AOR, 62; 95% CI, 27-140) were primary risk factors. For HBV, first-time donor status (AOR, 16; 95% CI, 10-27), sex with an injection drug user (IDU; AOR, 11; 95% CI, 5-28), and black race (AOR, 11; 95% CI, 6-19) were primary. For HCV, IDU (AOR, 42; 95% CI, 13-136), first time (AOR, 18; 95% CI, 10-30), and a family member with hepatitis (AOR, 15; 95% CI, 6-40) were primary. For HTLV, sex with an IDU (AOR, 22; 95% CI, 10-48), 55 years old or more (AOR, 21; 95% CI, 8-52], and first time (AOR, 15; 95% CI, 9-24) were primary.

CONCLUSIONS

Despite education efforts and risk screening, individuals with deferrable risks still donate; they may fail to understand or ignore or do not believe they have risk. Recipients have potential transfusion-transmitted infection risk because of nondisclosure by donors.

Understanding the meaning of permanent deferral for blood donors

BACKGROUND

To ensure the safety of the blood supply, it is necessary to permanently defer blood donors with a repeat-reactive transmissible disease test result. The purpose of this study was to explore the permanent deferral experience from the donor's perspective.

STUDY DESIGN AND METHODS

A qualitative study was conducted with donors from two Canadian blood centers who received written notice of permanent deferral in six deferral categories: human immunodeficiency virus-1 and/or -2 and hepatitis C virus and/or hepatitis B virus (negative, indeterminate, or positive). Telephone interviews were conducted with a semistructured questionnaire. Interview transcripts were coded and central themes were identified. The data were then modeled to illustrate the relationships between the themes.

RESULTS

Twenty-eight permanently deferred donors were interviewed and described a variety of negative emotional and behavioral responses including confusion, shock, disbelief, panic, fear, anger, stigmatization, and loss. A conceptual model was developed illustrating the phases that a deferred donor goes through (identifying as a healthy donor, receiving notification, experiencing emotional and behavioral reactions, trying to make sense of what happened, and taking action) as they travel along the path to becoming either a "reconciled" or "not reconciled" permanently deferred donor. Participants offered constructive suggestions for modifying the notification process including revising the letter, providing follow-up, and educating family physicians.

CONCLUSIONS

To our knowledge, this is the first study to use qualitative research methodology to explore the experience of permanent blood donor deferral. More studies are needed to validate and expand this preliminary conceptual model.

Current risks of transfusion-transmitted agents: a review

CONTEXT

Infectious disease testing has dramatically improved the safety of blood for transfusion in the United States, especially since the introduction in 1999 of nucleic acid amplification testing. In 2004, methods (primarily culturing) for detecting bacteria in platelets were also added.

OBJECTIVE

To provide current risk estimates for the likelihood of viral transmission by test-negative blood components and to illustrate the safety improvements since the introduction of bacterial testing of platelets.

DATA SOURCES

Published literature from 1999 through 2006 and unpublished American Red Cross data sources.

CONCLUSIONS

The risk of human immunodeficiency virus and hepatitis C virus transmission through blood transfusion since the introduction of nucleic acid amplification testing is approximately 1 in 2 million. Hepatitis B virus risk, for which nucleic acid amplification testing is not performed routinely, remains at 1 in 200,000 to 500,000 using a combination of anti-hepatitis B core and hepatitis B surface antigen testing. Seven cases of transfusion-transmitted West Nile virus have been reported since the introduction of nucleic acid amplification testing in 2003, but none has been reported since system-wide implementation of processes to increase the test sensitivity for use in epidemic areas. The residual risk of receiving a bacterially contaminated platelet component with clinical consequences is estimated at approximately 1 in 75,000, if culture negative and 1 in 33,000 if not tested by culture methods.

Integration of nucleic acid amplification test results into hepatitis C virus supplemental serologic testing algorithms: implications for donor counseling and revision of existing algorithms

BACKGROUND

The routine use of hepatitis C virus (HCV) nucleic acid amplification testing (NAT) donor screening assays has provided an opportunity for revision of the current HCV supplemental testing algorithm, which requires that recombinant immunoblot assay (RIBA) be performed on every HCV enzyme immunoassay (EIA)-repeat-reactive donation. The FDA has approved variance requests to use a new algorithm that eliminates the need to perform RIBA when HCV NAT results are reactive. Data are provided in support of this new algorithm.

STUDY DESIGN AND METHODS

HCV EIA (including signal-to-cutoff optical density ratio), RIBA, and NAT data were compiled from 33.2 million donations screened over an approximately 4-year period by the American Red Cross and Blood Systems Laboratories. Further, donations having specific combinations of HCV EIA, RIBA, and minipool (MP) NAT results were evaluated, with more sensitive individual-donation (ID) NAT, to construct improved counseling messages for donors.

RESULTS

Of 47,041 EIA-repeat-reactive donations, 49.3 percent were RIBA-positive, 17.1 percent RIBA-indeterminate, and 33.5 percent RIBA-negative. NAT-reactive rates were 79.2, 2.5, and 0.18 percent for RIBA-positive, -indeterminate, and -negative donations, respectively. The new algorithm classified an additional 1 percent of donations as HCV-infected while at the same time detecting all infections classified as HCV-infected under the current algorithm. An additional 2.4 percent of RIBA-positive, MP NAT-nonreactive donations were reactive when a frozen-thawed aliquot was retested by ID NAT.

CONCLUSION

Integrating HCV NAT results with RIBA results for purposes of donor notification allows more appropriate counseling messages to be given to EIA-repeat-reactive donors. The new HCV supplemental algorithm is an acceptable alternative to the current algorithm because it provides equivalent or superior accuracy in formulating donor counseling messages and may also result in reduced costs and more timely notification of infected donors.

Can we improve the management of blood donors with nonspecific reactivity in viral screening and confirmatory assays?

Donors with nonspecific reactivity in viral screening or confirmatory assays are problematic for blood services because of donor management issues and product loss. Considerable experience has now accumulated in the use of screening and confirmatory assays; therefore, it is timely to examine the ways in which donors with nonspecific reactivity are managed. In this review, we summarize the causes and characteristics of nonspecific reactivity in blood donors and approaches for reducing the number of nonspecific reactive results and we offer some suggestions for improving the management of these donors.

The donor notification process from the donor's perspective

BACKGROUND

Despite large numbers of blood donors being notified of abnormal infectious disease screening results, there has been little scientific study of the effects of this process.

STUDY DESIGN AND METHODS

With a 28-item questionnaire, an anonymous mail survey was conducted of 4141 blood donors notified of 15 distinct categories of abnormal infectious disease screening and confirmatory test results.

RESULTS

The survey had a 42 percent response rate, and 10 percent of the respondents did not recall being notified of their results. Of the 1556 respondents who recalled being notified, 27 percent contacted the blood center for further information, 60 percent discussed their results with a health care provider, and 73 percent of permanently or indefinitely deferred donors correctly understood their deferral status. Confusion and emotional upset were reported in 81 and 75 percent of notified donors, respectively.

CONCLUSIONS

The notification process appears to achieve most of its aims in the majority of donors. Nevertheless, some donors did not understand that they were ineligible for future donation, and many donors were confused and upset. These data indicate that the adverse impact of notifying donors about abnormal test results needs to be considered when new blood donor screening tests and confirmatory algorithms are being licensed and implemented. Further studies of the effectiveness of newer revised donor notification materials are needed.

Analysis of voluntary blood donors with biologic false reactivity on chemiluminescent immunoassays and implications for donor management

BACKGROUND

Biologic false-reactive (BFR) results in blood donors are problematic due to both component loss and donor-management issues. This report analyzes the results of a longitudinal study of BFR donors and the implications for donor management.

STUDY DESIGN AND METHODS

Donors who gave BFR results on HBsAg, HIV-1/HIV-2, HCV, or HTLV-I/HTLV/II chemiluminescent immunoassays (ChLIAs) (PRISM, Abbott) between May 1997 to March 1999 were analyzed. Donors were followed up for up to three donations after an index BFR episode. In addition, results of any negative donations before the index BFR result but within the study period were included in the analysis.

RESULTS

For donors who gave an index BFR result on the HBsAg ChLIA, 14.3 percent remained BFR at subsequent donations, whereas for the anti-HIV-1/HIV-2, anti-HCV, and anti-HTLV-I/HTLV-II ChLIAs, the figures were 66.0, 77.4, and 71.6 percent, respectively. For donors who gave a second BFR result, the percentage who remained BFR at subsequent donations was 75.0, 80.6, 84.6, and 74.5 percent for the four assays, respectively. The rate at which negative repeat donors became BFR during the study period was 0.02, 0.07, 0.12, and 0.02 percent for the HBsAg, anti-HIV-1/HIV-2, anti-HCV, and anti-HTLV-I/HTLV-II assays, respectively.

CONCLUSIONS

Our results indicate that donors who give an index BFR result on the ChLIAs (PRISM, Abbott) should be allowed to continue donating because most donors with a HBsAg BFR result were negative at subsequent donations, and between 22.6 and 34.0 percent of those with BFR results on the HIV-1/HIV-2, HCV, or HTLV-I/HTLV-II assays gave subsequent negative donations. However, donors who give a second BFR result should be counseled and deferred because they were very unlikely to give subsequent negative results.

Improved efficiency of national HIV, HCV, and HTLV antibody testing algorithms based on sequential screening immunoassays

BACKGROUND

Traditional strategies for clarifying the antibody status of donors giving repeatedly reactive (RR) results on primary screening immunoassays (IA1) have usually involved direct testing by immunoblot. However, such strategies can generate nonspecific in determinate results. The aim of this report is to present the results of an alternative strategy based on the use of sequential immunoassays (SI) before immunoblot testing.

STUDY DESIGN AND METHODS

The efficiency of traditional and SI strategies was compared in terms of the number of IA1 RR samples requiring immunoblot testing and the percentage of immunoblot tests giving indeterminate results. In addition, the biologic false- reactive overlap between the PRISM assays selected as IA1 and candidate secondary screening immuno- assays (IA2) was calculated to determine the most efficient IA1/IA2 combinations.

RESULTS

There was a significant decrease in the proportion of IA1 RR samples requiring immunoblot testing under the SI strategy when compared with existing site-specific strategies for HIV (0.49 vs. 0.08, p < 0.05), HCV (0.85 vs. 0.42, p < 0.05), and HTLV (0.69 vs. 0.05, p < 0.05) algorithms. In addition, there was a significant decrease in the percentage of immunoblot tests giving indeterminate results for HIV and HTLV under the SI strategy. However, there was no significant difference in the proportion of confirmed positive results for HIV, HCV, or HTLV before and after national SI algorithm implementation. For the anti-HIV IA2s, there was considerable variation of biologic false-reactive overlap with the PRISM HIV O plus chemiluminescent immunoassay (range, 1.6-15.6%).

CONCLUSIONS

The results presented in this report demonstrate that the sequential use of screening immunoassays before immunoblot testing can significantly reduce both the number of immunoblot tests and proportion of indeterminate results, without impacting sensitivity, thereby improving algorithm efficiency and simplifying donor management.

Impact of changes in viral marker screening assays

BACKGROUND

Monitoring the performance of routinely used infectious disease serologic tests is necessary to evaluate their effectiveness in identifying true-positive units and erroneously disqualifying safe blood donors.

METHODS

With two large screening test data sets collected between 1991 and 1998 and between 1997 and 2000, the impact of changes in screening assays for HIV, HCV, and HBsAg was analyzed with regard to the prevalence of confirmed-positive, indeterminate, and confirmed-negative results and the deferral of donors with an indeterminate or negative results (donor loss).

RESULTS

The prevalence of indeterminate results and donors loss increased significantly in the 6 months after introduction of an HIV-1/2 EIA. A second-generation HCV EIA increased the detection of confirmed-positive donations in repeat donors (p < 0.001) and increased the prevalence of indeterminate donations. Implementation of a third-generation HCV EIA resulted in a significant decrease in indeterminate results in first-time donors. Nonspecific test results increased when HBsAg test kits from a different manufacturer were introduced or different lots of HIV antibody screening test kits from the same manufacturer were used.

CONCLUSION

Introduction of newly licensed versions of assays, switching kit manufacturers, and lot-to-lot variations have an impact on rates of deferrals of safe donors as well as sensitivity of routine screening. Before considering changes in screening tests, blood centers should be aware of, and evaluate, the potential impact on donor loss.

Advances in pretransfusion infectious disease testing: ensuring the safety of transfusion therapy

The public expects a zero-tolerance policy for the transmission of infectious agents by blood transfusion. Although unrealistic, the efforts to reach this goal have produced an extremely safe albeit costly blood supply [82]. Blood collecting agencies, the FDA, physicians, and scientists have over the past 20 years created a complex system of layers of protection to interdict transfusion-transmitted infections (Fig. 2). As new, exotic, potentially blood transmittable infectious agents evolve [83], new barriers will be erected to [figure: see text] interdict these agents. In the interim, the US blood supply is the safest in the world.