ALGORITHM TO USE HEPATITIS CORE ANTIBODY AND/OR ID-NAT FOR HBV SCREENING

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1 ALGORITHM TO USE HEPATITIS CORE ANTIBODY AND/OR ID-NAT FOR HBV SCREENING Authors Ranjay Kumar Choudhary Research Scholar, Faculty of Applied Science, Manav Rachna International University, Faridabad, Haryana,India Dr. Pratibha Singh Assistant professor, Faculty of Applied Science, Manav Rachna International University, Faridabad, Haryana,India Prof. (Dr.) Jaswant Singh Head, Biomedical Engineering Manav Rachna International University, Faridabad, Haryana, India Dr. Harprit Singh Consultant & In charge, Transfusion Medicine, Alchemist Institute of Medical Sciences, Gurgaon, Haryana,India. Keywords: HBV, NAT, Core, protocol, blood donor, cost effectiveness, algorithm, HBsAg, blood safety, blood screening. Abstract: Aim: To develop algorithm focussed on increasing the availability of blood components & cost effectiveness, without compromising blood safety, in a setup where NAT and serological methodological are available. Background: There is increasing usage of total Anti-HBV Core Antibody (anti- HBcAb) & NAT screening for the HBV screening among blood donors. This requires additional resource mobilisation, which is limited in developing countries and increases the blood discarding. Therefore, such algorithm is especially helpful when voluntary blood donors are insufficient

2 to meet the required blood requirements and resources are limited for blood screening as in developing countries. Methods: Screening reports were evaluated for HBV by immunoassay (HBsAg & Anti- HBcAb) and NAT. Initial reactive samples were confirmed by discriminatory HBV assay. Results: All samples reactive by immunoassay were also reactive by NAT. On the contrary, no sample was observed, which was NAT reactive and is immunoassay non reactive. There is 12.8% and 88% reduction in the direct cost of blood screening and wastage. Conclusion: Risk of post transfusion hepatitis (PTH) has declined to current HBV transmission risk of 1/280,000 to1/357,000 in USA (HBV NAT is not mandatory in USA). Thus, based on present study outcomes, risk of PTH and cost effectiveness, suggested protocol for NAT screening for the specific core reactive units has potential to improve the resource mobilisation and to increase availability of safe blood. HBsAg is mandatory screening test, therefore, HBsAg reactive units need not to be retested by NAT. HBsAg and Anti-HBcAb screening are essential for enhancing the blood safety. Aim & Background Hepatitis B Virus (HBV) is transmitted by blood and is considered to be a major challenge for blood safety because of associated morbidity and mortality. Transfusion-associated HBV continues to be a major problem in India, and more so in patients receiving repeated transfusions. Hepatitis B surface antigen (HBsAg) is mandatory HBV screening in India (Chaudhuri V et al., 2003).. It has been proved that, some HBsAg non reactive but anti-hb core antibody (Total; Anti-HBcAb) reactive individuals continue to replicate HBV (Yotsuyanagi H et al., 2001). Therefore, the non reactive result of HBsAg in the blood can not reflect that the person is completely free from HBV. Blood containing Anti-HBcAb with or without detectable presence of HBsAg might be infectious. In 1992, Anti-HBcAb was introduced in the screening process in USA. It is now required by USFDA as an additional screen for HBV (AABB 17th Ed). However, in India Anti-HBcAb is an optional investigation but not mandatory. Window period has been a challenging situation that has proposed threat to blood safety. Therefore, screening methods should focus on reducing window period and enhance blood safety. However, this requires increased requirement of resources. Recently, Nucleic Acid Test (NAT) is one such methodology which is gaining

3 wide acceptance in India. This test has been approved for screening of blood donors but it is not yet mandatory in India. The permutation combination of use of HBsAg (mandatory blood screening investigation), Anti-HBcAb and NAT screening (optional blood screening investigation) for HBV screening may offer a new opportunity to enhance blood safety & blood screening programmes. However, the feasibility of implementing as policy should be considered based on pathogenicity, morbidity, mortality, endemicity, ethics and available resources (since the requirements for infrastructure, financing, staffing levels, training and quality systems and the overall costs of implementation may far outweigh any potential benefit in terms of increased blood safety). The present study was carried out to study the role of anti- HBc antibody and HBV NAT in blood screening. Materials & Methods Donated blood was evaluated and collected between October 2009 and April 2011 covering 8221 samples. All samples were screened for serology and Individual Donor- NAT (ID- NAT). Serological screening was performed by Random Access Chemiluminescence Immuno Assay (CLIA) for HBV including HBsAg & HBcAb Total (IgM & IgG), (Vitros ECI; OCD; JNJ from USA). Individual donor ID-NAT was performed by Transcription Mediated Amplification (TMA) technology (Novartis Diagnostic; USA). Anti-HBcAb requires additional kit utilizing the same infrastructure for immunological screening for HBV such as ELISA or CLIA. NAT testing requires special facility and trained manpower. The indirect costing, such as space value, support services, technical cost etc., of having a NAT facility is beyond the limits of comparison because of highly variable factors. Therefore, for the costing purpose, direct cost was used, being easy to calculate and compare among blood centres. The initial reactive samples were re-tested and confirmed by the discriminatory HBV assay (Iudicone P et al., 2009). Results Of the 8221 blood donors, 581 (7%) were reactive for HBV marker (Fig. 1). All the samples screened reactive by serological markers- HBsAg & Anti-HBcAb, were compared with ID- NAT. NAT is a screening test having high false positive results, therefore confirmatory testing was performed, which showed 42 samples to be positive for HBV DNA (Figure 2). Of all the samples reactive for HBV, 7.2% is reactive by discriminatory HBV assay (Figure 1 &

4 2). About 2.5% of solitary HBcAb reactive samples were positive by ID-NAT. However, no non- reactive sample was observed to be reactive by ID-NAT, during the study period. Total cost reduction was observed to be in tune of 12.8% (Table 1) with the proposed protocol of screening blood for HBV (Figure 3). Conclusion Post Transfusion Hepatitis (PTH) is a major concern of blood safety. Although, incidence of PTH has declined significantly, but the management of PTH still remains an expensive affair. The cost of each life- year gained was $9010, that is nearly 20.5 times that of each Quality Adjusted Life Years (QALY) gained ($5769), which is 13.1 times the annual per capita Gross National Product (GNP) of the Indian population (Aggarwal et al., 2002). In developing countries such as India, marginal cost effectiveness and cost utility of therapy were compared adversely with annual per capita income. Therefore, HBV screening remains an essential investigation to enhance the blood safety across the globe. All the units found to be reactive by ID-NAT were also reactive by immunoassay. However, there is always a possibility that immunoassays may miss out HBV harbouring unit (false negative) and should be picked up by NAT. In present study, there was no sample which was NAT reactive but immunoassay nonreactive. Contributory reason for this can be an underlying fact that NAT has been developed in the countries, where more focus lies on HIV prevention, and have lower Hepatitis B prevalence (France AM et al., 2012). Although the NAT screening for HBV is available in USA for more than a decade, USFDA has not made the test mandatory yet. This is because of the fact, that there is no clear cut evidence to prove, that NAT implementation can reduce significant HBV transmission by blood transfusion (AABB 17th Ed). Studies have not been able to clearly state avoided HBV related morbidity and mortality (Velati et al., 2008). On the other hand, it has commented on theoretical increased possibility of finding NAT reactive blood donors because of immunisation (AABB 17th Ed, Stramer SL et al., 2011). HBV vaccination can be picked up by sensitive HBsAg immunoassays as well as NAT (Dow BC et al., 2002, Stramer SL et al., Presently universal HBV screening for perinatal screening and childhood HBV vaccination is being highly encouraged. Easy availability of low cost vaccination (less than $15 for the whole vaccination regime) and increasing awareness about the disease has increased HBV vaccination among self motivated people. Increased prevalence of HBV in Indian subcontinent and genetic differences, can contribute to the fact that a sample can be NAT reactive and immunoassay non reactive. Therefore, history of HBV vaccination should be reviewed while evaluating the NAT results.

5 Results of confirmatory assay showed that 7.2% of initial reactive units were truly harbouring HBV DNA (Fig. 2). The similar finding of the presence of replicating HBV among HBsAg negative and Anti-HBcAb Positive have been published earlier (Yotsuyanagi H et al.,2001 Panigrahi R et al., 2010). As Anti-HBcAb being easier to perform than NAT, Anti-HBcAb core test can t be ruled out under the present scenario. Thus, complete elimination of traditional testing methods in the near future seems to be difficult (Busch MP 2004, Stramer SL, 2005, Kleinman SH et al. 2005). Earlier observations have shown that, Anti-HBcAb screening detects HBsAg EIAnegative HBV-infected donors, at a rate comparable to the estimated residual risk for HBV window-period infections (Kleinman SH et al., 2003) NAT can contribute the strategy of safe blood along with core in specific cases where HBV core is reactive by immunoassay (Figure 3). Not only this can increase the blood safety but also decrease the wastage of blood which is in the tune of 6.24% in our study because of anti-hb core reactive status. HBsAg is a mandatory investigation for screening HBV among blood donors. Therefore, wastage because of Anti-HBcAb screening can be reduced to more than 88% (Table 1). This can be explained by low positive predictive value of anti-hb core antibody (Korelitz JJ et al., 1996). This implies, that total HBV screening related wastage, can be reduced to less than 12% from existing levels. The reduction in wastage should have significantly enhanced the availability of blood components for patients. This is of more significance in our country, where blood collection is less than the requirements. Also, direct reduction in cost by more than 12.8% itself is significant (Table 1). Increased availability and revenue per component/ unit can greatly enhance the cost effectiveness of NAT and optimal utilisation of the resources. Therefore, proposed pathway will increase the availability of blood and reduce the cost of manufacturing safe blood components. Universal use of NAT for screening of donated blood, as a policy on larger level, should be reviewed cautiously. As no screening test alone can ensure the blood safety, the pillars of blood safety measures i.e. voluntary blood donation, donor education and screening questions, still remain cornerstone. Therefore, resource mobilisation from infection screening to repeat voluntary blood donation, for enhancing the blood safety, remains an important pillar for enhancing the blood safety. The use of NAT screening is gradually being accepted in our country. Increasing number of blood centres is adopting this method for screening of blood. The method is approved under Indian legal framework (Central Drugs Standards Control Organisation), but it is not mandatory. Anti-HBcAb is in use for quite a long time.

6 However, non specific nature of Anti-HBcAb antibody has been one of main culprits of the increase in blood wastage. Based on present study outcomes and cost effectiveness, therefore suggested protocol is for NAT screening for the specific core reactive units (figure 3). HBsAg, is a mandatory screening test for blood safety, therefore, there is no need to be retested by NAT. However, the strategy should be individualized by respective organisation based on the target population and resource availability, accreditation and organisational vision and values, where healthcare sector is expected to meet the developed countries at par can think in terms of implementing the combined strategy without compromising on the blood safety. Acknowledgement Ranjay Kumar Choudhary, as a research fellow, has performed the collected the sample for study, conducted the study & helped in drafting of paper and approved final version of paper. Dr. Jaswant Singh contributed to essential regents/ tools & assistance in technical & workplace assistance. He has helped in critically reviewing the paper and approving final version of paper. Dr. Harprit Singh conceptualized and designed the study, structured & analysed the data and wrote the paper. Final revision and approval of the submitted final versions of the paper was done by Dr. Harprit Singh. Conflict of interest This research project was self sponsored without any financial aid from any institution/ company. There is no financial interest of/in any company or institution that might benefit from their publication. The authors have no competing/ conflict of interests associated with this publication.

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