Has the frequency of ABO RhD blood groups in Australian blood donors changed as a result of the removal of the variant Creutzfeldt–Jakob disease‐based deferral?

Until 25 July 2022, Australians who had spent more than 6 months in the United Kingdom or territories between 1980 and 1996 were deferred from blood donation due to the risk of variant Creutzfeldt–Jakob disease. Removal of this geography‐based donor deferral on RhD‐negative blood availability has not been reported.


Highlights
• Removal of the UK donor deferral policy increased the number of available donors with RhD-negative blood.
• The overall prevalence of blood groups within Australia remained consistent with previous findings.
• UK donors were more likely to be older and female compared with the Australian population.

INTRODUCTION
Before 25 July 2022, individuals who had resided in the UK or its territories for a total of 6 months between 1 January 1980 and 31 December 1996 were ineligible to donate blood in Australia due to the potential transmission risk of variant Creutzfeldt-Jakob disease (vCJD) [1,2].Re-evaluation of this geographically based deferral and regulatory approval for it to be discontinued was supported by risk modelling, which indicated that cessation of this deferral would result in negligible risk for vCJD transmission following blood transfusion [1].
The removal of this geographically based deferral was one of the largest recent changes to blood donation eligibility criteria within Australia where the effect on blood collections parameters could be directly attributed.It was estimated that over 737,000 people in Australia would become eligible to donate blood if this restriction was to be removed with the prediction of approximately 58,000 extra donations annually [1].However, during the first 6 months after lifting this restriction, nearly 68,000 successful donations were made, significantly exceeding estimates.This response from UK donors has had a substantial positive impact on blood collections within Australia, particularly since there is an ever-increasing demand on blood and blood products [2].
Until recently, the national prevalence of each ABO RhD group within Australia had not been reported [3].This study indicated that prevalence of B RhD-positive and AB RhD-positive individuals had increased within the community [3].The demand for O RhD-negative blood in Australia is approximately 16% of all issued red blood cell (RBC) units annually, although only 6.5% of the Australian community can provide this type [3,4].Because ABO RhD groups are inherited, their prevalence can differ across countries, with RhD-negative blood groups being more commonly found in people with European heritage [5].Therefore, the current study aimed to determine whether the removal of the UK donor deferral has influenced the availability of RhD-negative blood groups within the Australian blood donor panel.

MATERIALS AND METHODS
The study was reviewed and approved by the Australian Red Cross  UK donors may be first-time donors for Lifeblood but may also be lapsed or returning donors who may have donated blood with Lifeblood before going to the affected geographical areas for a 6-month period.'First-time' donors are defined as donating blood for the first time with Lifeblood and may or may not have been affected by the geographical deferral.Data for first-time donors as well as identified UK donors are reported since first-time donors broadly represent the community, as previously described [3].Therapeutic (hereditary haemochromatosis) donors were included in the analysis even though they were not required to complete Section A of the questionnaire.Donor's country of birth is included in the analysis where available.This is part of the routine questionnaire for first-time blood donors but cannot be directly linked to the donor's heritage.Data on ethnicity are not routinely collected during the blood donation procedure but can be self-reported in the Lifeblood profile app (Donate Blood), with up to two defined categories.

Blood donor identification and analysis
For this study, country names were matched to those that are recognized by the United Nations, and all territories were classified under the sovereign country category [6].Country of birth was further classified into regions based on Nations Online [7].Comparisons of reported donors' country of birth within the general Australian community are based on the latest estimates provided from the Australian Bureau of Statistics 2021 data cube [8].Each country classification for each region is provided in Hirani et al. [9].
All statistical analyses were performed using IBM SPSS version 23 and GraphPad Prism v8.4.3.Descriptive statistics, including the frequencies, are reported with chi-squared and one-way analysis of variance tests conducted to compare some metrics, with a p value of <0.05 considered to be significant.

DISCUSSION
Removal of the UK donor deferral in Australia resulted in a response in blood donations that exceeded the modelled predictions [1,2].The impact of removing the UK deferral has been a boost to the blood supply that has supported blood sufficiency during periods of high demand as a result of the coronavirus disease 2019 (COVID-19) pandemic.Compared with other countries, the effect of this deferral removal may have a greater influence in Australia since there is a higher rate of UK immigration and also a large number of citizens living and working in the UK for extended periods.
Following the deferral removal, UK donors provided 7.6% of all collections in the study period, with 8.2% of these being whole blood collections, despite consisting of only 6.1% of the total Australian blood donor cohort.Demand for O RhD-negative blood in Australia remains consistently high around 16% of all issued RBC units.Since RhDnegative blood groups are more commonly found in people of European heritage, it was expected that with the removal of the UK deferral that the ability to collect RhD-negative blood might be positively affected.
We found that UK donors, whether first-time or returning lapsed donors, were more likely to be older and RhD-negative and had indicated that their country of birth was either Europe or Australia/New Zealand.However, first-time donors remained more likely to be younger and RhD-positive; therefore, the total donor panel remained at 19% RhD-negative prevalence, which is similar to previous findings from before the UK deferral was removed [3].Although the overall donor panel has increased in size, the potential for blood group provision remains similar to all previous reported Australian estimates, especially since blood group prevalence in blood donors is subject to selection bias based on clinical demand, such as O RhD-negative for RBC units and group AB blood for plasma, thus resulting in preferential recruitment of donors with these blood groups.Prevalence of other clinically significant blood groups may also have altered based on UK donor deferral being lifted [9].However when compared with Australian Bureau of Statistics on country of birth, the removal of the UK donor deferral is unlikely to change the overall donor panel phenotypes drastically [9].previous estimates.This data provides further information for evidence-based forecasting of supply and could be used to support removal of this deferral in other countries.

Lifeblood
Human Research Ethics Committee (2023#29-LNR) and was conducted in accordance with the National Health and Medical Research Council's National Statement on Ethical Conduct in Human Research (2007).
Blood donor data from between 25 July 2022 to 25 July 2023 were extracted from the National Blood Management System administered by Australian Red Cross Lifeblood (Lifeblood).Donors affected by the change in the deferral policy, referred to as UK donors, were identified by extraction of the answer 'Yes' to the following screening question used in section A of Lifeblood's electronic donor questionnaire-From 1 January 1980 through to 31 December 1996 inclusive, have you spent (visited or lived) a total time which adds up to 6 months or more in England, Scotland, Wales, Northern Ireland, the Channel Islands, the Isle of Man or the Falkland Islands?For the study period, UK donors could only be identified from 25 July 2022 to 11 February 2023, after which the question was removed from the donor questionnaire.
Only blood donors with a valid ABO RhD blood type recorded on the date of data extraction (15 November 2023) were included in this analysis, and to avoid duplicate records, only the first blood group result recorded for the study period were included.Forward and reverse ABO group and RhD status is determined for each blood donation from a dedicated 6 mL BD Vacutainer ® K2 Ethylenediaminetetraacetic acid (EDTA) Crossmatch Tube (catalogue number 367941, Becton, Dickinson and Company Franklin Lakes, NJ) using the NEO blood bank analyser (Immucor, Norcross GA) according to Lifeblood's standard operating procedures.People under the age of 18 years cannot donate blood in Australia nor can those over 75 years become first-time donors.There are no other age restrictions for current blood donors who fulfil the standard selection criteria.
RESULTSA total of 566,381 blood donors were included in our analysis.Of these, 114,619 were first-time blood donors; 34,560 were confirmed UK donors, of which 28,301 were first-time blood donors, and 531,821 were non-UK identifiable donors (Table1).Where the biological sex of the donor was known, 288,210 (50.9%) of the total First-time blood donors have a lower prevalence of O RhD-negative individuals (7.8%) compared with the total blood donor panel (10.7%), to UK donors (10.8%) and UK first-time donors (10.4%), but this was not significant ( p = 0.207) (Table1 Demographics and ABO RhD prevalence in all blood donors, UK donors, non-UK identifiable donors, first-time blood donors and UK first-time donors between 25 July 2022 and 25 blood donors who attended during the study period who had a valid ABO RhD result recoded were included.Some UK donors may have attended but may not have been eligible to donate or may not have had venipuncture performed.
groups in the total Australian blood donor panel remained similar to BLOOD GROUPS AFTER REMOVING UK DONOR DEFERRAL T A B L E 1 a Only data from b Data obtained from Hirani et al. [3].