Recipients of blood or blood products “at vCJD risk”
BMJ 2004; 328 doi: https://doi.org/10.1136/bmj.328.7432.118 (Published 15 January 2004) Cite this as: BMJ 2004;328:118All rapid responses
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CJD Letter
It is surprising that a statistician will list potential risks with
no attempt to quantify their likelihood. A litany of possibilities can
strike fear into the hearts of an impressionable public yet this could be
substantially ameliorated when it is shown how unlikely these risks are.
The notification statistics make it clear that there is no epidemic of
variant CJD1. As previously suggested2, it becomes ever clearer that the
variant is not new and the numbers and age distribution of cases reveal it
to be an extremely rare disease which becomes symptomatic and detected in
between ten to twenty cases each year in the United Kingdom. That being
so, even if those cases were likely to be infectious for up to five years
before detection, only around one hundred cases in total are a possible
hazard in the UK at any time.
The press release cited3 stated that 15 donations were known to have
been given by patients who later developed vCJD and that 24 million units
had been donated since 1996. This indicates that any potential recipient
has less than a one in a million chance of receiving a unit of blood from
someone who later might develop variant CJD. Whether this might be
infectious remains an open question and the case cited received blood
which had not been leuco-depleted.
The epidemiological evidence is confirming that this disease is rare
and not increasing in frequency(loc.cit.). Consequently, even if whole
blood was infectious, the risks of blood transfusion inducing variant
disease in a member of the general public are in the same ball park as his
or her chances of ever developing the disease and less than one in a
million.
Given this level of risk, there is little fear of the detection of
PrPsc positive tonsillar tissue in the prospective study and its value
must be extremely questionable. I note the declared interest of Dr Bird in
studies of detectable prion.
References:
1 Scottish Centre for Infection and Environmental Health (SCIEH)
Creutzfeldt-Jakob disease notification
statistics.www.show.scot.nhs.uk/scieh/PDF/pdf2003/50.pdf
2 George A Venters. New variant Creutzfeldt-Jakob disease: the epidemic
that never was. BMJ;2001: 858-61.
3 Department of Health. Blood transfusion incident involving
vCJD.www.info.doh.gov.uk/doh/embroadcast.nsf/vwDiscussionAll/
Competing interests:
None declared
Competing interests: No competing interests
To the editor -
Sheila Bird [1] reminds us how cautious we should be when assessing the
risk of vCJD transmission via blood products. In an NHS where patient
participation and empowerment is so often stressed, it is surprising that
patients are not offered informed consent regarding the risk of vCJD
transmission from receiving blood products. The sooner a national protocol
for vCJD counselling appears the better. Patients deserve the right to
avoid a risk however small, especially when it is acknowledged as being
unquantified, and the consequences may be so disastrous.
I would like to draw attention to the risk posed by one of many
pooled blood products, namely anti-D. The larger the number of blood
donations that make up the donor pool, the greater the potential risk of
vCJD transmission if we are to learn from past outbreaks of hepatitis C
and HIV from blood products. The routine administration of prophylactic
anti-D to rhesus negative pregnant women at 28 and 34 weeks gestation,
imposes an unquantified risk on those with a whole lifetime to incubate
vCJD. Women deserve to know anti-D is a blood product from multiple donors
posing a potential risk both to them, and their children.
1 Recipients of blood or blood products "at vCJD risk" Sheila M Bird
BMJ 2004;328:118-119, doi:10.1136/bmj.328.7432.118
Competing interests:
None declared
Competing interests: No competing interests
Fully informed
I agree the risk of transmission of vCJD via maternal anti-D is
vanishingly small. The use of plasma from the USA is significant regarding
safety, as the only case of vCJD in the USA occurred in an individual who
lived in the UK for most of their life. However Bovine Spongiform
Encephalopathy (BSE) has occurred, albeit in very limited numbers in the
USA.
Over 100,000 doses are given in the UK per year. The largest supplier
in the UK, Bio Products Laboratory (BPL), estimate that the number of
donors contributing to the donor pool for each injection, is of the order
of 150. However, even if a donor had vCJD, there is a massive dilution
effect from the original 250-500 kg of plasma in each pool to the final
injection. In experimental models the plasma fractionation used to prepare
anti-D has been shown to cause a significant log reduction in prion
proteins in spiked samples. The injection is intramuscular rather than
intravenous, and it is unlikely that maternal prion transmission occurs at
all.
There is no doubt regarding the cost-effectiveness [1] of anti-D. It
costs only £7,600 per Quality adjusted life year (QALY), for avoidance of
disability and fetal/neonatal loss taken together (Assuming fetal/neonatal
loss is associated with 10 QALYs).
Nevertheless, recipients should be informed they are receiving a
pooled blood product, and be given reassuring information at the same
time. The product literature for anti-D, which is designed for patients,
and should be given to each recipient states :
‘When medicinal products prepared from human blood or plasma are
given to patients, the risk of infectious diseases by certain germs cannot
be totally ruled out, including some which may not have been discovered.’
They then go on to describe steps that are made to reduce these
‘germs’. Only by documenting such explanations to patients can the NHS be
protected from any potential future litigation. Above all, patients should
not be pressurized into receiving such a product if they have significant
concerns over its safety. Women should also be informed when it is neither
necessary nor cost effective, for instance when they [1] :
(i) have opted to be sterilised after the birth of the baby
(ii) are in a stable relationship with the father of the child, and the
father is known or found to be RhD-negative
(iii) are certain that she will not have another child after her current
pregnancy.
The UK protocol for CJD surveillance [2] includes a Transfusion
Medicine Epidemiology Review (TMER) of any confirmed cases of vCJD. The UK
Transfusion services are informed six monthly of all definite and probable
cases of sporadic and familial CJD who were reported as blood donors
("main TMER") and those that were reported as blood product recipients. It
is relatively easy to see if cases of vCJD have been recipients of major
blood components. It is far harder to trace if they have received
fractionated products such as anti-D, or varicella zoster, tetanus,
hepatitis B and Rabies immunoglobulin. Maternal notes are only kept for 25
years making this sort of surveillance yet more difficult. Surveillance
may not be necessary in the light of a falling incidence of vCJD, wasting
significant NHS resources, but then maybe its better to waste money than
be caught unaware.
1 NICE appraisal document 41-
http://www.nice.org.uk/cat.asp?c=31679
2 UK protocol for CJD surveillance-
http://www.cjd.ed.ac.uk/PROTOCOL.HTML
Competing interests:
The Rhesus negative husband of a Rhesus negative mother.
Competing interests: No competing interests