Rapid Responses to:
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Rapid Responses: Rapid Responses published:
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Protecting a future nation.
- Stephen J Katona (30 January 2004)
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A Plea for Sanity in Assessment of Risk
- George A Venters (2 February 2004)
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Fully informed
- Stephen J Katona (2 February 2004)
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Stephen J Katona, SHO Obstetrics and Gynaecology Hereford County Hospital
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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 |
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George A Venters, retied consultant in Public Health Medicine 8 Biggar Road Edinburgh EH10 7BQ
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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 |
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Stephen J Katona, SHO Obstetrics and Gynaecology Hereford County Hospital
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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. |
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