Informed consent for blood transfusion: should the possibility of prion risk be included?

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Abstract

The emergence of bovine spongiform encephalopathy (BSE) in British cattle has received significant media attention since its discovery in 1986. Transmission of this prion from cattle to humans has been documented, and the BSE prion is believed to be the causative agent for variant Creutzfeldt-Jakob disease (vCJD). Evidence of this spread is a significant threat to public health, and, although there has never been a proven case, there is a theoretical risk of transmission between humans by blood transfusions. In addition, recent animal studies have documented spread in this fashion, raising the question of whether vCJD should be included as part of informed consent for blood transfusions. The process of informed consent requires disclosure of material risks, defined as the risks that a reasonable person, under such circumstances, would want to know. Consent should, therefore, include the risks of a transfusion reaction, as well as the known infectious risks of blood. It should also include the unknown or theoretical risks of blood transfusions because full disclosure of even remote risks preserves the patient/physician trust relationship, which if breached, is very difficult to mend. Given the high level of public awareness, the potential lethality of the infection, and the theoretical risk of transmission by blood, vCJD can be considered a material risk, and consequently, it is reasonable to include it in the informed consent process.

Section snippets

Background

Classic Creutzfeldt-Jakob disease (cCJD) is a rapidly progressive, untreatable, and fatal neurodegenerative disease. It is caused by an infectious protein known as a prion. Prions are the only infectious agent devoid of nucleic acid, and they reproduce by recruiting normal cellular prion protein (PrPc) and stimulating its conversion into the disease causing isoform (PrPSc). This results in a conformational change of the protein making it resistant to proteolysis, causing amyloid deposition.1 In

cCJD versus vCJD and transmission by blood

An important distinction needs to be made between cCJD and vCJD. cCJD can be acquired, inherited, or sporadic. Sporadic cCJD occurs randomly in all countries with an incidence of approximately 1 case per million people per year.2 Acquired cCJD is from exposure to human prions through medical or surgical procedures. Transmission has been documented after neurosurgical procedures, cornea transplantation, and parenteral injection of hormones derived from cadavers.5 There have been no reported

Disclosure, therapeutic privilege, and informed consent

The concept of consent stems from the ethical principle of respect for patient autonomy and the need to involve patients in making decisions for their own health care. Canadian courts have determined that treating patients without their consent constitutes battery.16 If inadequate information is supplied to patients, this constitutes negligence.17 Beyond physician protection from litigation, consent improves patient satisfaction and reduces negative feelings and anxiety18 and should be obtained

Informed consent for blood transfusions

There are multiple components to the informed consent process. Firstly, patients should be made aware of why the transfusion is needed. Understanding this allows them to weigh the risks and benefits of the transfusion. Secondly, patients should be informed of the alternatives that are available and the risks and benefits of each of these options. Included in this process would be the option to refuse blood products. These steps lay the groundwork necessary to discuss the risks of a blood

Conclusions

cCJD and vCJD are fatal neurologic diseases that cannot be detected by screening the blood supply. The classic form of the disease is very unlikely to enter the circulation, and epidemiologic data have never shown a case of transmission through blood transfusion. However, the properties of the vCJD are quite different from cCJD, and it should not be assumed to have the same risks of transmission. Because vCJD is a relatively new infectious agent, complete epidemiologic data are not available

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