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The Precautionary Principle. Managing theoretical risks in public health. Policy Problem. The blood system is confronted with the potential new infectious threat from vCJD Must take measures to protect against this theoretical risk - PowerPoint PPT Presentation
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The Precautionary Principle
Managing theoretical risks in public health
Policy Problem
The blood system is confronted with the potential new infectious threat from vCJD Must take measures to protect against this
theoretical risk Must balance theoretical reduction in supply
that could be caused by developing a policy
Background
CJD
Most common human TSE Due to effects of prion 4 Forms
classical familial iatrogenic variant
Classical CJD
develops in 6th to 8th decade of life
rapidly progressing dementia
cerebellar symptoms
death within 3 to 12 months
Variant CJD
Variant CJD first identified in 1996 in UK average age of onset 27 presents with behavioural symptoms invariably fatal, average duration of
symptoms of 14 months
Diagnosis/Treatment
No blood test
No treatment
Policy Challenge
vCJD and the blood supply
First theoretical infectious risk to challenge the Canadian blood system since the Krever Inquiry
UK Events Concerns soon developed that this
condition may be blood transmitted led to a UK decision to import certain
blood product requirements from other countries
Canadian officials immediately began considering whether Canada should use blood from individuals who had traveled to the UK
What information is needed to develop policy?
Risk of transmission of vCJD
Reduction in blood supply of any policy
How much reduction in the blood supply could the sytem sustain
Risk of Transmission of Classical CJD – Case control studies
Kondo, 1982 0.56 (0.06-5.56)
Harries-Jones, 1988
0.77 (0.44-1.50)
Esmonde, 1993 0.68 (0.39-1.20)
Van Dujin, 1998 0.56 (0.37-0.97)
Collins, 1999 0.89 (0.57-1.40)
Risk of Blood Transmission of vCJD
No epidemiological studies Theoretical Risk
higher prion concentration affinity for lymphoreticular system existing model for peripheral transmission
(oral)
Impact of Donor Deferral Policies
Full deferral 22% reduction
1 month deferral 10% reduction
6 month deferral 3% reduction
Sustainability of Blood Supply Reduction
Blood system had been able to sustain a 3% reduction in supply in the past
What Policy should be instituted?
Options No policy should be instituted
vCJD is a theoretical risk, there is no epidemiological evidence of harm
A partial policy should be instituted balances reducing the risk of vCJD with potential
harm caused by reducing the blood supply Full policy should be instituted
even 1 day in the UK puts you at risk
Canadian Response
Canadian blood system embarked upon risk assessment analysis
conducted a systematic evaluation of the impact on supply of a donor deferral policy versus the potential health benefit of such a policy.
Policy Decision
August 1999, policy-makers officially announced that individuals who had traveled to the UK for 6-months between the years 1980 and 1996 would be deferred from donating blood
Is this Evidence-Based Decision-Making?
Sabatier-Lomas Policy Analysis Framework
A schematic of the contextual influences on the decision-making process
Social Problem/Issue
Power Relationships
Persuasion
Epistemiology, paradigms
Information
InstitutionalStructure for
Decision-Making
ProducersResearchers
InstitutesPollsters
PurveyorsMedia
AdvocatesNetworks
Knowledge
Formal Structure
ExecutiveLegislative
Bureaucracy
Informal Structure
Policy BrokersCoalitions
StakeholdersCitizens
Values
IdeologiesViews about
what ought tobe
BeliefsCausal
assumptionsabout what is
InterestsResponses to
incentivesand rewards
Policies
Factors Influencing Policy Process
Importance of Value Systems on Interpretation of Scientific
Information
Role of the Precautionary Principle
Limitations of evidence
In 1986 BSE is discovered in the UK no epidemiological evidence exists of harm,
however there is a theoretical risk of transmission
UK chose not to take actions to halt spread of BSE important health impact, enormous financial
impact, undermined confidence in public health
In 1980s concern emerged about potential blood transmission of HIV and Hepatitis C no epidemiological evidence exists of harm,
however there was a theoretical risk of transmission
Canada chose not to take full measures to protect blood supply from HIV, Hep C enormous health and financial impact,
undermined confidence in blood system
Both government responses criticized for not taking precautionary measures
“the safety of the blood supply is an aspect of public health, and, therefore, the blood supply system must be governed by the public health philosophy, which rejects the view that complete knowledge of a public health hazard is a prerequisite for action.” Justice Krever
The Precautionary Principle
The precautionary principle emerged out of the European environmental movement of the 1970’s and has its roots in the German concept of Vorsorge or foresight.
The principle reflects a recognition of the limitations of scientific models to accurately describe complex issues pertaining to environmental harm or health risk
Impact
Since the time of its introduction, the precautionary principle has had a substantial impact on environmental policy
It has been incorporated into the 1992 Rio Declaration on Environment and Development and the Maastricht Treaty Establishing the European Community
Definition
The precautionary principle essentially states that complete evidence of risk does not have to exist to protect individuals and society from the risk “Better to be safe than sorry” “An ounce of prevention is worth a pound of
cure”
“When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. In this context the proponent of an activity, rather than the public, should bear the burden of proof.” Wingspread Statement
“Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.” Rio Declaration
Interpretations of the Principle
Stronger interpretations burden of responsibility on the proponents of
potentially harmful measures
Weaker interpretations burden of proof on those arguing the
possibility of harm
Core Concepts
(1) advocating anticipatory action to prevent harm
(2) shifting some of the burden of proof to the proponents of new technologies to demonstrate safety
(3) advocating a consideration of all alternatives to a new technology including doing nothing
(4) incorporation of all affected parties in the decision- making process of adopting a new technology
Problems with Precaution
Policy makers have had difficulty in agreeing on how much or how little evidence is required to trigger a precautionary action and on the role of the scientific process when the principle is utilized
The variability in the interpretation of the principle has led to accusations that the principle has been used as a mechanism to introduce trade protectionism.
The principle has also been accused of producing over regulation denying the public the benefits of new
technologies arousing unnecessary fear in the public about
theoretical risks
Applications
Primarily has been used in the environmental sector
Increasingly being used in the health sector
Implications of applying an “environmental” measure to the health sector has not been fully examined
Challenge of Balancing Competing Risks
“recognizing that in the application of the precautionary principle strictly to health, that there are some potential problems in exercising restraint … when it involves a therapeutic product, the absence of (which) may in itself have a risk consequence to a patient population”
Is the Precautionary Principle Useful in Public Health?
Double Edged Sword
Environmental Sector Balance benefits to health and the
environment versus economic and technological losses
Health Sector Balance benefits to health against possible
health consequences
Examples of inappropriate Precaution
DDT and environmental harm Banned because of environmental harm based on animal
evidence Increase in malaria deaths
Chlorine and cancer Peru banned chlorine because of carcinogenic fears Cholera outbreak followed
GMO’s and biodiversity EU banned import of GMO’s due to theoretical fears of harm Zambia refused large donation of GMO’s in the presence of
famine
Proposed Solutions
Proportionality Non-discrimination Consistency Examining costs and benefits Subject to review Assigning responsibility for producing
scientific evidence
How can the Precautionary Principle be applied?
4 mechanisms of application of the Precautionary Principle
Mechanism Example
Strong Precaution
Introduction of full precautionary measure to eliminate perceived risk
European Commission position
on importing genetically
modified foods
Intermediate Approach
Introduction of partial precautionary measure designed to balance risk
prevented by implementation of precaution versus risk created by
introduction of precaution (risk-management approach)
US and Canadian policy on
blood donations from
individuals at risk of vCJD
Weak Precaution
Delayed introduction of precautionary measure until mechanisms
instituted to protect against health risk created by introducing
precautionary measure
Stockholm Convention position
on DDT
Evidence-Based Approach
Deferral of precautionary measure until more definitive
epidemiological evidence becomes available
US FDA position on phthalates
in cosmetic products
The precautionary principle and evidence-based policy
The fundamental question related to application of the precautionary principle is what is an acceptable level of uncertainty of risk How much systematic and random error are
policy makers willing to accept
Level of acceptable certainty of causal association
Low HighExposure Wide Narrow
Outcomes Serious Treatable/reversible
Cost of risk factor removal Inexpensive Expensive
Negative effects (e.g. health) of risk factor removal
Limited Serious
Follow-up to vCJD Donor deferral decision
Subsequent events
Extended to all of Europe UK residency period reduced to 3 months Canada and US have first cases of vCJD Animal studies suggest blood transmission
is possible Four case reports of transfusion
transmission
Relationship of Evidence to Policy
Year Policy Evidence
1996 vCJD discoveredtheoretical transfusiontransmission risk suspected
1997 UK announces decision to recall bloodcomponents/plasma derivatives fromindividuals later diagnosed with vCJD
1998 UK chooses to import plasma tomanufacture fractionated products
France and UK introduce universalleukoreduction
1999 Canada and the US introduce donordeferral policies
2000 France introduces UK donor deferralpolicy
Preliminary report of sheep tosheep transfusion transmission ofBSE
2001
2002 Confirmation of sheep to sheeptransfusion transmission in bothpre-clinical and clinical animals
2003 UK decision to import fresh frozen plasma for use in patients born after January 1996
Human case report of vCJD inrecipient of transfusion from avCJD donorEfficiency of BSE transmissionIn primates, efficiency of BSEtransmission demonstrated to beat least as efficient via transfusiontransmission as by the oral route
Growth of expenditure on blood and blood products in Canada
0
100
200
300
400
500
600
700
1998-1999 1999-2000 2000-2001 2001-2002
Years
In M
illi
on
s o
f $
Blood operations
Fractionated products
Captive insurance
Total
Advantages Disadvantages
Protects against recallslong term cost benefitprotection against shortagesavoids recipient notificationchallenges
Potential protection from alarge scale health riskMaintains trust in bloodsystemMaintains trust in publichealth
Short term cost No definitive evidence ofriskDiscourages donorsReduction in blood supply
Evaluation of Precaution in the vCJD donor deferral decision
Conclusions
The precautionary principle in its broadest context is a useful and necessary tool to policy makers.
In order for it to be an effective policy guide further refinements to the principle are needed and a precautionary principle specific for the health sector needs to be developed.
Questions ?