A Risk-Characterization Framework for Decision-Making at the Food and Drug Administration (2011) / Chapter Skim
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2 A Risk-Characterization Framework
2 A Risk-Characterization Framework
Pages 17-45
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From page 17... ...
Health consequences are only a subset of the large array of factors that must be considered for any given problem. However, they constitute a reasonable place to start the process of developing a decision framework inasmuch as such factors loom large in most FDA decisions and substantial work has already been done on methods for estimating the human-health consequences associated with various risks, hazards, and decisions.
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From page 18... ...
Step 3. Use the completed characterization as a way to compare decision options and to communicate their public-health consequences within the agency, to decision-makers, and to the public; use the comparison with other decisionrelevant information to make informed decisions.
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Specifically, the bulk of Science and Decisions focuses on the risk-assessment portion in phase II of the framework, as is highlighted in the figure. The framework proposed here focuses on the riskcharacterization portion of the decision structure and adopts a more robust view of the importance of risk characterization in the overall process of making riskinformed decisions.
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From page 20... ...
The present committee adopts the broader view of risk characterization and its relationship to risk-informed decision-making. PHASE I: PHASE II: PHASE III: PROBLEM FORMULATION PLANNING AND CONDUCT RISK MANAGEMENT AND SCOPING OF RISK ASSESSMENT Stage 1: Planning • For the given decision context, what are the attributes of assessments necessary to characterize risks of existing conditions and the effects on risk of proposed options?
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From page 21... ...
. The framework defined here builds on that work while embracing the notion that risk characterization should be decision-focused rather than restricted to ranking risks.
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From page 22... ...
Two decision options are considered -- remove or do not remove the vaccine from the market. In this case study, the committee determined that it was important to consider the health consequences of both the vaccine and the underlying disease that the vaccine is intended to prevent.
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From page 23... ...
When different allocations of resources are expected to be equally effective in reducing the risks associated with the product or product category in question, a ranking of potential targets according to unreduced risk may provide sufficient decision support. For example, in making decisions about what facilities to inspect in a specific year, CFSAN may be able to use a risk ranking of facilities in their current conditions and operations with the assumption that additional resources will be equally effective in reducing the risks at
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From page 24... ...
To create such a risk ranking, FDA would need to estimate the public-health consequences of the food products from each facility that is a candidate for inspection -- or, more generally, for each potential target of the resource allocation -- on the basis of its best assessment of the current conditions and operations of the facilities. The resulting ranked list could then be used as the basis of resource-allocation decisions.
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From page 25... ...
The case study allows some comparisons to be made but probably represents a narrower scope of strategic-investment options than what FDA would consider. CHARACTERIZING THE HEALTH CONSEQUENCES OF DECISION OPTIONS In the risk-assessment paradigm, risks have traditionally been characterized by a single attribute, such as the number of deaths that could occur as a result of the hazard being evaluated or the probability that an exposed individual will experience an identified adverse effect.
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From page 26... ...
Deciding whether the risk of a serious adverse effect outweighs the benefits in increased mobility and quality of life is not a technical or scientific question but rather a question of personal and societal values. An integral part of the committee's proposed approach is that it characterizes various effects explicitly so that decision-makers can make informed decisions that account for them rather than combining them into a single metric based on implicit weightings (see Box 2-1)
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From page 27... ...
The committee finds that a richer characterization of the public-health consequences of decision options is needed for routine comparison of deci sion options. As described in Improving Risk Communication, "reducing different kinds of hazard to a common metric (such as number of fatalities per year)
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To address that need, the committee identified a second set of risk attributes on the basis of the risk-ranking and riskperception literature: personal controllability, ability to detect adverse health effects, and the ability to mitigate (or reduce) adverse effects.
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that may have higher exposure or be more sensitive to potential adverse effects of that exposure than the general population. For example, if the exposed population consisted disproportionately of children, that fact should be included in the summary.
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. The risks associated with the decision options being evaluated should be characterized by the number of people who would suffer from each of the types of adverse health effects annually.
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Ability to Detect Adverse Health Effects Ability to detect adverse health effects refers to the ability of informed institutions to detect population-level adverse effects that result from the use (or absence) of the product that is being considered.
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for them to be detected and correctly attributed. Ability to Mitigate Adverse Health Effects Ability to mitigate adverse health effects refers to the ability of institutions to manage, reduce, or otherwise control any expected or unexpected adverse health effects associated with the product that is being evaluated, assuming that such effects exist and are detected.
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From page 33... ...
in a year attributable to the product or resource c) Number of people who suffer other adverse health effects in a year attributable to the product or resource serious enough to affect quality of life Personal Percentage of the exposed population who have sufficient knowledge and controllability alternatives available that they could control or reduce their personal risk from the product being evaluated Ability to Any one of the following, as appropriate for the decision being evaluated: detect adverse Probability that a problem will be detected if it occurs health effects Frequency with which unexpected adverse effects would have to occur in the exposed population to be recognized Increase in the base rate of occurrence of the adverse effect caused by the product being evaluated that would be sufficient to be recognized Ability to Probability that an informed institution will be able to reduce (mitigate)
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From page 34... ...
Using the Risk Attributes to Characterize Health Consequences Using a single set of risk attributes with specified metrics to characterize the public-health consequences of different decisions entails substantial complexities. First is the wide array of decisions that FDA must make, as described in Chapter 1 and elaborated in the discussion of decision context above.
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From page 35... ...
Delaying a critical decision until additional information can be collected may be an option in some circumstances, but it should not be considered the "default" decision when uncertainty exists. Instead, all relevant options, including the option to delay a decision until later or to allocate scarce resources to additional data collection or model development, should be evaluated on the basis of the best available information, including expert judgment, about the public-health consequences of the decision.
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From page 36... ...
Statistical methods based on judgment, in which expert judgments and Bayesian approaches to statistical analysis are included, often in com bination with "hard" data. Other quantitative methods that involve approaches not based on probability theory, such as interval methods, fuzzy methods, and meta analytic methods.
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From page 37... ...
That approach is demonstrated in the case studies that follow this chapter. Options for succinctly describing a probability distribution vary; however, the shorthand notation should be able to provide an indication of a distribution's first three moments -- central tendency, spread, and skew -- and should be easily assessable from data, model output, or expert judgment.
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From page 38... ...
. Explicit evaluation and presentation of uncertainty in risk assessments reduces the problem of false precision, makes risk characterization more informative, and increases the credibility of any ensuing risk communication.
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From page 39... ...
The goal is to have a risk characterization that includes representation of the uncertainty in the size of the exposed population, in the number of deaths that may occur, and in the number of injuries or illnesses that may occur under various decision options. Rather than ask simply for a range or for low and high estimates of those quantities, the committee suggests using the concepts associated with the percentiles of a distribution as a way to ensure consistent assessment and interpretation of the low and high values.
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From page 40... ...
However, careful and consistent evaluation of the public-health consequences of various options is an essential component of good decision-making, and there are several ways in which the risk characterizations described here could be used in decisionmaking. One approach was outlined in the committee's letter report, which focused on developing a risk ranking (see Appendix A)
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From page 41... ...
Alternatively, the quantitative public-health consequences as a group may be considered relevant, and it may be considered useful to combine the attributes in the risk characterization into a single metric to compare options. Such integrative measures may be easier to develop, and especially valuable, when there is a logical set of mathematical relationships between the various attributes.
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Presentation at the 5th Meeting on Ranking FDA Product Categories Based on Health Consequences, Phase II, February 3, 2010, Washington, DC. Bronfman, N.C., L.A.
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2011. FDA's Fresh Produce Risk Ranking Tool.
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2000. Categorizing risks for risk ranking.
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From page 45... ...
2004. Eco logical risk ranking: Development and evaluation of a method for improving pub lic participation in environmental decision making.
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