Skip to content Skip to main navigation

Task 2

Blood safety risk assessment


Determine the risk to blood safety and the impact of the risk management options on this risk

Save spot Save spot

Procedures and expectations for blood safety risk assessment usually include:

  • Applying formal methods (qualitative and quantitative) to review the evidence
  • Being clear about the assumptions made to conduct the assessment
  • Using mathematical methods to estimate variability of inputs, probability of risk and level of uncertainty
  • Using ‘weight of evidence’ methods to draw conclusions

Note: The analysis requires specialized expertise that can usually be found in the blood operator’s Medical or Epidemiological department.

An online tool called EUFRAT (European Up-Front Risk Assessment Tool) can help estimate the transmission risk of emerging infectious diseases. It guides the user through five steps: 1) Prevalence of infection among donors, 2) Risk of obtaining infected donations, 3) Infected components, 4) Infected blood products, and 5) Risk of transmission to recipients.

Step 1
Frame the problem


Describe the objective and scope of the assessment.


  • Clearly state the objective of this assessment. A blood safety risk can be explained in terms of outcomes, such as an adverse event in a blood recipient, or in terms of policy goals, such as improving the efficiency of a process.
  • Establish the scope of the assessment — whether it can be short and focused or needs to go into greater depth. Provide a rationale for your decision.
  • Determine the type and level of detail of the information required by decision-makers.
  • Outline how this assessment will interact with other assessments (e.g., health economic) to ensure that elements not covered here are covered elsewhere.
  • Select the risk measures — the types of calculations or estimates you will use to assess blood safety risk and its human impacts.

Step 2
Identify the hazard(s)


Identify and describe the different ways that adverse events can arise from the hazard to blood safety.


  • Identify the hazard causing the blood safety risk and determine the adverse events that could result.
  • Examine the evidence that the hazard and adverse outcomes are linked.
    • Obtain evidence from the scientific literature (e.g., hemovigilance data, surveillance information).
    • When reviewing different studies, you may need to give them different weightings.
  • Prepare a written summary of the hazard and its possible impacts.
  • Pay careful attention to the data you include and exclude and your process for weighting the evidence. Consider the weight of different studies and sources of uncertainty.
  • Be transparent about the processes you are using.

Step 3
Assess hazard exposure


Estimate the extent of exposure and how much harm it may do to risk bearers.


  • Decide on the required depth of investigation of risk sources and pathways (e.g., all sources, all risk bearers, all pathways, or a more limited scope).
  • Using scientific and technical arguments, determine the most important combinations of hazard sources and risk bearers. This subset will be the focus of your risk analysis.
  • Using qualitative and quantitative methods, estimate the probability (how often the hazard will occur)  and extent of exposure ( how much harm it may do) to the blood safety risk.
  • Describe the possible adverse outcomes from the blood safety risk; include both minor, reversible outcomes (e.g. minor febrile reaction) and more serious, irreversible impacts, such as fatalities or chronic disability ( sepsis).
  • Estimate the probability, rate, and extent of damage (from the adverse outcomes identified above) to risk bearers exposed to the hazard. Give appropriate weight to these populations in your risk estimate.

Step 4
Characterise the blood safety risk


Integrate the hazard information into a conclusion about blood safety risk.


  • Estimate the overall blood safety risk by merging your estimates for
    1. probability and extent of exposure and
    2. probability, rate, and extent of damage from adverse outcomes.
  • Describe the level of uncertainty in any components or results of the risk assessment.
  • Prepare a brief summary of your analysis and results, specifying the populations considered and the level of uncertainty/variability in risk.
  • Integrate the risk estimates with the economic analysis.

Further information on Blood Safety Risk Assessments

  • Various methods can simplify the characterization, such as average population risk or percentile cut-offs to describe risk distribution.
  • Method for assessing and expressing uncertainty include bounding values, interval analysis, sensitivity analysis, importance analysis, and analysis of different scenarios. The choice methods should be explained.
  • Baseline assumptions (e.g. interpretation of scientific data) should be clarified; the choice of method should be explained.

Step 5
Assess the impact of the risk management options


Estimate the benefits (i.e. level of risk reduction) of the risk management options you identified earlier.


  • Evaluate how effectively each risk management option may have an impact on risk by:
    • Reducing the probability of adverse outcomes
    • Reducing the severity of adverse outcomes
    • Possibly creating new risks
    • Any other known effects
  • Identify the risk trade-offs created by the risk management options.
  • Prepare a summary of the change in risk levels (compared to status quo) for each risk management option. This summary may be one of the inputs in your evaluation.
    • Use descriptions as specific as possible. Avoid generic statements like “a significant reduction,” “reduces the risk to safe levels.”

Step 6
Integrate the results into the Options Evaluation table

Integrate the results of this analysis with the results of other assessments.


  • Summarise the blood safety risk assessment results for each risk management option in the Blood Safety Summary table.

NEXT: Stage 4 Task 3  >

  • Task 1
  • Task 2
  • Task 3
  • Task 4
  • Task 5
  • Task 6