Verbal Probability Terms for Communicating Clinical Risk - a Systematic Review

Area of Science:

• Medical Communication
• Health Literacy
• Risk Perception

Background:

• Verbal probability expressions are widely used in healthcare to convey uncertainty.
• Inconsistent interpretation of these terms can lead to miscommunication between patients and healthcare professionals.
• Standardizing probability terms can improve the clarity and consistency of risk communication.

Approach:

• A systematic review was conducted to evaluate the numeric meanings of common probability terms.
• Studies assessing the interpretation of probability terms by laypersons and healthcare professionals were analyzed.
• A Visual Risk Scale was constructed using terms with reliable numeric interpretations.

Key Points:

• Five probability terms demonstrated consistent interpretation: 'Very Likely' (90%), 'Likely/Probable' (70%), 'Possible' (40%), 'Unlikely' (20%), and 'Very Unlikely' (10%).
• Corresponding frequency terms were identified: Very Frequently, Frequently, Often, Infrequently, and Rarely.
• Recommended presentation of numeric values is X-in-100 natural frequency statements, avoiding percentages or other formats.

Conclusions:

• Verbal probability terms can be interpreted consistently when standardized.
• Presenting probability terms with their numeric ranges and using natural frequency statements (X-in-100) enhances patient understanding.
• The Visual Risk Scale can aid shared decision-making in clinical practice.