Evidence on Methods for Communicating Health-Related Probabilities: Comparing the Making Numbers Meaningful...

Area of Science:

• Health communication research
• Decision science
• Systematic review methodology

Background:

• Effective communication of health probabilities is crucial for patient decision-making.
• The 2021 International Patient Decision Aids Standards (IPDAS) Collaboration provided recommendations for presenting probabilities.
• The Making Numbers Meaningful (MNM) systematic review synthesized evidence on data presentation formats for health numbers.

Purpose of the Study:

• To evaluate the extent to which the MNM systematic review's findings support the IPDAS recommendations on probability presentation.
• To identify areas where evidence is strong, weak, or lacking for specific IPDAS recommendations.

Main Methods:

• Conducted a systematic review (MNM) of 316 papers, generating 1,119 findings on health number communication.
• Classified findings by audience task, stimulus type (data, format), and outcomes (e.g., perception, behavior, trust).
• Summarized MNM findings in relation to each of the 35 IPDAS recommendations.

Main Results:

• Strong evidence supports IPDAS recommendations for part-to-whole graphical formats (e.g., icon arrays) and consistent denominators.
• Evidence supports avoiding verbal probability terms, 1-in-X formats, and relative risk formats to prevent biased perceptions and intentions.
• Evidence is weaker for IPDAS recommendations on numerical estimates in context and evaluative labels; further research is needed on uncertainty and interactive formats.

Conclusions:

• No single format is optimal for all probability communication situations, a consensus between IPDAS and MNM.
• While no MNM evidence contradicts IPDAS, the evidence base supporting many common recommendations is incomplete.
• Further research is necessary to strengthen the evidence for numerous probability communication best practices in patient decision aids.