Individual risk

Area of Science:

• Biostatistics
• Clinical Decision-Making
• Epidemiology

Background:

• Patient risk assessment is complex, often relying on statistical models.
• Current models frequently present "individual risk" as a definitive probability.
• This approach has inherent limitations due to the nature of probability and risk factors.

Purpose of the Study:

• To critically evaluate the concept and reliability of "individual risk" in clinical settings.
• To explain the reference class problem and its implications for risk prediction.
• To propose alternative approaches for more robust clinical decision-making.

Main Methods:

• Conceptual analysis of probability and risk assessment.
• Historical review of the reference class problem (John Venn, 1866).
• Critique of current risk modeling practices in medicine.

Main Results:

• "Individual risk" is an unreliable concept outside of Mendelian inheritance, representing conditional probabilities.
• Risk estimates vary substantially based on the inclusion of different risk factors.
• No reliable method exists to calculate a unique, true individual risk for a given outcome.

Conclusions:

• The concept of individual risk is fundamentally flawed and should not be used as the sole criterion for clinical decisions.
• Clinically important subgroups and direct clinical measures (e.g., blood pressure) are more reliable for decision-making.
• Adopting subgroup-based assessments aligns with established statistical principles and improves clinical judgment.