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Improving Prognostic Web Calculators: Violation of Preferential Risk Independence
Farrokh Alemi1,2, Cari Levy3, Bruce A Citron4
11 The District of Columbia Veteran Administration Medical Center , Washington.
Journal of Palliative Medicine
|September 14, 2016
Summary
Prognostic models for groups can mislead individual patient care. This study shows how average risk scores can be paradoxical, emphasizing the need for unconfounded risk predictions in clinical decision-making.
Area of Science:
- Biostatistics
- Clinical Epidemiology
- Medical Informatics
Background:
- Web-based prognostic tools are common for patient risk assessment.
- These models are typically developed using group data, not individual patient profiles.
- Applying group averages to individuals can lead to inaccurate and misleading clinical decisions.
Purpose of the Study:
- To illustrate paradoxical outcomes when using average prognostic indices for individual patient care.
- To explain how group-level prognoses can misinform individual patient management.
- To introduce preferential risk independence as a method to identify and correct such anomalies.
Main Methods:
- Calculated expected mortality risks for stomach cancer and comorbidities.
- Utilized data from 140,699 residents of Veterans Administration nursing homes.
- Employed the mathematical concept of preferential risk independence to analyze risk anomalies.
Main Results:
- Hypertension typically increases mortality risk but was found to be protective in lung cancer patients.
- This paradox arises because average lung cancer prognosis reflects co-occurring comorbidities.
- Hypertension's presence in lung cancer patients may indicate fewer severe comorbidities, not a protective effect of hypertension itself.
Conclusions:
- Average risk scores from web calculators can be misleading for individual patients.
- Reporting unconfounded risks can enhance the accuracy of prognostic predictions.
- Clinical decision-making should move beyond average risk scores to more precise, individual-specific predictions.
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