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Post Hoc Bias in Treatment Decisions.
Donald A Redelmeier1,2,3,4,5, Eldar Shafir6,7
1Department of Medicine, University of Toronto, Toronto, Ontario, Canada.
JAMA Network Open
|September 4, 2024
Summary
A small symptom improvement after dubious treatments encourages continued use, even when ineffective. This post hoc bias can lead to complacency and hinder effective healthcare choices.
Area of Science:
- Cognitive psychology
- Health services research
- Clinical decision-making
Background:
- Continuing ineffective treatments can lead to complacency, discourage seeking alternatives, and result in care shortfalls.
- Understanding biases in treatment continuation is crucial for improving healthcare outcomes.
Purpose of the Study:
- To investigate the post hoc bias, where marginal symptom improvement after a dubious treatment influences continued use.
- To assess whether this bias affects both community members and healthcare professionals.
Main Methods:
- Hypothetical patient scenarios were presented to community members and pharmacists via online and in-person surveys.
- Respondents were randomized to versions where symptoms marginally improved or remained unchanged after a dubious treatment.
- The primary outcome measured was the recommendation to continue the treatment.
Main Results:
- Participants were significantly more likely to recommend continuing dubious treatments (antibiotics, copper bracelet, vitamin B12) when symptoms showed marginal improvement compared to no change.
- This effect was observed across multiple scenarios and included healthcare professionals.
- Odds ratios for continuing treatment ranged from 3.98 to 16.19, with P-values < .001.
Conclusions:
- Marginal symptom improvement following dubious treatments can lead to their continuation, demonstrating a significant post hoc bias.
- Clinicians should be aware of and caution patients against this bias to prevent the use of ineffective and potentially costly treatments.
- Addressing this cognitive bias is essential for promoting evidence-based healthcare and preventing care shortfalls.
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