UMEM Educational Pearls

Category: Neurology

Title: What Affects Patient Decision on Head CT in mild TBI?

Keywords: traumatic brain injury, clinical decision rule, CT utilization, patient decision, benefit, risk, financial incentive (PubMed Search)

Posted: 5/14/2020 by WanTsu Wendy Chang, MD (Updated: 8/17/2022)
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  • Previous studies suggest more than 1/3 of head CTs are avoidable by evidence-based guidelines.
  • It is controversial whether patients respond to financial incentives for healthy behavior.
  • A study by Iyengar et al. surveyed 913 ED patients using a hypothetical mild TBI scenario that does not need a head CT by the Canadian CT Head Rule.
  • Patients were randomly assigned the consideration of benefit (0.1% of 1%), risk (0.1% or 1%), or financial incentive ($0 or $100) associated with obtaining a head CT.
  • Overall, 54.2% (495/913) patients elected to obtain a head CT.
    • An increase in test benefit was associated with a 9.3% increase in CT use (49.6% to 58.9%).
    • An increase in test risk was associated with a 10.2% decrease in CT use (59.3% to 49.1%).
    • An increase in financial incentive was associated with a 11.7% decrease in CT use (60.6% to 48.3%).

Bottom Line: Discussion of benefit/risk and financial incentive associated with head CT in mild TBI affects patient decision. Interestingly in this population studied, more than half of patients will elect to obtain a head CT even in a low-risk scenario.


Iyengar R, Winkels JL, Smith CM, et al. The effect of financial incentives on patient decisions to undergo low-value head CT scans. Acad Emerg Med. 2019;26(10):1118-24.

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