Emergency Medicine Cases
Episode 62 Diagnostic Decision Making in Emergency Medicine
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This is Part 1 of EM Cases' series on Diagnostic Decision Making with Walter Himmel, Chris Hicks and David Dushenski discussing the intersection of evidence-based medicine, cognitive bias and systems issues to effect our diagnostic decision making in Emergency Medicine. In this episode we first discuss 5 strategies to help you master evidence-based diagnostic decision making to minimize diagnostic error, avoid over-testing and improve patient care including:
1. The incorporation of patients' values and clinical expertise into evidence-based decisions
2. Critically appraising diagnostic studies
3. Understanding that diagnostic tests are not perfect
4. Using the concept of test threshold to guide work-ups
5. Understanding that the predictive value of a test depends on the prevalence of disease
We then go on to review some of the factors that play into the clinician’s and patient’s risk tolerance in a given clinical encounter, how this plays into shared decision making and the need to adjust our risk tolerance in critical situations. Finally, we present some strategies to prevent over-testing while improving patient care, patient flow and ethical practice.
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Written Summary and blog-post Prepared by Dr. Anton Helman, April 2015
Are doctors effective diagnosticians?
Diagnostic errors accounted for 17% of preventable errors in medical practice in the Harvard Medical Practice Study and a systematic review of autopsy studies conducted over four decades found that nearly 1 in 10 patients suffered a major ante-mortem diagnostic error; a figure that has fallen by only approximately 5% despite all of todays’ advanced imaging technology and increased testing utilization.
The factors that contribute to diagnostic error (adapted from the Ottawa M&M model (http://www.ncbi.nlm.nih.gov/pubmed/24628757)) include patient factors such as a language barrier, clinician factors such as knowledge base, fatigue or emotional distress; cognitive biases (reviewed in Episode 11 (http://emergencymedicinecases.com/episode-11-cognitive-decision-making-medical-error/) with Chris Hicks and Doug Sinclair), teamwork failure, systems or process failure, and wider community issues such as access to care. A greater awareness of these factors that contribute to diagnostic error may improve the clinician's diagnostic accuracy and improve patient outcomes.
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Five Strategies to master evidence-based diagnostic decision making
* Evidence Based Medicine incorporates patient values and clinical expertise - not only the evidence
For an explanation of the interaction of the 3 spheres of EBM see Episode 49: Walter Himmel on Evidence Based Medicine from the NYGH EMU Conference 2014 (http://emergencymedicinecases.com/episode-47-walter-himmel-evidence-based-medicine-nygh-emu-conference-2014/)
   The intent of EBM is to…
Make the ethical care of the patient its top priority
Demand individualised evidence in a format that clinicians and patients can understand
Use expert judgement rather than mechanical rule following
Share decisions with patients through meaningful conversations
Communicate risk whilst incorporating the patient’s values
Apply these principles at the community level for evidence based public health
* Critically Appraise Diagnostic Studies
     Critical Appraisal Checklist (adapted from Best Evidence in Emergency Medicine)
* Is the clinical problem well defined?
* Does the study population represent the target population (is there any spectrum bias)?
* Does the study population focus on ED patients or are they ICU patients, or admitted patients?
* Did the study recruit patients consecutively (was there a selection bias)?
* Was the diagnostic evaluation sufficiently comprehensive and applied equally to all patients (was there no verification bias)?