Cognitive Biases in Emergency Medicine
Cognitive biases are systematic errors in thinking that affect how we process information and make decisions. In EMS, these biases can lead to missed diagnoses, inappropriate treatments, and patient harm. Understanding common biases is the first step toward mitigating their effects on your clinical practice.
Common Biases in EMS
Premature Closure
Premature closure occurs when you arrive at a diagnosis before gathering all relevant information. For example, dispatching tells you the call is for a "drunk person." You arrive, find an adult male who smells of alcohol and is slurring his words, and assume intoxication without checking blood glucose, performing a neurological exam, or considering other causes of altered mental status like stroke, head injury, or hypoglycemia.
Availability Bias
Availability bias causes you to overestimate the probability of diagnoses you have seen recently or that made a strong impression. If you transported a patient with a pulmonary embolism last week, you may be more likely to suspect PE in your next patient with shortness of breath, even if the presentation is more consistent with asthma or pneumonia.
Diagnostic Momentum
Once a working diagnosis is established, it tends to carry forward through the healthcare system. If first responders report "chest pain, probable cardiac," subsequent providers may anchor on that impression without independently evaluating the patient. The patient's epigastric discomfort from a GI bleed may go unrecognized because everyone assumed it was cardiac.
Debiasing Strategies
- Maintain a broad differential: Generate at least three possible diagnoses for every patient before settling on one
- Actively seek disconfirming evidence: Ask yourself, "What findings would make me reconsider my working diagnosis?"
- Use cognitive forcing strategies: Pause before finalizing your clinical impression and deliberately consider alternatives
- Apply clinical decision rules: Use validated tools (Cincinnati Stroke Scale, Ottawa Ankle Rules) to supplement your clinical judgment
- Invite challenge: Encourage your partner to question your clinical reasoning
Biases are not signs of incompetence. They are features of how human cognition works under pressure. The best providers are not those who never experience bias but those who recognize when bias might be influencing their decisions and take steps to counteract it.