diagnostic error
@Kristan Jacobsen
Diagnostic Error
A missed diagnosis can delay treatment or result in inappropriate treatment, causing unnecessary pain, suffering, and often financial hardship for our patients. Internist and hospitalist Peter Yarbrough helps explain why diagnostic errors happen with strategies to prevent them.

Case Study

Mr. Pauls had pneumonia–or so it seemed. The 90 year old patient did not have leukocytosis or abnormal chest x-ray, however, given his dementia, recurrent aspiration, and cough, pneumonia seemed likely. But after two days of antibiotic therapy, his clinical condition hadn’t changed. The team decided to pursue further evaluation and he was found to have an acute pulmonary embolism. In retrospect, this diagnosis actually made more clinical sense. What happened here?

What is diagnostic error?

In its 2015 report Improving Diagnosis in Health Care, the Institute of Medicine (IOM) defines diagnostic error two ways: (1) “The failure to establish an accurate and timely explanation of the patient’s health problems” or (2) “The failure to communicate that explanation to the patient.”

The second part of that definition aligns with patient-centered care and the patient perception of error. Every week, U of U Health system receives nearly The Five Elements of Patient Experience from patients. Sometimes patients describe diagnostic errors–an incorrect test that leads the patient to return to get retested, incorrect medications, at times, diagnoses that turn out to be wrong.

Patients describe these experiences as scary and often confusing. When an error occurs, it not only affects a patient’s trust and confidence in their provider, but also reduces trust in the entire health care system.

Impact of diagnostic error

Why is this important? Most of us will experience a diagnostic error in our lifetime. A missed diagnosis can delay important treatment or result in inappropriate treatment, often causing patients unnecessary physical pain, psychological suffering, and financial hardship.

Understanding why diagnostic errors happen is harder. Much of the research on this subject has focused on cognitive errors, which contribute to 74% of diagnostic errors. Faulty knowledge or skill was much rarer, accounting for less than 4% of diagnostic errors.

How do we prevent diagnostic error?

There are two primary recommendations for preventing diagnostic errors: provider-based recognition of cognitive errors (common biases and influence our thinking) and system-based approaches.

1. Provider-based approaches

Making a diagnosis typically involves a combination of analytical thinking and non-analytical thinking—recognizing patterns or applying mental shortcuts called heuristics. Each mode of thinking is prone to error; recognizing and attempting to mitigate the most common types of errors may then reduce diagnostic error.

Be aware of common biases that influence decision making. Our case study is an example of premature closure, the most common type of cognitive error that occurs when a diagnosis is made and thinking stops. This can result in the failure to consider additional tests and diagnoses. Contributing factors to premature closure include confirmation bias (seeking information to support an initial diagnosis rather than thoroughly evaluating additional data, availability bias (tending to diagnose diseases recently seen, and base rate neglect (neglecting prevalence of disease when considering diagnosis).

Be consistent in decision making. Perpetual high alert is not a strategy. The following strategies may help to avoid diagnostic error:

diagnostic error table
  1. Think aloud: Talking through your thought process while making a diagnosis.
  2. Commit and confirm: Commit to a diagnosis and think about what data supports or refutes that diagnosis.
  3. Check-in: Every time you encounter the patient (next appointment or next time you round), continually reassess the diagnosis made and the response to therapy—is it still appropriate?

2. System-based approaches

Consistent with quality improvement and patient safety principles, addressing diagnostic error requires multiple areas of focus. At the system level, creating and reinforcing a no-blame culture of continuous improvement helps providers and teams evaluate diagnoses and learn from missed diagnoses.

Build a no-blame culture. The historical shame-and-blame culture of medicine applies individual blame to errors, instead of identifying and addressing system-based improvements. One study indicated that only half of physicians in training thought that errors were handled appropriately at their institution; nearly a third thought they would be criticized for making mistakes. One goal of patient safety is to create a culture committed to addressing concerns, respecting all parties involved, and creating an environment where people are comfortable drawing attention to medical errors.

Report diagnostic errors to prevent future errors. A cornerstone of safety culture is reporting these events and near-misses so that they can be evaluated and addressed. Every facility has a mechanism for reporting safety events. These reports can be centrally evaluated to examine cross-service trends and system-wide issues that need to be addressed. Without frontline reporting, it is difficult to learn from errors and try to prevent them in the future.


What could have mitigated the error in our introduction case study? The team initially made the common cognitive error of premature closure–a diagnosis was made and thinking stopped. But they didn’t stop there. The team did the right thing by ordering additional testing and then acting on the new information. Diagnostic errors will happen. It’s important that we not assign individual blame and continue to think critically about diagnoses during the course of a patient’s care.



Peter Yarbrough

Internist and Hospitalist, George E. Wahlen Veterans Affairs Hospital; Assistant Professor of Medicine, University of Utah Health

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