What is Diagnostic Error?

Common, Costly, and Harmful

Diagnostic error is one of the most important safety problems in health care today, and inflicts the most harm. Major diagnostic errors are found in 10% to 20% of autopsies, suggesting that 40,000 to 80,000 patients die annually in the U.S. from diagnostic errors.

Patient surveys confirm that at least one person in three has firsthand experience with a diagnostic error, and researchers have found that diagnostic errors—not surgical mistakes, or medication overdoses—account for the largest fraction of malpractice claims, the most severe patient harm, and the highest total of penalty payouts.

It is likely that most of us will experience at least one diagnostic error in our lifetimes, sometimes with devastating consequences.
-Improving Diagnosis in Health Care

Diagnostic Error Defined

The National Academy of Medicine (formerly the Institute of Medicine) defined diagnostic error as the failure to (a) establish an accurate and timely explanation of the patient’s health problem(s) or (b) communicate that explanation to the patient.

Simply put, these are diagnoses that are delayed, wrong, or missed altogether.

These categories overlap, but examples help illustrate some differences:

  • delayed diagnosis refers to a case where the diagnosis should have been made earlier. Delayed diagnosis of cancer is by far the leading entity in this category. A major problem in this regard is that there are very few good guidelines on making a timely diagnosis, and many illnesses aren’t suspected until symptoms persist, or worsen.
  • wrong diagnosis occurs, for example, if a patient truly having a heart attack is told their pain is from acid indigestion. The original diagnosis is found to be incorrect because the true cause is discovered later.
  • missed diagnosis refers to a patient whose medical complaints are never explained. Many patients with chronic fatigue, or chronic pain fall into this category, as well as patients with more specific complaints that are never accurately diagnosed.

Factors in Diagnostic Error

Diagnostic error stems from the complexity of the diagnostic process, complexities in how health care is delivered, and the same kinds of cognitive errors that we all make in our everyday lives.

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Frequently Asked Questions

Learn the important questions and answers when it comes to diagnostic error, including causes, most commonly misdiagnosed diseases, and what you can do to reduce your chances of receiving a misdiagnosis.

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Improving Diagnosis in Health Care

It is likely that most of us will experience at least one diagnostic error in our lifetimes, sometimes with devastating consequences. Read the seminal report, published by the National Academy of Medicine, on improving diagnosis.

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Foundational Readings

Explore the diagnostic error literature base and access dozens of academic articles that cover concepts, challenges, and avenues for diagnostic improvement.