What is Diagnostic Error? - Society to Improve Diagnosis in Medicine (2024)

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 Academies of Sciences, Engineering, and Medicine defined diagnostic erroras 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:

• Adelayed diagnosisrefers 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.
• Awrong diagnosisoccurs, 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.
• Amissed diagnosisrefers 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.

Inaccurate or Delayed Diagnosis: Common, Costly, and Harmful

Inaccurate or delayed diagnosis is one of the most important safety problems in healthcare today, and inflicts the most harm.

• According to the 2015 U.S. National Academies of Sciences, Engineering, and Medicine quality report, Improving Diagnosis in Health Care, diagnostic errors represent a major public health problem likely to affect every one of us at least once in our lifetime, sometimes with devastating consequences.¹
• At a minimum, wrong or delayed diagnoses cause more serious harms to patients than any other type of medical error,² and 40,000-80,000 people die each year from diagnostic failures in U.S. hospitals alone.³
• Diagnostic errors affect more than 12 million Americans each year⁴ and may seriously harm one-third of these patients,⁵ likely dwarfing all other causes of harm from medical errors combined.
• Improving the accuracy and timeliness of diagnoses will reduce costs from inappropriate testing, wrong treatments, and malpractice lawsuits, potentially saving over $100­­ billion per year.⁶
• Diagnostic errors are the most common cause of medical errors reported by patients. ⁷
• Diagnostic errors—not surgical mistakes or medication overdoses—accounted for the largest fraction of malpractice claims, the most severe patient harm, and the highest total of penalty payouts.⁸
• Despite the enormous toll of wrong or delayed diagnoses on lives and resources, federal funding for research to tackle this problem remains minimal, totaling just a few million dollars each year. ⁹