The National Academy of Medicine (NAM) has called diagnostic error a “blind spot” for modern medicine and improving diagnosis a “moral, professional, and public health imperative.” Diagnostic errors – inaccurate or delayed diagnoses – “persist throughout all settings of care and continue to harm an unacceptable number of patients. It is likely that most people will experience at least one diagnostic error in their lifetime, sometimes with devastating consequences.”

And a new study released Thursday by the Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services, with the assistance of Johns Hopkins University Evidence-based Practice Center in Baltimore, estimates that roughly 7.4 million people are inaccurately diagnosed of the 130 million annual visits to hospital emergency departments in the United States. Some 370,000 patients may suffer serious harm as a result.

The Agency for Healthcare Research and Quality (AHRQ), through its Evidence-based Practice Centers (EPCs), sponsors the development of systematic reviews to assist public- and private-sector organizations in their efforts to improve the quality of healthcare in the United States.

The literature review used for this study covered publication dates from January 2000 to September 2021, and identified 19,127 abstracts, screened 1,455 full text studies, and included 279 studies that addressed the key issues of the study.

The top 15 clinical conditions associated with serious misdiagnosis-related harms were (1) stroke, (2) myocardial infarction, (3) aortic aneurysm and dissection, (4) spinal cord compression and injury, (5) venous thromboembolism, (6) meningitis and encephalitis, (7) sepsis, (8) lung cancer, (9) traumatic brain injury and traumatic intracranial hemorrhage, (10) arterial thromboembolism, (11) spinal and intracranial abscess, (12) cardiac arrhythmia, (13) pneumonia, (14) gastrointestinal perforation and rupture, and (15) intestinal obstruction.

Average disease-specific error rates ranged from 1.5 percent (myocardial infarction) to 56 percent (spinal abscess), An estimated 5.7 percent of all ED visits had at least one diagnostic error.

If overall rates are generalizable to all U.S. ED visits, this would translate to 7.4 million ED diagnostic errors annually; 2.6 million diagnostic adverse events with preventable harms; and 371,000 serious misdiagnosis-related harms, including more than 100,000 permanent, high-severity disabilities and 250,000 deaths.

Key process failures were errors in diagnostic assessment, test ordering, and test interpretation. Most often these were attributed to inadequate knowledge, skills, or reasoning, particularly in “atypical” or otherwise subtle case presentations.

Although estimated ED error rates are low (and comparable to those found in other clinical settings), the number of patients potentially impacted is large. Not all diagnostic errors or harms are preventable, but wide variability in diagnostic error rates across diseases, symptoms, and hospitals suggests improvement is possible.

However, the New York Times reports that the study was met with criticism from the American College of Emergency Physicians, whose president called the conclusions “misleading, incomplete and erroneous,” and said the reliance on studies conducted outside of the U.S. may have led to overestimates of mistakes.

In a statement to the Times, the group’s president, Christopher Kang, MD, said, “The report conveys a tone that inaccurately characterizes and unnecessarily disparages the practice of emergency medicine in the United States,” and, “While most medical specialties have similar training in Western nations, emergency medicine does not.”