Misdiagnosis of diseases or medical conditions leads to hundreds of thousands of deaths and permanent disabilities each year in the United States, according to a report published this week.
Approximately 371,000 people die and 424,000 sustain permanent disabilities—such as brain damage, blindness, loss of limbs or organs, or metastasized cancer—annually as a result of misdiagnoses.
To arrive at these estimates, researchers analyzed data from dozens of earlier studies to determine how often certain conditions were missed and the frequency with which those misses resulted in serious harm.
This risk was then scaled according to the incidence rate of new cases in the U.S. population.
“Patients should not panic or lose faith in the health care system,” the researchers wrote in the study. There is less than a 0.1% chance of serious harm related to misdiagnosis after a health care visit.
Nearly 40% of severe outcomes, including death and permanent disability, are linked to errors in diagnosing five conditions: stroke, sepsis, pneumonia, venous thromboembolism (a blood clot in a vein), and lung cancer.
“These are relatively common diseases that are missed relatively commonly and are associated with significant amounts of harm,” said Dr. David Newman-Toker, a neurologist at Johns Hopkins University.
He led the study’s research team from the Johns Hopkins Armstrong Institute Center for Diagnostic Excellence, in collaboration with researchers from the Risk Management Foundation of Harvard Medical Institutions Inc.
Although these five conditions are not the most frequently misdiagnosed, they have the largest impact, and the study findings can help prioritize areas for investment and interventions, he said.
Spinal abscess, an infection of the central nervous system, is misdiagnosed more than 60% of the time, according to the report.
However, with only 14,000 new cases each year, this leads to about 5,000 serious harms—a relatively small portion of the burden of diagnostic error.
Stroke, identified in the report as the leading cause of serious harm, is a common condition with a high risk of severe outcomes, and it is misdiagnosed more often than average.
About 950,000 people have a stroke each year in the U.S., and it is missed in about 18% of cases, leading to approximately 94,000 serious harms annually.
Diagnostic errors often result from attributing non-specific symptoms to more common and less serious conditions than the actual cause, experts say.
“Occasionally, we have people who get inappropriate treatments for a disease they don’t have, and they suffer harms from that,” Newman-Toker said.
“Much more common is a life-threatening disease that is missed because the manifestations are milder or less obvious.”
When someone has trouble speaking and moving an arm, it is easy to diagnose a stroke. However, a stroke can also cause dizziness or headache, symptoms that can be indicative of many other conditions.
Heart attacks can cause vague symptoms such as general chest pain. Despite this, they are significantly less likely to be misdiagnosed, with less than a 2% error rate, according to the report.
Success in diagnosing heart attacks has required decades of concentrated efforts, Newman-Toker said.
The process began by acknowledging misdiagnosis as a problem, leading to investments in research and the establishment of regulatory requirements for performance monitoring.
“You end up ultimately with a system of care that focuses on not missing heart attacks,” he said. “It’s the model for what we could be doing.”
Generally, diagnostic errors differ from other patient safety issues—such as surgeries performed on the wrong site, falls, or medication errors—because the link between an action and an outcome is less direct, explained Dr. Daniel Yang, an internist and program director for the diagnostic excellence initiative at the Gordon and Betty Moore Foundation.
“Diagnostic errors are errors of omission,” said Yang, who was not involved in the new study.
“The question is: Could [the outcome] be prevented if we had done something differently earlier on? Oftentimes, that’s a judgment call that two doctors might disagree on.”
Broader systemic issues within the healthcare system complicate this process.
“The diagnostic journey is really not a single decision at one point in time,” Yang said. “It’s an odyssey that unravels over days, weeks, months, even years. It cuts across multiple care settings and different types of doctors.”
However, various points of care are often disconnected, and providers may lack a comprehensive understanding of a patient’s history.
This fragmentation—with scattered records from encounters with primary care, specialists, clinics, and emergency rooms—creates opportunities for information to be lost, leaving patients to piece together their own medical history.
A 2015 report from the National Academies of Sciences, Engineering, and Medicine highlighted ways patients could be proactive in their diagnostic journey.
It included a checklist for maintaining a good record of personal medical history, staying informed about relevant conditions, tests, and medications, and following up with providers with questions about any changes or next steps.
The study specifically addresses diagnostic errors among patients seen in healthcare settings.
However, the burden is likely much larger when considering those who did not seek care and therefore received delayed diagnoses and suboptimal treatment, Yang said.
“The hospital can provide perfect diagnostic care. But if someone spends months waiting to see a doctor in the first place, it doesn’t matter how good the healthcare system is, because the stage of diagnosis is going to be later,” he said.
