Diagnostic errors linked to nearly 800,000 deaths or cases of permanent disability in US each year, study estimates

By Deidre McPhillips, CNN

(CNN) — Misdiagnosis of disease or other 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.

About 371,000 people die and 424,000 sustain permanent disabilities – such as brain damage, blindness, loss of limbs or organs or metastasized cancer – each year as a result.

To make the estimate, researchers pulled from dozens of earlier studies to assess how often certain conditions were missed and how often that miss led to serious harms. That risk was then scaled by the incidence rate of new cases in the total US population.

“Patients should not panic or lose faith in the health care system,” the researchers wrote in the study. Overall, there’s less than a 0.1% chance of serious harms related to misdiagnosis after a health care visit.

Nearly 40% of those severe outcomes including death and permanent disability are linked to errors in diagnosing a group of 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 partnership with researchers from the Risk Management Foundation of Harvard Medical Institutions Inc.

Although those five conditions aren’t 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. But with 14,000 new cases each year overall, that leads to about 5,000 serious harms – a relatively small portion of the overall burden of diagnostic error.

But stroke, which the report found to be the top cause of serious harms, is a relatively common condition with a high risk of severe outcomes, and it’s misdiagnosed more often than average. About 950,000 people have a stroke each year in the US, and it’s missed in about 18% of cases, according to the report – leading to about 94,000 serious harms each year.

Diagnostic errors are typically the result of attributing non-specific symptoms to something more common and perhaps less serious than the condition that is actually causing it, 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’s easy to diagnose a stroke. But a stroke can also cause dizziness or headache, which can be symptoms of many other things.

Heart attacks can also cause vague symptoms such as general chest pain. But they are significantly less likely to be misdiagnosed, with less than a 2% error rate, according to the report.

The success in diagnosing heart attacks required decade of concentrated efforts, Newman-Toker said. The process started by recognizing that misdiagnosis was a problem, which led to investment of funds into research and regulatory requirements around monitoring performance.

“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, though, diagnostic errors are different than other areas of patient safety – such as surgeries that are done on the wrong site, falls or medication errors – because the link between an action and a result is less direct, said 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.”

And broader systemic issues in the health care system challenge that process.

“The diagnostic journey is really not a single decision at one point of time,” Yang said. “It’s an odyssey that unravels overnight, in some cases, days, weeks, months, even years. It cuts across multiple care settings and different types of doctors.”

But various points of care are disconnected, and providers often don’t have a full understanding of patient’s history, he said. That fragmentation – with scattered records from each encounter with primary care, specialists, clinics and emergency rooms – presents opportunities for information to be lost along the way, leaving the patient to put all the puzzle pieces together on their own.

A 2015 report from the National Academies of Sciences, Engineering, and Medicine highlighted ways that patients could play a role in their own diagnostic journey, with a checklist that includes keeping 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 captures diagnostic error among patients seen in health care settings. But the burden is probably significantly larger when factoring in all those people who didn’t seek care and can’t receive optimal treatment because their diagnosis is happening later than it should, 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 health care system is, because the stage of diagnosis is going to be later,” he said.

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