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Counting the cost of fatal misdiagnoses – BMJ study

A recent study has estimated that overlooking a disease, or diagnosing it erroneously or late, results in 371 000 people dying in the US every year and 424 000 being permanently disabled – although the researchers say settling on an exact number is difficult because many cases go undetected.

Misdiagnoses are not unknown in health care, and can have tragic effects, but there have been few attempts to quantify these in terms of deaths and permanent disability, with a 2015 report by the National Academy of Medicine saying the full scale of their impact has been underestimated by the medical community.

However, the latest study, published in The BMJ, finally addresses that gap, finding that 800 000 people suffered “serious harm”, according to David Newman-Toker, the lead author of the paper and a professor of neurology at Johns Hopkins School of Medicine and director of its Centre for Diagnostic Excellence.

Settling on an exact number is hard because of missed diagnoses, and the figure could be fewer than his study identified, or more – between half a million and a million – though in any event, it would be the most common cause of death or disability due to medical malpractice, he observed.

“We focused here on the serious harms, but the number of diagnostic errors in the US each year is probably somewhere on the order of magnitude of 50 to 100m,” he told STAT News. “If you actually look, you see it’s happening all the time.”

But misdiagnoses typically don’t lead to severe consequences, because most times people aren’t visiting the doctor with a serious condition. “The risk level – just walking through the door in the doctor’s office that something horrible is going to happen to you because of a diagnostic error – is actually quite low,” he said.

However, that’s different, though, for the minority of people who walk into the doctor’s office with serious, potentially fatal, conditions, for example, someone who feels dizzy because of the onset of a stroke, but is diagnosed with vertigo instead, or a young woman whose breast cancer is missed during a routine check-up.

For them, the study found, the risk of death associated with misdiagnosis is 4%, and the risk of severe disability 11%.

Solutions within reach

Analysing the nature of misdiagnoses also provides significant opportunities for solutions. The errors are many, but they are quite concentrated. According to the study, 15 diseases account for about half the misdiagnoses, and five diseases alone – stroke, sepsis, pneumonia, venous thromboembolism, and lung cancer – caused 300 000 serious harms, or almost 40% of the total, because clinicians failed to identify them in patients.

“That’s a lot that you could accomplish if you cut those harms by 50% for just those five diseases. That would be 150 000 prevented serious permanent disabilities or death,” said Newman-Toker.

The overwhelming reason for misdiagnosis is cognitive error on the part of the doctor, he said.

Doctors may make poor diagnostic decisions because the signs of the disease aren’t typical, or because the symptoms are too common and not frequently associated with a severe disease: dizziness, for instance, occurs in a majority of cases of stroke, but only very few cases of dizziness result in stroke.

Or, it may be an issue of bias, either circumstantial – for instance, overlooking the possibility that a young patient may be having a stroke, because it’s exceedingly rare – or systemic, resulting for instance in dismissal of symptoms reported by black patients. (Newman-Toker said his research estimates that being a woman or a person of colour increases chances of misdiagnoses by 20% to 30%.)

This means that finding a way to avoid such cognitive errors, at least in the most commonly misdiagnosed severe diseases, would save many lives.

But how?

Routinely incorporating a second opinion in visits was one way, suggested Newman-Toker. “The quickest way would be to construct approaches that basically rely on the ‘phone a friend’ model.”

This doesn’t mean that the patient should have to seek a second opinion, but rather that providers should make it standard practice to consult with a colleague before providing a diagnosis or dismissing a patient.

The economic burden

The study findings also provide insight into the economic burden of misdiagnoses, something that has so far been hard to quantify due to the lack of a reliable estimate of occurrences.

To explain the huge cost of misdiagnoses, William Padula, an assistant professor of pharmaceutical and health economics at the University of Southern California, who did not participate in the study, also uses a missed stroke example – it is the most commonly misdiagnosed severe condition, so much so that AI is being tested as a solution.

“A patient comes into the ED with a headache or dizziness and they get told it’ll go away, and then they go home. A week later, you find out they had a stroke,” he said. ”By then, the stroke has compounded so much that what could have been addressed in the moment … for $10 000 now becomes a $100 000 issue. … So there’s a margin of $90 000 that has been added to the health system burden because of the misdiagnosis.”

Multiply that for hundreds of thousands of misdiagnoses and the total costs are exorbitant, in the order of $100bn, and possibly untold billions of dollars more, said Padula, especially considering societal costs such as years of lost productivity due to premature death or disability.

This helps put into perspective the costs that would be incurred to get a second opinion, or to add extra tests to rule out certain conditions. “It’s a cost-effective solution upfront to spend the extra money to more accurately diagnose patients,” said Padula.

Yet, the funding for research to improve diagnoses is extremely limited – proportional to, Newman-Toker said, the insufficient political (and medical) importance given to the issue.

“The amount of federal research dollars support that’s going to address this problem is around $20m to $30m a year,” he said. Before 2016 the federal funding was even lower, at $7m a year, he said, but it was raised as more data came out on the impact of misdiagnoses.

That amounts to about $50 per death – a pittance, he said, considering the investment made in researching treatment for some serious diseases (like certain cancers) can run as high as $400 000 per every death recorded from the disease.

Study details

Burden of serious harms from diagnostic error in the USA

David Newman-Toker, Najlla Nassery, Dana Siegal, et al.

Published in The BMJ in July 2023


Diagnostic errors cause substantial preventable harms worldwide, but rigorous estimates for total burden are lacking. We previously estimated diagnostic error and serious harm rates for key dangerous diseases in major disease categories and validated plausible ranges using clinical experts.

We sought to estimate the annual US burden of serious misdiagnosis-related harms (permanent morbidity, mortality) by combining prior results with rigorous estimates of disease incidence.

Cross-sectional analysis of US-based nationally representative observational data. We estimated annual incident vascular events and infections from 21.5m (M) sampled US hospital discharges (2012–2014). Annual new cancers were taken from US-based registries (2014). Years were selected for coding consistency with prior literature. Disease-specific incidences for 15 major vascular events, infections and cancers (‘Big Three’ categories) were multiplied by literature-based rates to derive diagnostic errors and serious harms. We calculated uncertainty estimates using Monte Carlo simulations. Validity checks included sensitivity analyses and comparison with prior published estimates.

Annual US incidence was 6.0 M vascular events, 6.2 M infections and 1.5 M cancers. Per ‘Big Three’ dangerous disease case, weighted mean error and serious harm rates were 11.1% and 4.4%, respectively. Extrapolating to all diseases (including non-‘Big Three’ dangerous disease categories), we estimated total serious harms annually in the USA to be 795 000 (plausible range 598 000–1 023 000). Sensitivity analyses using more conservative assumptions estimated 549 000 serious harms. Results were compatible with setting-specific serious harm estimates from inpatient, emergency department and ambulatory care. The 15 dangerous diseases accounted for 50.7% of total serious harms and the top 5 (stroke, sepsis, pneumonia, venous thromboembolism and lung cancer) accounted for 38.7%.

An estimated 795 000 Americans become permanently disabled or die annually across care settings because dangerous diseases are misdiagnosed. Just 15 diseases account for about half of all serious harms, so the problem may be more tractable than previously imagined.


The BMJ article – Burden of serious harms from diagnostic error in the USA (Open access)


STAT News article – Misdiagnoses cost the U.S. 800,000 deaths and serious disabilities every year, study finds (Open access)


See more from MedicalBrief archives:


Doctors to pay $29m after misdiagnosis and death


CHIPS: Widespread misdiagnosis and mismanagement of cluster headaches


Study finds childhood cancer substantially undiagnosed










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