Misdiagnosing patients or making diagnostic errors is one of the most costly and dangerous mistakes made by doctors in the U.S., resulting in up to 160,000 deaths per year.

Johns Hopkins researchers have reviewed over 350,000 malpractice claim payouts in the U.S over the past 25 years. They found that most of the claims were due to diagnostic errors, and that those errors were often the cause of severe patient harm and accounted for the highest total payouts.

Between 1986 and 2010 the total diagnosis-related payments were close to $38.8 billion.

The leader of the study, which was published in BMJ Quality and Safety, David E. Newman-Toker, M.D., Ph.D., an associate professor of neurology at the Johns Hopkins University School of Medicine, said:

“This is more evidence that diagnostic errors could easily be the biggest patient safety and medical malpractice problem in the United States. There’s a lot more harm associated with diagnostic errors than we imagined.”

The study only looked at claims that were at the level of malpractice payout, though the researchers estimate that there are around 80,000 to 160,000 patients suffering misdiagnosis-related injury or death in the U.S.

In a previous malpractice analysis by researchers at Johns Hopkins, they revealed that a surgeon in the United States leaves a foreign object such as a sponge or a towel inside a patient’s body after an operation 39 times a week.

Diagnostic errors are identified through some sort of additional testing or finding. The errors result in failure to adequately treat the patient’s present condition.

Newman-Toker said:

“Overall, diagnostic errors have been under appreciated and under-recognized because they’re difficult to measure and keep track of owing to the frequent gap between the time the error occurs and when it’s detected. These are frequent problems that have played second fiddle to medical and surgical errors, which are evident more immediately.”

He added: “Progress has been made confronting other types of patient harm, but there’s probably not going to be a magic-bullet solution for diagnostic errors because they are more complex and diverse than other patient safety issues. We’re going to need a lot more people focusing their efforts on this issue if we’re going to successfully tackle it.”

The researchers used data from the National Practitioner Data Bank, which has been keeping a record of all payments made by healthcare professionals in the United States concerning malpractice settlements for over 20 years.

They identified a total of 350,706 different claims, of which 28.6 percent were due to diagnostic errors – accounting for 35.2 percent of total payments.

Compared to other error categories, diagnostic errors were responsible for far more deaths or disabilities.

Even though the majority of the diagnostic errors were in outpatient care rather than inpatient care (68.8 percent vs 31.2 percent), inpatient errors resulted in more deaths.

The researchers noted that most of the diagnostic mistakes were missed diagnoses as opposed to wrong ones. Cases that involved serious neurologic harm (such as brain damage) were the highest per-claim payments.

In addition, they found that the number of diagnostic errors resulting in death was very similar to the number of cases that caused permanent harm to patients, indicating that diagnostic mistakes have a far greater public health impact than previously thought.

Newman-Toker said that the toll of mistaken diagnoses could be far greater than the data the team analyzed, with some experts estimating that a diagnostic error occurs in close to 15% of patients when they see a doctor for the first time concerning a new problem.

A previous report revealed that $54.4 billion is spent annually on medical malpractice systems; 2.4% of America’s health care spending.

Newman concluded that “there just hasn’t been enough attention paid to this.”

Written by Joseph Nordqvist