"These are the most common and the most costly of all malpractice claims," said study author Dr. David Newman-Toker, an associate professor of neurology at the Johns Hopkins University School of Medicine, in Baltimore. "We have to pay attention to this because it is too big of a problem to ignore."
In the new study, researchers analyzed diagnosis-related claims from a national data bank from 1986 to 2010. Of all the claims, diagnostic errors led the pack, accounting for about 35 percent of the total payments of $38.8 billion (after adjusting for inflation). The study only reviewed claims that involved a malpractice payout, not those that did not get this far in the process.
Diagnosis-related claims were the leading cause of claims-associated death and disability. Most diagnostic errors occurred in outpatients, but those that occurred while a person was in the hospital were more likely to be fatal, the study showed.
The researchers estimated that the number of misdiagnosis-related claims that cause preventable, permanent damage or death may be as high as 160,000 each year.
The new finding appeared online April 22 in BMJ Quality & Safety.
"We really have to make it a priority to measure and track diagnostic errors on an ongoing basis as we do other mistakes such as infection and wrong-site surgery," Newman-Toker said. "They are completely underrepresented in terms of what we pay attention to."
Errors can happen anywhere along the way. "It can be wrong diagnosis, no diagnosis or delayed diagnosis," he said. "If you get the diagnosis wrong, the chances of getting the therapy right are greatly reduced."
Sometimes, these mistakes can be fatal right off of the bat. "If someone has a headache, and you say 'take two aspirin and call me in the morning,' but the headache is really a brain aneurysm, the patient could die before morning," Newman-Toker added.
Patients are not powerless. "Even great doctors make mistakes," he said. "Ask, 'is there anything else this can be?'" he advised. "If the doctor says 'no' [then] ask 'why?' and an answer such as 'because it's the only thing it could be' is not good enough."
Dr. David Troxel, medical director of The Doctors Company, a malpractice insurer based in Napa, Calif., said the study "provides valuable information to caregivers about medical errors."
"I believe that the disclosure of this information will enhance patient safety," Troxel said. "Patients can also play an important role in reducing the incidence of diagnostic errors by providing their doctor with an accurate medical history, adhering to the prescribed follow-up plan, keeping return visit appointments to discuss abnormal test results and asking questions to clarify instructions they don't clearly understand."
Malpractice attorney Michael Sacopulos, CEO for the Medical Risk Institute in Terre Haute, Ind., said he was surprised by the extent of the new findings. "Maybe things get off course right at the beginning, but this has not been studied as much as other errors that result in malpractice suits," he said.
Still "medicine is an art and not a science so this will happen," Sacopulos said. "Patients need to be persistent with physicians because so often the doctor will make a diagnosis and over time, it becomes clear that it was wrong. The first attempt may not be accurate. Think of it as a work in progress instead of being written in stone."
Learn more about patient safety at the National Patient Safety Foundation.