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Diagnostic errors called most harmful, costly medical mistakes

Misdiagnoses were responsible for the costliest and deadliest portion of US malpractice claims during the last 25 years, according to new research.

After reviewing 350,706 malpractice payments through the National Practitioner Data Bank (1986 to 2010), Johns Hopkins University investigators found that diagnostic errors led all types (28.6%) and also were the costliest type, responsible for 35.2% of total payments, or an inflation-adjusted $38.8 billion.

“This is more evidence that diagnostic errors could easily be the biggest patient safety and medical malpractice problem in the United States,” said researcher David E. Newman-Toker, MD, PhD, associate professor of neurology at the Johns Hopkins University School of Medicine.

David E. Newman-Toker

Researchers defined a diagnostic error as one that is missed, wrong or delayed, as determined later through a definitive finding or test.

Diagnostic errors resulted in death more often than other allegation types (40% vs. 23.9%; P<.001). Researchers also found that outpatient diagnostic error claims were more frequent than inpatient claims (68.8% vs. 31.2%; P<.001), but inpatient claims had a higher risk for lethality (48.4% vs. 36.9%; P<.001). Mean time between the diagnostic act or omission and payment was 4.7 years. Most payments (n=93,035) were on behalf of allopathic and osteopathic physicians.

Although researchers analyzed only claims that resulted in malpractice payouts, they estimated that 80,000 to 160,000 US patients experience significant impacts annually from misdiagnoses, including “potentially preventable, significant permanent morbidity or mortality.”

“Overall, diagnostic errors have been underappreciated 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,” Newman-Toker said. “These are frequent problems that have played second fiddle to medical and surgical errors, which are evident more immediately.”