A study from the Johns Hopkins University School of Medicine has identified that a misdiagnosis or delayed diagnosis is behind one-third of the malpractice cases that end in permanent disability or death. The study, published in 2019, notes that some 40,000 to 80,000 deaths in U.S. hospitals are linked to misdiagnosis each year and that around 12 million Americans are subjected to a diagnostic error in a primary care setting. Some 33% of these either are fatal or result in serious injury. Results identified that of the most harmful diagnostic errors, 74.1% were attributable to just three categories of conditions: cancer (37.8%), vascular events (22.8%), and infection (13.5% ). These severe cases resulted in $1.8 billion in malpractice payouts over ten years. The cross-sectional analysis, which focused on an extensive medical malpractice claims database, was the first of a three-phase project to gauge the U.S. burden of serious misdiagnosis-related harms. 

The researchers noted, “Serious morbidity is about as common as mortality, so diagnostic safety and quality measures must take this into account…Mortality more often reflects missed non-neurologic vascular events/infections, while severe morbidity more often reflects missed neurologic, vascular events/infections or cancer delay.” The analysis confirms that delayed or inaccurate diagnosis continues to be the most common, catastrophic, and costly medical error. It also provides additional context for a 2015 National Academy of Medicine report that said diagnostic errors in U.S. hospitals resulted in nearly 80,000 deaths.

“It is not just inconvenient to have a wrong or delayed diagnosis. For many patients, misdiagnosis causes severe harm and expense, and in the worst cases, death,” said David Newman-Toker, MD, Ph.D., lead author of the research and director of the Johns Hopkins Armstrong Institute for Patient Safety and Quality’s Center for Diagnostic Excellence. “If we’re going to reduce serious harms from medical errors, major strides must be made to improve diagnostic accuracy and timeliness,” Dr. Newman-Toker continued. 

“This study shows us where to focus to start making a difference for patients. It tells us that tackling diagnosis in these three specific disease areas could have a major impact on reducing misdiagnosis-related harms,” added Paul L. Epner, CEO and co-founder of the Society to Improve Diagnosis in Medicine: “This work showcases that myriad factors contribute to missed and delayed diagnosis and highlights the need for further collaboration across the healthcare system to significantly improve diagnosis and ensure the best possible outcomes for patients.”

The authors note that future research should try to clarify the relationship between harms in malpractice claims and damages in real-world clinical practice, especially with cancer, which they point out appears to be over-represented in claims.