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Three disease types—cancers, vascular events, and infections— account for nearly 75% of all misdiagnosis-related harms. Additionally, 15 subgroups of these diseases make up nearly 50% of high-severity cases. These statistics call for targeted improvements in diagnostic accuracy, according to researchers from the Johns Hopkins University School of Medicine, who combed through more than 55,000 claims to arrive at these findings.

The United States sees anywhere from 40,000 to 4 million serious misdiagnosis-related harms each year. To assess the burden of these errors in the healthcare system, David Newman-Toker, MD, PhD and his colleagues looked through the Controlled Risk Insurance Company’s Comparative Benchmarking System database, which represents nearly 29% of all U.S. malpractice claims. “Our main goal was to identify the list of top diseases that, when missed, cause serious harms so that in later research steps we could measure their annual incidence, frequency of diagnostic errors, and risk of harm to approximate incident harms,” the researchers explained. Agency for Healthcare Research and Quality Clinical Classifications Software (CCS) was used to categorize or group diseases.

Researchers analyzed the frequency, severity, and settings of cancers, vascular events, and infections, three conditions known to cause the most death and morbidity in diagnostic errors. Using the National Association of Insurance Commissioners (NAIC) Severity of Injury Scale, they defined high-severity harms on a score range of 6 to 9 (serious, permanent disability, or death).

Overall, the researchers determined that inaccurate or delayed diagnoses accounted for 34% of all malpractice cases that resulted in death or permanent disability. From a pool of 55,377 closed claims, they extracted more than 11,500 diagnostic error cases, 53% of which fell into the category of high-severity harms. Cancers, vascular events, and infections accounted for about 74% or three-fourths of these cases, including misdiagnosed cancers (37.8%), vascular events (22.8%), and infections (13.5%). “These severe cases resulted in $1.8 billion in malpractice payouts over 10 years,” according to a statement from the Society to Improve Diagnosis in Medicine (SIDM).

Breaking it down further, top five high-severity harms from each of the three categories accounted for 47.1% of all high severity cases. Lung cancer, stroke, and sepsis had the highest prevalence among cancers, vascular events, and infections, respectively. Across settings, results varied among the top three categories. Inpatient and emergency departments (ED) saw a higher prevalence of infections and vascular events, whereas cancers dominated in non-ED ambulatory clinics.

Clinical judgment surpassed communication problems or closing the loop on test results as the biggest cause of error, accounting for about 85% of the cases. “This result accords with prior work indicating that the vast majority of diagnostic process failures happen in bedside assessment and clinical reasoning (many of which appear to derive from knowledge gaps) and points to a need for solutions that support better bedside clinical decisionmaking,” the authors suggested. A variety of tools such as device-based decision support and automated image interpretation as well as improvements to support diagnostic education could assist with this goal.

“If we’re going to reduce serious harms from medical errors, major strides must be made to improve diagnostic accuracy and timeliness. 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,” said Newman-Toker, professor of neurology at the Johns Hopkins University School of Medicine and director of the Johns Hopkins Armstrong Institute for Patient Safety and Quality’s Center for Diagnostic Excellence. He and his colleagues recommended targeting interventions in hot button areas, such as lung cancer in primary care, stroke in EDs, and sepsis in hospitals, to improve diagnoses for high-harm conditions.

SIDM’s ACT for Better Diagnosis program has gathered more than 50 patient advocacy and healthcare organizations—including AACC— to address diagnostic errors and work on solutions to improve diagnostic safety and quality. Its initiatives include education, research, patient engagement, and practice improvements, with a goal to raise awareness about diagnostic errors and to reduce patient harm.