Cancer, vascular events, and infection—the “Big three”—account for three-fourths of high-harm, diagnosis-related claims

Boston, MA— Researchers from Johns Hopkins University School of Medicine and CRICO found that 74 percent of inaccurate or delayed diagnoses that result in permanent disability or death are attributable to three disease categories: cancer, vascular events, and infections. The new research appears in the peer-reviewed journal, Diagnosis.

Researchers analyzed CRICO Strategies’ Comparative Benchmarking System (CBS)—a database of more than 400,000 malpractice claims drawn from more than 400 academic and community medical centers, and is estimated to contain 30 percent of all malpractice claims in the United States. The study examined approximately 55,000 malpractice claims from CBS to determine how many were attributable to diagnostic error. The research was funded by the Society to Improve Diagnosis in Medicine (SIDM) through a grant from the Gordon and Betty Moore Foundation. 

Of malpractice claims attributable to diagnostic error, researchers reviewed underlying disease states to identify patterns of misdiagnosis. They found that of the diagnostic errors causing the most harm, three quarters (74.1%) are 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 10 years. The authors also showed that, collectively, the top five in each category account for nearly half (47.1%) of all the serious harms.

“For many patients, misdiagnosis causes severe harm and expense, and in the worst cases, death,” said David Newman-Toker,MD, PhD, professor of neurology at the Johns Hopkins University School of Medicine and director of the Johns Hopkins Armstrong Institute for Patient Safety and Quality Center for Diagnostic Excellence, who served as lead author of the research. Dr. Newman-Toker is also president of the Board of SIDM. “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.”

The research confirms that inaccurate or delayed diagnosis remains the most common, most catastrophic and most costly of medical errors. The analysis provides additional context for a 2015 National Academy of Medicine report that highlighted that diagnostic errors result in up to 80,000 deaths annually in U.S. hospitals.

“We have long been focused on analyzing medical malpractice data to better understand the key drivers of diagnostic error and patient harm,” says Dana Siegal, RN, CPHRM, CPPS, director of patient safety for CRICO Strategies. Siegal co-led the research with Dr. Newman-Toker and serves on the SIDM Board of Directors. Siegal continues, “Medical malpractice data is a valuable tool we have to understand medical error. Our coding allows deep data analysis to highlight patterns and drivers of risk. The insights gained from this new research will help organizations know where to direct their focus to improve the diagnostic process of care.”

An inaccurate or delayed diagnosis is about the complete care delivery process and associated with all members of the health care team, including patients. It will take system-wide efforts and study authors also noted that research and quality improvement efforts need to focus on interventions in the specific practice settings where the harm occurs such as “stroke in the emergency department, sepsis in the hospital, and lung cancer in primary care.”


The researchers sought to identify diseases accounting for the majority of serious misdiagnosis-related harms (morbidity/mortality). Diagnostic error cases were identified from CRICO Strategies’ Comparative Benchmarking System database (2006-2015). Diseases were grouped according to the Agency for Healthcare Research and Quality’s Clinical Classifications Software that aggregates International Classification of Diseases diagnostic codes into clinically sensible groupings. The researchers analyzed vascular events, infections, and cancers, including frequency, severity, and settings. High-severity harms were defined by scores of 6-9 (serious, permanent disability or death) on the National Association of Insurance Commissioners Severity of Injury Scale.


CRICO Strategies, now Candello, ( is a division of The Risk Management Foundation of the Harvard Medical Institutions Incorporated, a CRICO company. The CRICO insurance program is a group of companies owned by and serving the Harvard medical community. CRICO Strategies’ mission is to unite the medical and insurance communities into a single voice with reliable and actionable data as our shared language. Partnering with national organizations, CRICO Strategies works to strengthen their ability to reduce medical malpractice risks with powerful analytics of more than 400,000 cases of harm and loss and expertise that help get results.

The Society to Improve Diagnosis in Medicine (SIDM) ( catalyzes and leads change to improve diagnosis and eliminate harm from diagnostic error. We work in partnership with patients, their families, the healthcare community and every interested stakeholder.SIDM is the only organization focused solely on the problem of diagnostic error and improving the accuracy and timeliness of diagnosis. In 2015, SIDM established the Coalition to Improve Diagnosis to increase awareness and actions that improve diagnosis. Members of the Coalition represent hundreds of thousands of healthcare providers and patients—and the leading health organizations and government agencies involved in patient care. Together, we work to find solutions that enhance diagnostic safety and quality, reduce harm, and ultimately, ensure better health outcomes for patients.

For immediate release: July 12, 2019

Media Contact:
Mike Paskavitz
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