“The Big Three” for Diagnostic Error

A 2019 study looking at harms related to misdiagnosis was published in the medical journal Diagnosis, the official journal of the Society to Improve Diagnosis in Medicine (SIDM). The study was led by Dr. David E. Newman-Toker, a professor of neurology at the Johns Hopkins University School of Medicine.¹

Important findings from the paper were presented at a Capitol Hill briefing sponsored by the SIDM and funded through the Gordon and Betty Moore Foundation. This presentation was meant to bring awareness and inspire healthcare-related changes when it comes to the serious harms of misdiagnosis.¹

What are the Big Three?

The study identified “the Big Three” health events that involve misdiagnosis and, more specifically, misdiagnosis-related harms. These Big Three were cancers, vascular events, and infections. The researchers analyzed over 55,000 total malpractice claims and determined that these 3 conditions were major players involved in misdiagnosis-related harms.¹

The claims spanned the years 2006 to 2015, and the data came from the Controlled Risk Insurance Company’s Comparative Benchmarking System. This database is thought to represent about 30 percent of all malpractice cases in the United States.¹

Of all the malpractice cases they analyzed, close to 12,000 (just over 20 percent) were related to diagnostic error. Almost 7,400 of these diagnostic error-related cases were deemed severe, with an outcome of permanent disability or death.¹

Misdiagnoses related to the Big Three made up over 60 percent of all diagnostic error cases and over two-thirds of all diagnostic error payouts. But the Big Three made up almost 75 percent of cases that resulted in permanent disability or death. This suggests that not only are the Big Three common in misdiagnosis situations, but they are also often associated with some of the most serious outcomes.¹

Cancer’s role in the Big Three

Of the Big Three-related cases that resulted in disability or death from diagnostic error, nearly 38 percent were related to cancers. This was more than both vascular events and infections combined, making cancer a top player in misdiagnosis-related harms.¹

Interestingly, although cancer-related misdiagnosis made up the majority of these cases, the actual incidence of cancer is much lower than that of infection and vascular events. This means that though many more people have vascular events and infections, these are not the most common conditions related to misdiagnosis. This highlights the importance of cancer in relation to misdiagnosis and its related harms.¹

Specifically, the researchers identified 5 conditions within each Big Three category that made up about half of all misdiagnosis-related malpractice cases. This means that 15 conditions (5 from each category) represented 50 percent of all diagnostic error cases.¹

For vascular events, these included heart attack and stroke. Infections included pneumonia and sepsis, among others. The top 5 cancers that were related to diagnostic error were:¹

• Lung cancer
• Colorectal cancer
• Breast cancer
• Melanoma
• Prostate cancer

How is cancer misdiagnosed?

Infection and vascular-related diagnostic errors were most often found in the hospital or emergency room setting. But cancer-related misdiagnosis events were most commonly reported in the outpatient or clinic setting. The researchers thought issues with continuous care during the sometimes slow and sneaky onset of some cancers may be the reason they are often misdiagnosed in the clinic.¹

The long-term and potentially discontinuous care in clinics may also lead to poor follow-up when it comes to diagnostic testing. Important information may fall through the cracks.¹

Future research on the Big Three

The researchers and the SIDM are hoping to use this information to inspire change and initiatives to help reduce misdiagnosis and misdiagnosis-related harms. The team of researchers are working on follow-up studies to look at the true proportion of Big Three-related diagnostic errors in the population. They also want to find out more about the impact of these misdiagnoses.¹