In the popular mind, severing the wrong limb or leaving a surgical instrument in the patient are probably the two most common stereotypes of medical malpractice. Two recent studies by insurance companies that insure physicians against malpractice claims provide information that rebuts these stereotypes. In fact, both studies found that mistaken diagnosis and not some form of erroneous procedure is the leading reason for medical malpractice claims.

Coverys, a malpractice insurer located in Boston, reviewed 1,800 closed malpractice claims between 2013 and 2017. Of those claims, 46 percent arose from diagnosis issues. Those claims accounted for 68 percent of paid indemnity costs for the 1,800 cases in the sample. The Doctors Company, a malpractice insurer located in California, found in a review of 1,215 pediatric malpractice claims that 38 percent of the cases resulted from mistaken diagnoses. The Doctors Company study also concluded that diagnostic errors were largely the result of inadequate medical assessment by the health care team. Older studies have reached similar conclusions, including a study by the National Academy of Medicine that found that diagnostic error was the third leading cause of death for hospitalized patients.

The Coverys’ study concluded that the most common allegation against primary care providers involved an inadequate assessment of the patient and the patient’s family history. Errors also included the doctor’s failure to obtain a complete family medical history. Mistakes in ordering diagnostic tests was the second-most common mistake made by physicians. The Doctors Company study said that many of the negligent physicians failed to recognize the clinical picture from available evidence, including patient histories, reported symptoms, physical exams and test results.

The Doctors Company study also provided information on the amount paid for malpractice claims. Of the 1,215 claims reviewed, 446 (37 percent) resulted in payments to plaintiffs. The average indemnity payment was $630,456, and the average expense per claim was $157,592.