A recent study by the Mayo Clinic found that more than 20 percent of patients who sought a second opinion had previously been misdiagnosed by their primary care physician. During the two-year study, researchers examined the records of 286 patients who had seen primary care physicians, physician assistants and nurse practitioners in 2009 and 2010. Nearly two-thirds of the patients were under the age of 64, and the majority of patients were female. After receiving an initial diagnosis, each patient sought a second opinion from the Mayo Clinic’s General Internal Medicine Division. Of the 286 patients, only 36 patients (12 percent) had received confirmation that the original diagnosis was complete and correct. In 63 cases (21 percent), the diagnosis was completely changed meaning the patient had been misdiagnosed by their primary care physician. In the remaining 188 cases (66 percent), patients received a refined or redefined diagnosis. Researchers did not find any significant differences between provider types.
The Mayo Clinic study is consistent with previous studies which concluded that misdiagnosis by physicians is a relatively common, yet understudied and underreported, occurrence in the health care industry. In 2013, the National Center for Policy Analysis reported that an estimated 10 to 20 percent of cases are misdiagnosed, a number which exceeds drug errors and surgical errors involving the wrong patient or wrong body part, both of which receive considerably more attention. In 2015, the National Academy of Medicine reported that most people will receive an incorrect or late diagnosis at least once in their lives, sometimes with serious and even deadly consequences. The report cited one estimate that such errors affect at least 12 million adults who seek outpatient care annually.