According to a new study, at least one in every 20 adult outpatients are misdiagnosed by their doctor each year. These misdiagnoses pose a “substantial patient safety risk.”

Fifty percent of these misdiagnoses (amounting to 12 million people nationwide) could be potentially harmful, posit the authors, who contend that their results should encourage improved efforts to monitor and decrease the numbers of misdiagnoses.

Hardeep Singh, lead author of the paper, which appeared in the journal BMJ Quality & Safety, told the Boston Globe, “The question is, can we eliminate human error, and the answer is no.” He continued, “We have just now begun to understand what [these errors] are and what we can do.”

Singh explained that patients and their care teams, along with the healthcare system, need to work together to help reduce these mistakes.

Singh, a patient safety researcher at the Veterans Affairs Center for Innovations, and Baylor College of Medicine, both of which are in Houston, also noted that doctors need to tread carefully between missing diagnoses and performing such a high number of tests that they ultimately treat patients for something that is best left alone.

Gordon Schiff, internist and associate director of the Center for Patient Safety Research and Practice at Brigham and Women’s Hospital and an associate professor at Harvard Medical School, explained to the Boston Globe, “The problem of diagnostic errors in general has not been front-and-center in the patient safety movement until recently. And the problem of outpatient safety and diagnostic safety in the outpatient setting has been even more overlooked and harder to get our hands around.”

Schiff concluded, “This [new study] is a very good first pass at trying to really in a more rigorous way establish the incidence of diagnostic errors.”