New research suggests that about one in 20 patients are misdiagnosed.

About half of these cases pose a "substantial patient safety risk" and could be "potentially harmful," a BMJ-British Medical Journal news release reported.

The study calls for efforts to improve screening processes and work to cut down on the number of misdiagnosis.

In the past, improvement efforts in patient care have mainly focused on" infections, falls, and medication errors," the news release reported. These efforts have also largely focused on hospital stays, but most diagnosis are made in outpatient clinics.

There are no "reliable estimates" as to how many people are really misdiagnosed every year, making it more difficult to work out how to combat them.

In order to get a better idea of the misdiagnosis situation the researchers looked at several published studies than encompassed thousands of medical records, all from outpatient clinics.

This study could help lead the way for other assessments to be made in fields such as "malpractice data, autopsy reports, or specialized fields of medicine," the news release reported.

The researchers thoroughly reviewed each case to determine if any diagnostic errors had been made. The team then applied the proportion of errors found in the reports with a larger population of all outpatient visits and to the entire adult population in the U.S.

Based on this study the researchers estimated the number of misdiagnosis were at about 5.08 percent, which translates to about one in every 20 cases. About half of these misdiagnosis are believed to be potentially harmful.

When the findings were applied to the entire adult U.S. population it looked like about12 million adults each year experienced misdiagnoses.

"Healthcare organizations, patient advocates, policymakers, and researchers should use the findings to push for further strategies to improve patient safety in this area," the news release reported.