Don't Blame Hospitals for All Diagnostic Errors

"This is the first step in trying to establish a measure of this problem and try to understand it. And we know, it opens up a lot of new areas to figure out what's next," Singh says.

By far, the largest share of factors contributing to the errors involved elements within the patient-practitioner encounter. For example, that the physician had a problem ordering diagnostic tests for further workup contributed to the cause of 109 of the errors.

Failure to take an accurate medical history contributed to the cause of 107 of the errors. And problems with the performance of the physician's physical examination of the patient contributed to 90. Each of the 190 errors they discovered had multiple causes.

"We found that often, the most important thing was taking the history, doing the physical exam and ordering the right tests based on your assessment of the patient," Singh says.

The researchers discovered that the patient's own actions and behavior, or that of his or her family members, in the practice setting, seldom led to a contributing cause of the error. For example, failure of the patient to provide an accurate medical history contributed to only 14 of the errors.

Other less frequent contributors included physicians' inadequate test result tracking systems, the physician setting too long of a period for a follow-up visit, or errors in which the clinician erroneously considered the condition as not serious.