At least one in 20 adults is misdiagnosed in outpatient clinics in the U.S. every year, amounting to 12 million people nationwide, with half the cases potentially harmful and posing a “substantial patient safety risk,” a study found.
To date, patient safety improvements have largely focused on hospital stays and issues such as infections, falls, and medication errors, say the authors. But most diagnoses are made in outpatient clinics, where patients are looked after by several different health care teams and few safety concerns are ever reported.
To gauge the numbers of diagnostic errors made in U.S. outpatient clinics every year, the authors combined data from 3 previous studies. The first used an algorithm to detect unexplained return visits or hospitalizations within 14 days of an initial visit in a primary care setting. The second used an algorithm to detect a lack of follow-up of abnormal clinical findings for colorectal cancer. A third study examined consecutive cases of lung cancer in 2 institutions. In all 3 studies, diagnostic errors were confirmed through chart review.
The records were reviewed in detail to see there had been a diagnostic error, defined as missed opportunities to make a timely or correct diagnosis based on available evidence. The proportion of errors found was then applied to the larger population of all outpatient visits and then to the U.S. adult population as a whole to estimate the annual frequency of misdiagnoses.
The study appeared online in BMJ Quality & Safety.
The authors calculated the numbers of new cases of misdiagnoses at 5.08%, about half which could potentially be harmful, based on previous studies by the researchers.
If these figures are applied to the U.S. population as a whole, this works out at around 12 million adults each year. And, the authors wrote, the rate of misdiagnoses could be an underestimate, based on conditions not considered by the study, such as other types of cancer and other chronic conditions.