- Kenny Lin, MD, MPH
Due to our broad scope of practice, family physicians are likely the most vulnerable of all physicians (with the possible exception of emergency medicine physicians) to diagnostic errors. Patients of all ages and different co-morbidities come in with undifferentiated complaints that could be attributed to multiple organ systems. In an editorial in the September 15th issue of AFP, Drs. John Ely and Mark Graber reviewed underlying reasons for incorrect diagnoses:
Most diagnostic errors are caused by the physician's cognitive biases and failed heuristics (mental shortcuts), such as anchoring bias (overly relying on the initial information received or initial diagnosis considered), context errors, or premature closure of the diagnostic process. More than 40 of these biases have been described, but most lead to a single pathway in which the physician fails to generate an adequate differential diagnosis or to even consider the correct diagnosis as a possibility. The single most common reason for a diagnostic error is simply, “I just didn't think of it."
In a previous Curbside Consultation, Dr. Caroline Wellbery explored some of these cognitive biases in greater detail. For example, availability bias "refers to the ease with which a particular answer comes to mind," and can lead physicians toward making diagnoses based on other recent patients with similar presenting symptoms. Premature closure may occur when a framing/anchoring bias causes a physician to view the patient through a familiar lens and dismiss evidence that is not consistent with that frame. Similarly, confirmation bias may lead physicians to overemphasize test findings that support their preliminary diagnoses. Dr. Allan Detsky brought some of these dry concepts to life in a recent narrative in JAMA where he compared difficult diagnoses to the plastic snakes that he used to scare away ducks from the dock at his family's vacation home:
When faced with a difficult and ongoing diagnostic dilemma, refocus on the key assumptions that have driven the strategy to search for the "snakes." Start by dividing the findings into those that are based on facts and those that are based on inferences derived from those facts. Design an experiment to see if those inferences are indeed true, like holding the snakes under the water to see what they will look like on the bottom of the lake.
In their AFP editorial, Drs. Ely and Graber suggested three approaches to reduce diagnostic errors in primary care: 1) Involve the patient as a partner in the diagnostic process; 2) Get second opinions from colleagues or consultants who have not been previously involved in the patient's care; 3) Use a diagnostic checklist to make sure that all appropriate differential diagnoses have been considered. On a health system level, the National Academies of Medicine published a report on "Improving Diagnosis in Health Care" last year, and the Society to Improve Diagnosis in Medicine is leading a coalition of professional organizations, including the American Academy of Family Physicians, to devise and implement strategies to prevent diagnostic errors across all specialties and healthcare settings.