Case analysis: representation bias and specialization

Grand Central Station, New York, USA

A 77-years-old woman had a diagnosis of Gastrointestinal Sarcoma Tumor (GIST) and she was taking imatinib for a period of two years. One month before she was admitted to the hospital ,she started with dyspnea when climbing stairs. An x-ray taken in the Emergency Department showed a left  pleural effussion that her doctor associated with imatinib.



CLINICAL EVOLUTION: Her doctor decided not to ask for more tests because the diagnosis was clear for her, imatinib toxicity.  The patient was treated with prednisone, analgesic and oxygen without clinical improvement. After three days a CAT scan was ordered and a new finding was detected in the left lobe suggesting the possibility of an infection.



TYPE OF ERROR: Wrong Diagnosis


. Cognitive: Representation Bias 

The combination of pleural effusion and imatinib represented for the doctor a pattern in her mind associated with an uncommon toxicity but very well known by the oncologist. But thinking in terms of prevalence usually a respiratory infection is more prevalent in the general population.

MEASURES TO IMPROVE: Always try to list a broad differential, including the prevalent problems.