Groopman catalogues the many species of clinical errors, a whole taxonomy of misperceptions and wrong conclusions illustrated with real examples offered as representative types. All are fascinating, a few are chilling.
Into the latter category falls the case of a woman who for 15 years suffered from chronic diarrhea, vomiting and eventually anemia, osteoporosis and severe weight loss. Doctors said she had anorexia, bulimia and irritable bowel syndrome -- a proliferation of diagnoses that should have been a hint they were wrong. After initially resisting, she had come to accept this explanation of her problem, dutifully taking antidepressants and forcing down 3,000 calories of largely indigestible food each day. By the time she consulted one of Groopman's colleagues at Beth Israel Deaconness Hospital in Boston, she weighed 82 pounds. He diagnosed celiac disease, an allergy to the protein gluten found in many grains. The disease denudes the inner surface of the small intestine, reducing its ability to absorb nutrients; it explained all her symptoms.
The woman "was fitted into the single frame of bulimia and anorexia nervosa from the age of twenty," writes Groopman. "It was easily understandable that each of her doctors received her case within that one frame. All the data fit neatly within its borders. There was no apparent reason to redraw her clinical portrait, to look at it from another angle.
Many of the mistakes Groopman describes are variants of this one. They come from the physician's inability to keep his or her mind open, a reluctance to abandon initial impressions or received wisdom, and a willingness to ignore (often unconsciously) contradictory evidence. At the same time, the facts of biology rightly steer physicians away from endlessly pursuing improbable diagnoses -- a truth captured in such medical-school aphorisms as: "When you hear hoofbeats, don't immediately think of zebras" and "Don't forget that common things are still common."
"It is a matter," Groopman writes, "of juggling seemingly contradictory bits of data simultaneously in one's mind and then seeking other information to make a decision, one way or another. This juggling . . . marks the expert physician -- at the bedside or in a darkened radiology suite."
This need for self-awareness during the act of thinking and working extends to the physician's emotional state and personal beliefs. How a doctor feels about a patient can have a major effect on the care provided to people who are obese, poor, stupid, mentally ill, addicted, foreign, criminal, deviant or ill-smelling -- as well as to those who are rich, powerful, famous, personally familiar or smarter than the doctor.