Geriatrics is a field of sleuthing. To solve medical enigmas, doctors must become detectives, teasing out the effects of overlapping causes that include chronic conditions, acute injuries, social factors and the normal process of aging. It is a challenge that tests the patience of many doctors; the number of certified geriatricians in the United States, now just over 7,000, has been decreasing since 2017.

By masquerading as a diagnosis, the term “failure to thrive” cuts that sleuthing process short, shutting down inquiry before doctors can determine the real cause, said Dr. Clara Tsui, a geriatrician at St. Paul’s Hospital in Vancouver, British Columbia. Last month, she saw the label in the medical notes of an 82-year-old man with Alzheimer’s, who had fallen and hit his head. Even though a brain scan showed internal bleeding, the man had been diagnosed only with “failure to thrive” — which, Dr. Tsui noted, “is not a diagnosis at all.”

Dr. Martha Spencer, a geriatrician and colleague of Dr. Tsui at St. Paul’s, called the phrase vague, demeaning and ageist. “It baffles me as to why it’s lingered so long,” she said.

In 2020, Dr. Spencer and Dr. Tsui led a study that found that older patients who were given the label “failure to thrive” waited significantly longer to be admitted to a hospital. Once admitted, these patients experienced longer hospital stays, which are known to increase the risk of infection and other complications. By the time these patients were released, most of them — 88 percent — had received specific diagnoses, such as kidney failure or severe dehydration.

In other words, the authors concluded, the “failure” label tended to mask treatable illnesses, while burdening the patient with unnecessary delays in their care. A diagnosis of “failure” could become a self-fulfilling prophecy, leading doctors to assume that they were just another older patient on the inevitable path to decline. (Similarly, researchers have found that “acopia,” a bit of medicalese that literally means “not coping” and is still sometimes used in the U.K. and Australia, often leads doctors to overlook acute illnesses.)