Physicians misdiagnose comatic states 40 percent of the time, study finds

Distinguishing between different types of coma patients has never been easy. In fact, in 1996, the Royal Hospital for Neurodisability in London found that 40 percent of inpatients who had been diagnosed as being in a vegetative state, were not. Several years ago, two new tools were developed to help physicians better distinguish comatose states. These included a new diagnostic category called the "minimally conscious" state, a description given to patients who are slightly better off than those in a vegetative state, as they show fluctuating signs of awareness. For example, they may at certain times, but not at others, pass the eyeblink test. A second tool, which is called the JFK Coma Recovery Scale, is widely regarded as enabling physicians to definitively distinguish patients in a vegetative state from those with minimal consciousness, as well as identify those who had previously been in a minimally conscious state, but who had emerged from it.

So have these tools made a difference? In a study just published in BioMed Central Neurology, a team of researchers including Caroline Schnakers and Steven Laureys from the University of Liège's coma science group suggest that physicians still may not be able to clearly tell the difference between coma patients. The study also found that physicians may prefer to use their intuition, rather than the latest diagnostic techniques, to determine the patient's exact comatose state. The result may be that patients are terminated even after showing minimal signs of awareness.

 Their findings were based on comparing the diagnoses of 103 patients given by the medical staff looking after those patients with the diagnoses determined by the coma recovery scale. Of those patients, 44 had been diagnosed by the staff as vegetative, whereas the coma scale suggested that 18 of those 44 were in a minimally conscious state -- a 40 percent error rate. It also found that 4 of the 40 patients diagnosed as in a minimally conscious state had actually emerged from that state.

Dr. Laureys' measured conclusion is that "neurologists do not like their skills to be replaced or upstaged by a scale." With the minimally conscious state being a relatively new diagnosis, he says, "it may be that some doctors are unfamiliar with its criteria, but that is all the more reason for deferring to the coma recovery scale. The trouble with a diagnosis based on conviction, rather than on measurement, is that it is vulnerable to external influence. Insurance companies, for example, prefer a diagnosis of vegetative to one of minimally conscious, because no expensive rehabilitation is required for those in a vegetative state."

 News Release: Diagnosing comas: Unlucky for some  www.economist.com  July 23, 2009