Surrogate decision makers for incapacitated, critically ill patients systematically interpreted prognostic information as being more optimistic than it actually was, in a study published in the March 6 issue of the Annals of Internal Medicine.
These surrogate decision makers accurately interpreted prognostic information that was positive, but not prognostic information expressing a high risk of death. Instead, they showed "a systematic bias," consistently interpreting "grim" prognostic statements in an overly optimistic way, said Dr. Lucas S. Zier of the University of California, San Francisco, and his associates.
"These findings challenge the prevailing assumption in the medical literature that discordance between physicians and surrogates about prognosis is due largely to unclear disclosure by physicians or simple misunderstandings by surrogates," the investigators noted.
The results also indicate that any efforts to improve this aspect of decision making must address not just the clarity of prognostic statements but also the "emotional and psychological factors that affect how individuals process such information," they added.
"Clinicians who communicate with surrogate decision makers in the care of incapacitated patients should be aware of the diverse causes for discordance about prognosis."
Dr. Zier and his colleagues examined how surrogate decision makers interpret physicians’ statements about their loved ones’ prognosis by administering a questionnaire to 80 such surrogates who were accompanying an incapacitated patient at medical-surgical ICUs in a Veterans Affairs hospital, a tertiary academic hospital, and a public county hospital.
The questionnaire presented 16 possible prognostic statements in the language used by physicians and made it clear that these represented hypothetical clinical situations unrelated to their loved one’s cases. Study subjects were asked what exactly each prognostic statement meant to them, and used a numerical scale to demarcate the patient’s chance of survival corresponding to each prognostic statement.
Examples of general and somewhat equivocal prognostic statements included "It is very likely that he will survive," "It is very unlikely that he will die," "I am concerned that he will not survive," "It is possible he will not survive," and "He probably will not survive." Unequivocal prognostic statements were "He will definitely survive" and "He will definitely not survive."
There also were three unequivocal numerical prognostic statements: "He has a 90% chance of surviving," "He has a 50% chance of surviving," and "He has a 5% chance of surviving."
Only twelve surrogate decision makers (15% of the entire group) interpreted the three numerical prognostic statements accurately. Almost as many – 13% –interpreted all three numerical prognostic statements more optimistically than they actually were.
Most surrogates interpreted the statement of a low risk of death ("90% chance of surviving") accurately, but severely misinterpreted the statements of a median or high risk of death. Forty percent thought that "a 50% chance of surviving" meant that the patient was likely to survive, and 65% thought that "a 5% chance of surviving" meant that the patient was likely to survive.
No surrogates interpreted any of the numerical prognostic statements more pessimistically than they actually were.
Some experts have advocated using straightforward, numerical language when communicating medical risk to surrogate decision makers, but these findings clearly show that numbers are not straightforward to everyone and are frequently misinterpreted, Dr. Zier and his associates said (Ann. Intern. Med. 2012;156:360-6).
In the second phase of this study, 15 subjects whose interpretations of prognostic statements had been particularly off-base were interviewed about why there was such a discrepancy between what the physician said and what the subject thought was meant.
Seven of the 15 said they were unaware that almost all their interpretations were overly optimistic. These subjects were surprised when it was pointed out to them and couldn’t offer of an explanation.
The other eight surrogate decision makers gave four reasons for their "optimism bias."
Some said they intentionally expressed optimism as long as there was any hope whatsoever. This may represent a coping strategy to help surrogates deal with having a critically ill loved one. Or it may represent "magical thinking" in which people believe their positive thoughts and expectations can actually improve the patient’s outcome, the researchers said.
Other surrogate decision makers said they believed their loved one was exceptional and wouldn’t die because of an unusual will to live and ability to survive. This "may represent a cognitive bias known as illusory superiority, unrealistic optimism, or the ‘Lake Wobegon effect,’ a cognitive bias that leads people to overestimate, in relation to others, their likelihood of experiencing positive outcomes and avoiding negative outcomes," the investigators said.
Some study subjects said they intentionally ignored numerical probabilities and precise language, preferring to judge "the overall feeling that the doctor is conveying."