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UI study shows information order affects physician's diagnosis
IOWA CITY, Iowa -- The order in which a physician receives information
about a patient's problem may affect the doctor's ultimate diagnosis --
even for a fairly common condition, according to a University of Iowa study.
Researchers compared the conclusion that two groups of family physicians
made about a patient's complaint of painful urination. One group first
looked over the patient's medical history and the results from a physical
examination, and then viewed the information from a urinalysis. The second
group received the lab results first. The researchers presented identical
information to both groups.
The findings, published in the current issue of Medical Decision Making,
showed those who first analyzed the history and physical exam results were
less likely to diagnose the problem as a urinary tract infection than those
who viewed that information last -- 50.9 percent to 59.1 percent.
"Doctors, just like others who are involved in analyzing information,
are sensitive to the order in which they review it," said Dr. George
Bergus, UI associate professor of family medicine and the study's lead
investigator. "Order influence is something common in professional
The researchers received back 315 usable surveys from its mailing to
400 randomly chosen Iowa family physicians. The questionnaire started with
a brief description of the patient, a 28-year-old woman, and the chief
complaint, discomfort of urination. After the introductory description,
the physicians rated whether they thought the patient had a urinary tract
infection. The results were almost identical -- 67.4 percent for those
who would receive the history and exam results first and 67.8 percent for
those who would receive the lab results first.
The physicians then received additional clinical information in one
of two ways: medical history and physical examination first or lab results
first. The history and physical exam suggested a urinary tract infection,
while the urinalysis was less conclusive. In their second estimate, after
receiving the first set of data, the group's estimates changed, 77.8 percent
for those who had the history and physical exam information and 44.0 percent
for those who had viewed the urinalysis data.
On the third and final rating, after the physicians had all the information,
those who saw the history and physical exam data first gave a 50.9 percent
probability of a urinary tract infection, while the other group put the
likelihood at 59.1 percent.
Other studies, involving other investigators, have shown similar information
order effects in air defense personnel determining whether targets were
hostile, army analysts interpreting intelligence reports, employment interviewers
evaluating applications and auditors appraising financial reports.
Patients are not immune, either. Results from a separate study, which
Bergus and his colleagues conducted over the past two summers, showed that
if patients first received information about the risk of a low invasive
procedure and only then information about the benefit, they were more likely
to have the procedure done. Bergus presented those findings Oct. 25 at
the 1998 Annual Meeting of the Society of Medical Decision Making in Cambridge,
Bergus said no one has yet developed methods to guard against influences
of information ordering.
"In our latest example we wanted to look at a common scenario that
primary care physicians deal with frequently to see whether the effect
holds true," said Bergus, who has conducted prior studies in the area
dealing with more complex problems that required specialized knowledge.
The urination complaint, called acute dysuria, is responsible for nearly
seven million visits to physicians' offices each year and for 2 to 3 percent
of all visits to primary care physicians. Although the researchers did
not specifically ask about the doctor's knowledge of urinary tract infections,
a previous study of family physicians indicated that 99 percent felt comfortable
dealing with the infection and, on average, each physician treated seven
cases per week.
Some might contend that the order effect is due solely to the untraditional
approach of reviewing the history and physical exam information after the
lab data. That might be the case with other conditions but less likely
with a urinary compliant, Bergus said. In many primary care settings, physicians
see the results of a urinalysis, which the nursing staff conducts when
the patient arrives, before taking down the medical history or performing
a physical exam.