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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 judgment."

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, Mass.

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.

11/16/98