CLINICAL-DIAGNOSIS AND THE ORDER INFORMATION

Background. Information order can influence judgment. However, it rema ins unclear whether the order of clinical data affects physicians' int erpretations of these data when they are engaged in familiar diagnosti c tasks. Methods. Of 400 randomly selected family physicians who were given a questionnaire involving a brief written scenario about a young woman with acute dysuria, 315 (79%) returned usable responses. The ph ysicians had been randomized into two groups, and both groups had rece ived the same clinical information but in different orders. After lear ning the patient's chief complaint, physicians received either the pat ient's history and physical examination results followed by the labora tory data (the H&P-first group) or the laboratory data followed by the history and physical examination results (the H&P-last group). The re sults of the history and physical examination were supportive of the d iagnosis of UTI, while the laboratory data were not. All physicians ju dged the probability of a urinary tract infection (UTI) after each pie ce of information. Results. The two groups had similar mean estimates of the probability of a UTI after learning the chief complaint (67.4% vs 67.8%, p = 0.85). At the end of the scenario, the H&P-first group j udged UTI to be less likely than did the H&P-last group (50.9% vs 59.1 %, p = 0.03) despite having identical information. Comparison of the m ean likelihood ratios attributed to the clinical information showed th at the H&P-first group gave less weight to the history and physical th an did the H&P-last group (p = 0.04). Conclusions. The order in which clinical information was presented influenced physicians' estimates of the probability of disease. The clinical history and physical examina tion were given more weight by physicians who received this informatio n last.