Effect of background case characteristics on decisions in the delivery room.

BACKGROUND: The authors investigated whether obstetricians make different decisions about a medical test case depending on the characteristics of background cases that preceded the test case. METHODS: Five hypothetical cases were sent to 1247 obstetricians. The outcome of interest was the proportion of physicians who elect to perform a cesarean on a borderline test case, presented with 4 background cases. Participants were randomly assigned to 1 of 3 conditions: 1) pathological background, in which the test case was preceded by abnormal cases, typically requiring cesarean; 2) physiological background, where the test case was preceded by relatively uncomplicated cases, often suggesting a less invasive treatment; and 3) control, where the test case appeared first. RESULTS: A significantly higher proportion of respondents chose a cesarean when the test case was preceded by physiological cases (75.4%) than when it was preceded by pathological cases (52.2%). This tendency was observed among those actively and not actively involved in obstetrics and in physicians with different levels of training. CONCLUSIONS: A patient's chances of undergoing cesarean section can be influenced by the immediately prior experience of the physician. This study with hypothetical vignettes found that background cases can influence physicians' decisions. The test case was apparently perceived as more grave when it followed uncomplicated cases as compared to when it was preceded by abnormal cases. Such inconsistencies in decision making are unlikely to be fully resolved by expertise, as suggested by the lack of differences between physicians with different training levels. An understanding of such effects may contribute to more informed consideration of unappreciated influences in making decisions.