The effect of immediate access to a computerized medical record on physician test ordering: a controlled clinical trial in the emergency room.

We performed a randomized clinical trial of the effect of immediately printed summaries of a computerized medical record on physician test ordering rates in an Emergency Room setting. The computerized medical record contained medication history, the results of most diagnostic studies, an outpatient problem list, and inpatient and emergency room diagnoses. Physicians were presented with a printed summary of the patient's computerized record for study but not for control encounters. All other patient information was equally available to both kinds of encounters. All results were provided for one period of the study, designated T1. Due to a program error, summaries were printed without recent data during a period of the study, designated T2. Two-thirds of the visits were cared for by internists, one-third by surgeons. During T1, internists ordered an average of 3.2 tests, costing $34.91 for control visits, and 2.7 tests, costing $29.94 for study control visits (p less than .026). Surgeons also ordered fewer tests during study visits as compared to controls (1.32 vs 1.54) but the differences were not statistically significant. There was no significant effect on either medical or surgical test ordering during time period T2.