PURPOSE: To determine the impact of giving physicians computerized reminders about apparently redundant clinical laboratory tests.

SUBJECTS AND METHODS: We performed a prospective randomized controlled trial that included all inpatients at a large teaching hospital during a 15-week period. The intervention consisted of computerized reminders at the time a test was ordered that appeared to be redundant. Main outcome measures were the proportions of clinical laboratory orders that were canceled and the proportion of the tests that were actually performed.

RESULTS: During the study period, there were 939 apparently redundant laboratory tests among the 77,609 study tests that were ordered among the intervention (n = 5,700 patients) and control (n = 5,886 patients) groups. In the intervention group, 69% (300 of 437) of tests were canceled in response to reminders. Of 137 overrides, 41% appeared to be justified based on chart review. In the control group, 51% of ordered redundant tests were performed, whereas in the intervention group only 27% of ordered redundant tests were performed (P <0.001). However, the estimated annual savings in laboratory charges was only $35,000. This occurred because only 44% of redundant tests performed had computer orders, because only half the computer orders were screened for redundancy, and because almost one-third of the reminders were overridden.

CONCLUSIONS: Reminders about orders for apparently redundant laboratory tests were effective when delivered. However, the overall effect was limited because many tests were performed without corresponding computer orders, and many orders were not screened for redundancy.