Objective To determine the effect that the computer interpretation (CI) of EKGs has on the accuracy of resident (non-cardiologist) physicians reading EKGs.

Design Randomized controlled trial conducted in a laboratory setting from February-June 2001, using a 2 period crossover design with matched pairs of subjects randomly assigned to sequencing groups.

Measurements Subjects' interpretive accuracy of discrete, cardiologist-determined EKG findings, as judged by a board-certified internist.

Results Without the CI, subjects interpreted 48.9% (95% confidence interval 45.0% to 52.8%) of the findings correctly. With the CI, subjects interpreted 55.4% (51.9% to 58.9%) correctly (p < 0.0001). When the CIs that agreed with the gold standard (Correct CIs) were not included, 53.1% (47.7% to 58.5%) of the findings were interpreted correctly. When the correct CI were included accuracy increased to 68.1% (63.2% to 72.7%; p < 0.0001). When computer advice that did not agree with the gold standard (Incorrect CI) was not provided to the subjects, 56.7% (48.5% to 64.5%) of findings were interpreted correctly. Accuracy dropped to 48.3% (40.4% to 56.4%) when the incorrect computer advice was provided (p = 0.131). Subjects erroneously agreed with the incorrect CI more often when it was presented with the EKG 67.7% (57.2% to 76.7%) than when it was not 34.6% (23.8% to 47.3%; p < 0.0001).

Conclusion Computer decision support systems can generally improve the interpretive accuracy of internal medicine residents in reading EKGs. However, subjects were significantly influenced by incorrect advice which tempers the overall usefulness of computer generated advice in this and perhaps other areas.