Abstract
Objective
This study will evaluate the effect of a Computerized Physician Order Entry system with basic Clinical Decision Support (CPOE/CDSS) on the incidence of medication errors (MEs) and preventable adverse drug events (pADEs).
Design
Interrupted time-series design.
Measurements
The primary outcome measurements are comprised of the percentage of medication orders with one or more MEs and the percentage of patients with one or more pADEs.
Results
Pre-implementation, the mean percentage of medication orders containing at least one ME was 55%, whereas this became 17% post-implementation. The introduction of CPOE/CDSS has led to a significant immediate absolute reduction of 40.3% (95%CI:-45.13%;-35.48%) in medication orders with one or more errors. Pre-implementation, the mean percentage of admitted patients experiencing at least one pADE was 15.5%, as opposed to 7.3% post-implementation. However, this decrease could not be attributed to the introduction of CPOE/CDSS: taking into consideration the interrupted time-series design, the immediate change was not significant (-0.42%, 95% CI:-15.52%; 14.68%) because of the observed underlying negative trend during the pre-CPOE period of -4.04% [95% CI: -7.70%; -0.38%] per month.
Conclusion
This study has shown that CPOE/CDSS reduces the incidence of medication errors. However, a direct effect on actual patient harm (pADEs) could not be demonstrated.
van Doormaal JE, van den Bemt PM, Zaal RJ, Egberts AC, Lenderink BW, Kosterink JG, et al. The influence of computerized prescribing on medication errors and preventable adverse drug events: an interrupted time series study. J Am Med Inform Assoc. 2009 Dec;16(6):816-25.

