Medication Dispensing Errors and Potential Adverse Drug Events before and after Implementing Bar Code Technology in the Pharmacy

BACKGROUND: Many dispensing errors made in hospital pharmacies can harm patients. Some hospitals are investing in bar code technology to reduce these errors, but data about its efficacy are limited. OBJECTIVE: To evaluate whether implementation of bar code technology reduced dispensing errors and potential adverse drug events (ADEs). DESIGN: Before-and-after study using direct observations. SETTING: Hospital pharmacy at a 735-bed tertiary care academic medical center. INTERVENTION: A bar code-assisted dispensing system was implemented in 3 configurations. In 2 configurations, all doses were scanned once during the dispensing process. In the third configuration, only 1 dose was scanned if several doses of the same medication were being dispensed. MEASUREMENTS: Target dispensing errors, defined as dispensing errors that bar code technology was designed to address, and target potential ADEs, defined as target dispensing errors that can harm patients. RESULTS: In the pre- and post-bar code implementation periods, the authors observed 115,164 and 253,984 dispensed medication doses, respectively. Overall, the rates of target potential ADEs and all potential ADEs decreased by 74% and 63%, respectively. Of the 3 configurations of bar code technology studied, the 2 configurations that required staff to scan all doses had a 93% to 96% relative reduction in the incidence of target dispensing errors (P < 0.001) and 86% to 97% relative reduction in the incidence of potential ADEs (P < 0.001). However, the configuration that did not require scanning of every dose had only a 60% relative reduction in the incidence of target dispensing errors (P < 0.001) and an increased (by 2.4-fold) incidence of target potential ADEs (P = 0.014). There were several potentially life-threatening ADEs involving intravenous dopamine and intravenous heparin in that configuration. LIMITATIONS: The authors used surrogate outcomes; did not mask assessors to the purpose of study; and excluded the controlled substance fill process (a process with low error rates at baseline) from the study, which may bias the combined decrease in error rates toward a larger magnitude. CONCLUSIONS: The overall rates of dispensing errors and potential ADEs substantially decreased after implementing bar code technology. However, the technology should be configured to scan every dose during the dispensing process.